# Reference


- [Notions](#notions)
  - [Mock function](#mock_function)
  - [Mock object](#mock_object)
  - [Expectation](#expectation)
  - [Matcher](#matcher)
    - [_](#wildcard)
    - [**`ANY(`** *type* **`)`**](#ANY)
    - [**`MEMBER_IS(`** *member*, *matcher* **`)`**](#MEMBER_IS)
    - [**`all_of(`** *values* **`)`**](#all_of)
    - [**`any_of(`** *values* **`)`**](#any_of)
    - [**`eq(`** *value* **`)`**](#eq)
    - [**`ne(`** *value* **`)`**](#ne)
    - [**`gt(`** *value* **`)`**](#gt)
    - [**`ge(`** *value* **`)`**](#ge)
    - [**`lt(`** *value* **`)`**](#lt)
    - [**`le(`** *value* **`)`**](#le)
    - [**`none_of(`** *values* **`)`**](#none_of)
    - [**`re(`** *string* **`)`**](#re)
    - [**`range_includes(`** *values **`)`**](#range_includes)
    - [**`range_is(`** *values* **`)`**](#range_is)
    - [**`range_all_of(`** *matcher* **`)`**](#range_all_of)
    - [**`range_any_of(`** *matcher* **`)`**](#range_any_of)
    - [**`range_none_of(`** *matcher* **`)`**](#range_none_of)
    - [**`range_is_permutation(`** *values* **`)`**](#range_is_permutation)
    - [**`range_starts_with(`** *values* **`)`**](#range_starts_with)
    - [**`range_ends_with(`** *values* **`)`**](#range_ends_with)
    - [**`*`** *matcher*](#deref_matcher)
    - [**`!`** *matcher*](#not_matcher)
- [Macros](#macros) (alphabetical order)
  - [**`ALLOW_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#ALLOW_CALL)
  - [**`ANY(`** *type* **`)`**](#ANY_MACRO)
  - [**`AT_LEAST(`** *number* **`)`**](#AT_LEAST)
  - [**`AT_MOST(`** *number* **`)`**](#AT_MOST)
  - [**`CO_RETURN(`** *expr **`)**](#CO_RETURN)
  - [**`CO_THROW(`** *expr **`)**](#CO_THROW)
  - [**`CO_YIELD(`** *expr **`)**](#CO_YIELD)
  - [**`FORBID_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#FORBID_CALL)
  - [**`IMPLEMENT_CONST_MOCKn(`** *func_name* **`)`**`](#IMPLEMENT_CONST_MOCKn)
  - [**`IMPLEMENT_MOCKn(`** *func_name* **`)`**`](#IMPLEMENT_MOCKn)
  - [**`IMPLEMENT_STDMETHOD_MOCKn(`** *func_name* **`)`**`](#IMPLEMENT_STDMETHOD_MOCKn)
  - [**`IN_SEQUENCE(`** *seq...* **`)`**](#IN_SEQUENCE)
  - [**`LR_CO_RETURN(`** *expr* **`)`**](#LR_CO_RETURN)
  - [**`LR_CO_THROW(`** *expr* **`)`**](#LR_CO_THROW)
  - [**`LR_CO_YIELD(`** *expr* **`)`**](#LR_CO_YIELD)
  - [**`LR_RETURN(`** *expr* **`)`**](#LR_RETURN)
  - [**`LR_SIDE_EFFECT(`** *expr* **`)`**](#LR_SIDE_EFFECT)
  - [**`LR_THROW(`** *expr* **`)`**](#LR_THROW)
  - [**`LR_WITH(`** *expr* **`)`**](#LR_WITH)
  - [**`MAKE_CONST_MOCK(`** *func_name*, *signature* **`)`**](#MAKE_CONST_MOCK)
  - [**`MAKE_CONST_MOCKn(`** *func_name*, *signature* **`)`**](#MAKE_CONST_MOCKn)
  - [**`MAKE_MOCK(`** *name*, *signature* **`)`**](#MAKE_MOCK)
  - [**`MAKE_MOCKn(`** *name*, *signature* **`)`**](#MAKE_MOCKn)
  - [**`MAKE_STDMETHOD_MOCK(`** *name*, *signature* **`)`**](#MAKE_STDMETHOD_MOCK)
  - [**`MAKE_STDMETHOD_MOCKn(`** *name*, *signature* **`)`**](#MAKE_STDMETHOD_MOCKn)
  - [**`NAMED_ALLOW_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#NAMED_ALLOW_CALL)
  - [**`NAMED_FORBID_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#NAMED_FORBID_CALL)
  - [**`NAMED_REQUIRE_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#NAMED_REQUIRE_CALL)
  - [**`NAMED_REQUIRE_DESTRUCTION(`** *mock_object* **`)`**](#NAMED_REQUIRE_DESTRUCTION)
  - [**`REQUIRE_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#REQUIRE_CALL)
  - [**`REQUIRE_DESTRUCTION(`** *mock_object* **`)`**](#REQUIRE_DESTRUCTION)
  - [**`RETURN(`** *expr* **`)`**](#RETURN)
  - [**`RT_TIMES(`** *limit* **`)`**](#TIMES-and-RT_TIMES)
  - [**`SIDE_EFFECT(`** *expr* **`)`**](#SIDE_EFFECT)
  - [**`THROW(`** *expr* **`)`**](#THROW)
  - [**`TIMES(`** *limit* **`)`**](#TIMES-and-RT_TIMES)
  - [**`WITH(`** *expr* **`)`**](#WITH)
- [Types and Type Templates](#types_and_templates) (alphabetical order)
  - [`trompeloeil::deathwatched<T>`](#deathwatched_type)
  - [`trompeloeil::expectation`](#expectation_type)
  - [`trompeloeil::expectation_violation`](#expectation_violation_type)
  - [`trompeloeil::lifetime_monitor`](#lifetime_monitor_type)
  - [`trompeloeil::matcher`](#matcher_type)
  - [`trompeloeil::mock_interface<T>`](#mock_interface)
  - [`trompeloeil::ok_reporter_func`](#ok_reporter_func)
  - [`trompeloeil::printer`](#printer)
  - [`trompeloeil::reporter_func`](#reporter_func)
  - [`trompeloeil::sequence`](#sequence_type)
  - [`trompeloeil::severity`](#severity_type)
  - [`trompeloeil::stream_tracer`](#stream_tracer)
  - [`trompeloeil::tracer`](#tracer_type)
  - [`trompeloeil::typed_matcher<T>`](#typed_matcher)
- [Functions and Function Templates](#functions)
  - [`trompeloeil::expectation::is_satisfied()`](#is_satisfied)
  - [`trompeloeil::expectation::is_saturated()`](#is_saturated)
  - [`trompeloeil::get_lock()`](#get_lock)
  - [`trompeloeil::print(std::ostream&, T const&)`](#print)
  - [`trompeloeil::is_null(T const &)`](#is_null)
  - [`trompeloeil::make_matcher<Type>(...)`](#make_matcher)
  - [`trompeloeil::set_reporter(...)`](#set_reporter)
  - [`trompeloeil::sequence::is_completed()`](#is_completed)
- [Constants](#constants)
  - [`trompeloeil_movable_mock`](#movable_mock)

## Notions

### Mock function

A *mock function* is a member function that is mocked with
[**`MAKE_MOCK(name, signature)`**](#MAKE_MOCK),
[**`MAKE_MOCKn(name, signature)`**](#MAKE_MOCKn),
[**`MAKE_CONST_MOCK(name, signature)`**](#MAKE_CONST_MOCK) or
[**`MAKE_CONST_MOCKn(name, signature)`**](#MAKE_CONST_MOCKn).

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
  MAKE_CONST_MOCK(cfunc, auto (std::string, int) -> int);
};
```

Above `C` is a type that has two mock functions `void func(int)` and
`auto cfunc(std::string, int) const -> int`. With a [mock object](#mock_object)
of type `C` it is possible to place [expectations](#expectation)
on the functions `func(...)` and `cfunc(...)`.

### Mock object

A *mock object* is an object of a type that has [mock functions](#mock_function).

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
};

C obj;
```

Above, `obj` is a mock object. It is possible to place
[expectations](#expectation) on [mock functions](#mock_function) for the object
`obj`.

### Expectation

By default it is illegal to call [mock functions](#mock_function). Expectations
change that. Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
};

TEST(atest)
{
  C mock_obj;

  REQUIRE_CALL(mock_obj, func(3));

  tested_function(mock_obj);
}
```

Above `mock_obj` is a [mock object](#mock_object) with one
[mock function](#mock_function) `void func(int)`.

The line [*`REQUIRE_CALL(mock_obj, func(3))`*](#REQUIRE_CALL) places an
expectation that `mock_obj.func(3)` is called before the end of the scope.
Unless `tested_function(mock_obj)` calls `mock_obj.func(3)` a violation is
reported.

The ways to set expectations are:

- [**`REQUIRE_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#REQUIRE_CALL)
- [**`ALLOW_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#ALLOW_CALL)
- [**`FORBID_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#FORBID_CALL)
- [**`NAMED_REQUIRE_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#NAMED_REQUIRE_CALL)
- [**`NAMED_ALLOW_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#NAMED_ALLOW_CALL)
- [**`NAMED_FORBID_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**](#NAMED_FORBID_CALL)

Each **NAMED** variant returns an expectation as
[`std::unique_ptr<trompeloeil::expectation>`](#expectation_type) which can be
saved in variables for storage in test fixtures or other programmatic lifetime
control.

If expectations are not met by the time they go out or scope (or in case of the
**NAMED** variants, when the object held by the `std::unique_ptr<>` is
destroyed) a violation is reported.

By default there is no order imposed on expectations. One way to impose order is
through their lifetimes. Another is by using
[**`IN_SEQUENCE(...)`**](#IN_SEQUENCE).

If there are several expectations that match the same call, they are tried in
the reverse order of creation, and the first found match is accepted. In other
words, the last created matching expectation is the one used.

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
};

using trompeloeil::_;

TEST(atest)
{
  C mock_obj;

  ALLOW_CALL(mock_obj, func(_));
  FORBID_CALL(mock_obj, func(3));
  FORBID_CALL(mock_obj, func(4));

  tested_function(mock_obj);
}
```

Above, the first expectation [**`ALLOW_CALL(...)`**](#ALLOW_CALL) matches
everything using the wildcard [`trompeloeil::_`](#wildcard), but the two
[**`FORBID_CALL(...)`**](#FORBID_CALL) are created later and are thus matched
first. This means that if `tested_function(...)` calls `mock_obj.func(int)` with
`5`, the two [**`FORBID_CALL(...)`**](#FORBID_CALL) do not match, but the
[**`ALLOW_CALL(...)`**](#ALLOW_CALL) does, so the call is allowed. A call with
`3` or `4`, results in a violation is report since a
[**`FORBID_CALL(...)`**](#FORBID_CALL) is matched.

### Matcher

Each parameter in the parameter list of an [expectation](#expectation) can be
an exact value to match for equality (using `operator==`,) or a matcher.
Matchers check a condition on the parameter value. Trompeloeil provides the
matchers

- [_](#wildcard)
- [**`ANY(`** *type* **`)`**](#ANY)
- [**`MEMBER_IS(`** *member*, *matcher* **`)`**](#MEMBER_IS)
- [**`all_of(`** *values* **`)`**](#all_of)
- [**`any_of(`** *values* **`)`**](#any_of)
- [**`eq(`** *value* **`)`**](#eq)
- [**`ne(`** *value* **`)`**](#ne)
- [**`gt(`** *value* **`)`**](#gt)
- [**`ge(`** *value* **`)`**](#ge)
- [**`lt(`** *value* **`)`**](#lt)
- [**`le(`** *value* **`)`**](#le)
- [**`none_of(`** *values* **`)`**](#none_of)
- [**`re(`** *string* **`)`**](#re)
- [**`range_includes(`** *values* **`)`**](#range_includes)
- [**`range_is(`** *values* **`)`**](#range_is)
- [**`range_all_of(`** *matcher* **`)`**](#range_all_of)
- [**`range_any_of(`** *matcher* **`)`**](#range_any_of)
- [**`range_none_of(`** *matcher* **`)`**](#range_none_of)
- [**`range_is_permutation(`** *values* **`)`**](#range_is_permutation)
- [**`range_starts_with(`** *values* **`)`**](#range_starts_with)
- [**`range_ends_with(`** *values* **`)`**](#range_ends_with)

You can also provide [your own matchers](CookBook.md/#custom_matchers).

#### **`_`**

Used in the parameter list of an [expectation](#expectation), `trompeloeil::_`
matches any value of any type.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, int(int));
};

using trompeloeil::_;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, func(_))
    .RETURN(_1 + 1);

  test_function(&mock_obj);
}
```

Above, `mock_obj.func()` is allowed to be called with any value, and it will
return 1 + the value provided.

If type information is needed, for example to disambiguate overloads, use
[**`ANY(`** *type* **`)`**](#ANY).

#### **`MEMBER_IS(`** *member*, *matcher* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a member
of a passed value using a matcher. The matcher can be a value that can be
equality compared with the member, or a matcher like
[**`gt(`** *value* **`)`**](#gt). This es especially useful together with the
matchers [**`all_of(`** *values* **`)`**](#all_of) and
[**`any_of(`** *values* **`)`**](#any_of)

`#include <trompeloeil/matcher/member_is.hpp>`

Example:

```Cpp
struct xy
{
    int x;
    int y;
};

class C
{
public:
  MAKE_MOCK1(func, void(xy));
};

TEST(atest)
{
  C mock_obj;
  REQUIRE_CALL(mock_obj, func(all_of(MEMBER_IS(&xy::x, gt(0)),
                                     MEMBER_IS(&xy::y, 0))));

  test_function(&mock_obj);
}
```

Above, the expectation matches only calls to `mock_obj.fun(xy coord)` with 
`coord.x > 0 && coord.y == 0`.

#### **`ANY(`** *type* **`)`**

Used in the parameter list of an [expectation](#expectation) to match any value
of a specified type. This can be used as an alternative to
[`trompeloeil::_`](#wildcard) when it is important to disambiguate between
overloads.

`#include <trompeloeil/matcher/any.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
  MAKE_MOCK2(func, void(std::string));
};

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, func(ANY(int)));

  test_function(&mock_obj);
}
```

Above, any call to `mock_obj.func(int)` is accepted, but calls to
`mock_obj.func(std::string)` renders a violation report since there is no
matching [expectation](#expectation).

#### **`all_of(`** *values* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
value with all of several provided. By default it matches any parameter type
that supports comparison with the *values*, but an explicit type can be
specified if needed for disambiguation. *values* can be any value that is
equality comparable with the type, or other matchers that can be used with
the type.

`#include <trompeloeil/matcher/set_predicate.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(ifunc, void(int*));
  MAKE_MOCK1(func, void(const char*));
  MAKE_MOCK1(func, void(const std::string&));
};

using trompeloeil::ne;
using trompeloeil::eq;
using trompeloeil::all_of;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, ifunc(all_of(ne(nullptr), *eq(3))));

  std::string expected = "foo";
  REQUIRE_CALL(mock_obj, func(all_of<const char*>(ne(nullptr), expected)));

  test_function(&mock_obj);
}
```

Above, the first [expectation](#expectation) matches only calls to
`mock_obj.ifunc(int*)` with a non-null pointer pointing to the value `3`. Any
call with a `nullptr` or a pointer pointing to a value other than `3` renders
a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches only calls to
`mock_obj.func(const char*)`, with a C-string `"foo"`.

#### **`any_of(`** *values* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
value with any of several provided. By default it matches any parameter type
that supports comparison with the *values*, but an explicit type can be
specified if needed for disambiguation. *values* can be any value that is
equality comparable with the type, or other matchers that can be used with
the type.

`#include <trompeloeil/matcher/set_predicate.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(ifunc, void(int*));
  MAKE_MOCK1(func, void(const char*));
  MAKE_MOCK1(func, void(const std::string&));
};

using trompeloeil::ne;
using trompeloeil::eq;
using trompeloeil::any_of;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, ifunc(any_of(nullptr, *eq(3))));

  std::string expected = "foo";
  REQUIRE_CALL(mock_obj, func(any_of<const char*>(nullptr, expected)));

  test_function(&mock_obj);
}
```

Above, the first [expectation](#expectation) matches only calls to
`mock_obj.ifunc(int*)` with either a `nullptr`, or a pointer to the value
`3`. Any call with a non-null pointer pointing to a value other than `3`
renders a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches only calls to
`mock_obj.func(const char*)`, with either `nullptr` or a C-string `"foo"`.

#### **`eq(`** *value* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
value equal to the one provided. By default it matches any parameter type
that supports `operator==()` with the value, but an explicit type can be
specified if needed for disambiguation.

`#include <trompeloeil/matcher/compare.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int*));
  MAKE_MOCK1(func, void(const char*));
  MAKE_MOCK1(func, void(const std::string&));
};

using trompeloeil::eq;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, func(*eq(3)));

  std::string expected = "foo";
  REQUIRE_CALL(mock_obj, func(eq<const char*>(expected)));

  test_function(&mock_obj);
}
```

Above, the first [expectation](#expectation) matches only calls to
`mock_obj.func(int*)` with a non-null pointer pointing to the value `3`. Any
call with a `nullptr` or a pointer pointing to a value other than `3` renders
a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches only calls to
`mock_obj.func(const char*)`, with a C-string `"foo"`.

#### **`ne(`** *value* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
value not equal to the one provided. By default it matches any parameter type
that supports `operator!=()` with the value, but an explicit type can be
specified if needed for disambiguation.

`#include <trompeloeil/matcher/compare.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(const char*));
  MAKE_MOCK1(func, void(const std::string&));
};

using trompeloeil::ne;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, func(ne(nullptr)));
  REQUIRE_CALL(mock_obj, func(ne<std::string>("")));
  test_function(&mock_obj);
}
```

Above, the first [expectation](#expectation) matches only calls to
`mock_obj.func(const char*)` with non-null pointer. Any call with a `nullptr`
renders a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches only calls to
`mock_obj.func(const std::string&)`, with a non-empty string.

It is also possible to use `*ne(val)` to match a pointer to a non-equal value.

#### **`gt(`** *value* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
value greater than the one provided. By default it matches any parameter type
that supports `operator>()` with the value, but an explicit type can be
specified if needed for disambiguation.

`#include <trompeloeil/matcher/compare.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(short));
  MAKE_MOCK1(func, void(int));
  MAKE_MOCK1(func, void(std::string));
};

using trompeloeil::gt;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, func(gt<short>(0)));
  ALLOW_CALL(mock_obj, func(gt("foo")));

  test_function(&mock_obj);
}
```

Above, the first [expectation](#expectation) matches only calls to
`mock_obj.func(short)` with positive values. Any call with 0 or negative, and
any calls to `mock_obj.func(int)` renders a violation report since no
[expectation](#expectation) matches.

The second [expectation](#expectation) matches calls to
`mock_obj.func(std::string)`, since
[`std::string`](http://en.cppreference.com/w/cpp/string/basic_string) is
greater-than comparable with a string literal.

It is also possible to use `*gt(val)` to match a pointer to a greater-than
value.

#### **`ge(`** *value* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
value greater than on equal to the one provided. By default it matches any
parameter type that supports `operator>=()` with the value, but an explicit
type can be specified if needed for disambiguation.

`#include <trompeloeil/matcher/compare.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
  MAKE_MOCK1(func, void(short));
  MAKE_MOCK1(func, void(std::string));
};

using trompeloeil::ge;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, func(ge<short>(0)));
  REQUIRE_CALL(mock_obj, func(ge("foo")));

  test_function(&mock_obj);
}
```

Above, the first [expectation](#expectation) matches only calls to
`mock_obj.func(short)` with zero or positive values. Any call with a negative
value renders a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches only calls to
`mock_obj.func(std::string)`, since
[`std::string`](http://en.cppreference.com/w/cpp/string/basic_string) is
greater-than-or-equal-to comparable with string literal.

It is also possible to use `*ge(val)` to match a pointer to a greater-than or
equal value.

#### **`lt(`** *value* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
value less than the one provided. By default it matches any parameter type
that supports `operator<()` with the value, but an explicit type can be
specified if needed for disambiguation.

`#include <trompeloeil/matcher/compare.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(long));
  MAKE_MOCK1(func, void(int));
  MAKE_MOCK1(func, void(const std::string&));
};

using trompeloeil::lt;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, func(lt<int>(0)));
  REQUIRE_CALL(mock_obj, func(lt("foo")));

  test_function(&mock_obj);
}
```

Above, the first [expectation](#expectation) matches only calls to
`mock_obj.func(int)` with negative values. Any call with 0 or positive
renders a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches calls to
`mock_obj.func(cost std::string&)`, since
[`std::string`](http://en.cppreference.com/w/cpp/string/basic_string) is
less-than comparable with string a literal.

It is also possible to use `*lt(val)` to match a pointer to a less-than value.

#### **`le(`** *value* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
value less than or equal to the one provided. By default it matches any
parameter type that supports `operator<=()` with the value, but an explicit type
can be specified if needed for disambiguation.

`#include <trompeloeil/matcher/compare.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
  MAKE_MOCK1(func, void(short));
  MAKE_MOCK1(func, void(const char*));
};

using trompeloeil::le;
using std::string_literals;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, func(le<short>(0)));
  REQUIRE_CALL(mock_obj, func(le("foo"s)));
  test_function(&mock_obj);
}
```

Above, first the [expectation](#expectation) matches only calls to
`mock_obj.func(short)` with zero or negative values. Any call with a positive
value renders a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches calls to
`mock_obj.func(const char*)`, since a c-string is less-than comparable
with a [`std::string`](http://en.cppreference.com/w/cpp/string/basic_string)

It is also possible to use `*le(val)` to match a pointer to a less-than or
equal value.

#### **`none_of(`** *values* **`)`**

Used in the parameter list of an [expectation](#expectation) to ensure no
match between a value and several provided. By default it matches any
parameter type that supports comparison with the *values*, but an explicit
type can be specified if needed for disambiguation. *values* can be any value
that is equality comparable with the type, or other matchers that can be used
with the type.

`#include <trompeloeil/matcher/set_predicate.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(ifunc, void(int*));
  MAKE_MOCK1(func, void(const char*));
  MAKE_MOCK1(func, void(const std::string&));
};

using trompeloeil::ne;
using trompeloeil::eq;
using trompeloeil::none_of;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, ifunc(none_of(nullptr, *eq(3))));

  std::string expected = "foo";
  REQUIRE_CALL(mock_obj, func(none_of<const char*>(nullptr, expected)));

  test_function(&mock_obj);
}
```

Above, the first [expectation](#expectation) matches only calls to
`mock_obj.ifunc(int*)` with a non-null pointer pointer to a value other than
`3`. Any call with a `nullptr`, or a pointer pointing to the value `3`
renders a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches only calls to
`mock_obj.func(const char*)`, with a non-null pointer, pointing to a C-string
that is not `"foo"`.

#### **`re(`** *string* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
string with a regular expression.

`#include <trompeloeil/matcher/re.hpp>`

**`re()`** exists in two flavours.

- **`re(`** *string*, *flags...* **`)`**
  which can match both C-strings (`char*`, `const char*`) as well as
  `C++` `std::string`.
- **`re<type>(`** *string*, *flags...* **`)`**
  which can be used to disambiguate overloads.

For both versions, the string can be either `std::string` or a C-string.

*flags...* can be

- empty
- `std::regex_constants::syntax_option_type`
- `std::regex_constants::match_flag_type`
- `std::regex_constants::syntax_option_type, std::regex_constants::match_flag_type`

Regular expression matching is made with
[`std::regex_search()`](http://en.cppreference.com/w/cpp/regex/regex_search)

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(unique, void(std::string&));
  MAKE_MOCK1(overloaded, void(const char*));
  MAKE_MOCK1(overloaded, void(const std::string&));
};

using trompeloeil::re;

TEST(atest)
{
  C mock_obj;
  REQUIRE_CALL(mock_obj, unique(re("end$", std::regex_constants::icase)));
  REQUIRE_CALL(mock_obj, overloaded(re<const char*>("end", std::regex_constants::match_not_eol)));
  test_function(&mock_obj);
}
```

Above, `test_function(&mock_obj)` must call `mock_obj.unique()` with a string
case insensitively matching the regular expression `/end$/`, and also call
`mock_obj.overloaded(const char*)` with a regular expression matching
the regular expression `/end/`.

It is also possible to use `*re(string)` to match a pointer to a string with
a regular expression, or `!re(string)` to allow only strings that do not match
a regular expression.

#### **`range_includes(`** matchers **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
range with has a set of matchers. By default it can match any range-like
type, but it can be explicitly disambiguated by providing a type to match for.

`#include <trompeloeil/matcher/range.hpp>`

**`range_includes`** comes in two flavours:
* **`range_includes(`** *matchers* **`)`** where matchers is one or several values or other matchers like [**`re(`** *string* **`)`**](#re)
* **`range_includes(`** *values* **`)`** where values is a collection, e.g. a [`std::vector<>`](https://en.cppreference.com/w/cpp/container/vector) or C-array, of values.

Example using matchers:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::list<int>&));
};

using trompeloeil::gt;
using trompeloeil::range_includes;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, vfunc(range_includes(gt(2), 1)));
  REQUIRE_CALL(mock_obj, ofunc(range_includes<std::list<int>>(1,2,3)));
  test_function(&mock_obj);
}
```

Above, first the [expectation](#expectation) matches only calls to
`mock_obj.vfunc(const std::vector<int>&)` which has at least one element
`== 1`, and at least one element `> 2`. Any call with a different set of
values renders a violation report since no [expectation](#expectation)
matches.

The second [expectation](#expectation) matches calls to
`mock_obj.ofunc(const std::list<int>&)` with at least the values
`{ 1, 2, 3 }` (in any order).

Example using a C-array of values:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
};

using trompeloeil::range_includes;

TEST(atest)
{
  C mock_obj;
  int values[] {2, 1 };
  ALLOW_CALL(mock_obj, vfunc(range_includes(values)));
  test_function(&mock_obj);
}
```

The expectation only matches calls to `mock_obj.vfunc()` with a vector that
holds at least one elemend with the value 1, and at least one element with
the value 2.

#### **`range_is(`** *matchers* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
range with a set of matchers. By default it can match any range-like
type, but it can be explicitly disambiguated by providing a type to match for.

`#include <trompeloeil/matcher/range.hpp>`

**`range_is`** comes in two flavours:
* **`range_is(`** *matchers* **`)`** where matchers is one or several values or other matchers like [**`re(`** *string* **`)`**](#re)
* **`range_is(`** *values* **`)`** where values is a collection, e.g. a [`std::vector<>`](https://en.cppreference.com/w/cpp/container/vector) or C-array, of values.

Example using matchers:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::list<int>&));
};

using trompeloeil::le;
using trompeloeil::range_is;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, vfunc(range_is(1, 3, le(0))));
  REQUIRE_CALL(mock_obj, ofunc(range_is<std::list<int>>(1,2,3)));
  test_function(&mock_obj);
}
```

Above, first the [expectation](#expectation) matches only calls to
`mock_obj.vfunc(const std::vector<int>&)` with the values `{ 1, 3, x }`,
where `x <= 0`. Any call with a different set of values
renders a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches calls to
`mock_obj.ofunc(const std::list<int>&)` with the values `{ 1, 2, 3 }`.

Example using C-array of values:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
};

using trompeloeil::range_is;

TEST(atest)
{
  C mock_obj;
  int expected[] { 1, 2, 3 };
  ALLOW_CALL(mock_obj, vfunc(range_is(expected)));
  test_function(&mock_obj);
}
```

The expectation only matches calls to `mock_obj.vfunc()` with a vector holding exactly { 1, 2, 3 }.

#### **`range_all_of(`** *matcher* **`)`**

Used in the parameter list of an [expectation](#expectation) to match each
element in a range to a matcher or value. By default it can match any
range-like  type, but it can be explicitly disambiguated by providing a
type to match for.

`#include <trompeloeil/matcher/range.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::list<int>&));
};

using trompeloeil::gt;
using trompeloeil::range_all_of;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, vfunc(range_all_of(gt(0))));
  REQUIRE_CALL(mock_obj, ofunc(range_all_of<std::list<int>>(gt(0))));
  test_function(&mock_obj);
}
```

Above, first the [expectation](#expectation) matches only calls to
`mock_obj.vfunc(const std::vector<int>&)` with values `> 0`,
Any call with a different set of values
renders a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches calls to
`mock_obj.ofunc(const std::list<int>&)` with values `> 0`.

The matcher `range_all_of` always matches an empty range.

#### **`range_any_of(`** *matcher* **`)`**

Used in the parameter list of an [expectation](#expectation) to match each
element in a range to a matcher or value. By default it can match any
range-like  type, but it can be explicitly disambiguated by providing a
type to match for.

`#include <trompeloeil/matcher/range.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::list<int>&));
};

using trompeloeil::gt;
using trompeloeil::range_any_of;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, vfunc(range_any_of(gt(0))));
  REQUIRE_CALL(mock_obj, ofunc(range_any_of<std::list<int>>(gt(0))));
  test_function(&mock_obj);
}
```

Above, first the [expectation](#expectation) matches only calls to
`mock_obj.vfunc(const std::vector<int>&)` with at least one values `> 0`,
Any call with a different set of values
renders a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches calls to
`mock_obj.ofunc(const std::list<int>&)` with at least one value `> 0`.

The matcher `range_any_of` does never match an empty range.

#### **`range_none_of(`** *matcher* **`)`**

Used in the parameter list of an [expectation](#expectation) to match each
element in a range to a matcher or value. By default it can match any
range-like  type, but it can be explicitly disambiguated by providing a
type to match for.

`#include <trompeloeil/matcher/range.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::list<int>&));
};

using trompeloeil::lt;
using trompeloeil::range_none_of;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, vfunc(range_none_of(0)));
  REQUIRE_CALL(mock_obj, ofunc(range_none_of<std::list<int>>(lt(0))));
  test_function(&mock_obj);
}
```

Above, first the [expectation](#expectation) matches only calls to
`mock_obj.vfunc(const std::vector<int>&)` where none of the values are `0`,
Any call with a at least one value `== 0` renders a violation report since
no [expectation](#expectation) matches.

The second [expectation](#expectation) matches calls to
`mock_obj.ofunc(const std::list<int>&)` where none of the values are `< 0`.

The matcher `range_none_ofl` always matches an empty range.

#### **`range_is_permutation(`** *matchers* **`)`**

Used in the parameter list of an [expectation](#expectation) to match a
range with a set of matchers without regard to order. By default it can
match any range-like type, but it can be explicitly disambiguated by
providing a type to match for.

`#include <trompeloeil/matcher/range.hpp>`

**`range_is_permutation`** comes in two flavours:
* **`range_is_permutation(`** *matchers* **`)`** where matchers is one or several values or other matchers like [**`re(`** *string* **`)`**](#re)
* **`range_is_permutation(`** *values* **`)`** where values is a collection, e.g. a [`std::vector<>`](https://en.cppreference.com/w/cpp/container/vector) or C-array, of values. 

Example using matchers:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::list<int>&));
};

using trompeloeil::le;
using trompeloeil::range_is_permutation;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, vfunc(range_is_permutation(le(0), 1, 3)));
  REQUIRE_CALL(mock_obj, ofunc(range_is_permutation<std::list<int>>(1,2,3)));
  test_function(&mock_obj);
}
```

Above, first the [expectation](#expectation) matches only calls to
`mock_obj.vfunc(const std::vector<int>&)` with some permutation of the values
`{ 1, 3, x }`, where `x <= 0`. Any call with a different set of values
renders a violation report since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches calls to
`mock_obj.ofunc(const std::list<int>&)` with a permutation of the values
`{ 1, 2, 3 }`.

**NOTE!** Avoid using `range_is_permutation` with relational matchers like
[**`gt(`** *value* **`)`**](#gt). In order to work with input-ranges, it
uses a greedy one-pass algorithm, which may reach different results
depending  on the order in which the elements are matched. E.g.
`range_is_permutation(gt(0), gt(1), gt(2))` may or may not match a range
`{3,2,1}`.

Example using a C-array of values:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
};

using trompeloeil::range_is_permutation;

TEST(atest)
{
  C mock_obj;
  int values[] { 1, 2, 3 };
  ALLOW_CALL(mock_obj, vfunc(range_is_permutation(values)));
  test_function(&mock_obj);
}
```

This only allows calls to `mock_obj.vfunc()` with a vector holding the values
1, 2, 3, in any order. 

#### **`range_starts_with(`** *matchers* **`)`**

Used in the parameter list of an [expectation](#expectation) to match the
first values in a range to a set of matchers. By default it can match any
range-like  type, but it can be explicitly disambiguated by providing a type
to match for.

`#include <trompeloeil/matcher/range.hpp>`

**`range_starts_with`** comes in two flavours:
* **`range_starts_with(`** *matchers* **`)`** where matchers is one or several values or other matchers like [**`re(`** *string* **`)`**](#re)
* **`range_starts_with(`** *values* **`)`** where values is a collection, e.g. a [`std::vector<>`](https://en.cppreference.com/w/cpp/container/vector) or C-array, of values.

Example using matchers:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::list<int>&));
};

using trompeloeil::le;
using trompeloeil::range_starts_with;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, vfunc(range_starts_with(1, le(0))));
  REQUIRE_CALL(mock_obj, ofunc(range_starts_with<std::list<int>>(1,2)));
  test_function(&mock_obj);
}
```

Above, first the [expectation](#expectation) matches only calls to
`mock_obj.vfunc(const std::vector<int>&)` with a vector holding at
least two elements, starting with `{ 1, x, }`, where `x <= 0`.
Any call with a different set of values renders a violation report
since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches calls to
`mock_obj.ofunc(const std::list<int>&)` with at least two values,
starting with `{ 1, 2 }`.

Example using a C-array with values:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
};

using trompeloeil::range_starts_with;

TEST(atest)
{
  C mock_obj;
  int first_values[]{1,2};
  ALLOW_CALL(mock_obj, vfunc(range_starts_with(first_values)));
  test_function(&mock_obj);
}
```

The example above matches only calls to `mock_obj.vfunc()` with a vector
which starts with the values {1, 2}.

#### **`range_ends_with(`** *matchers* **`)`**

Used in the parameter list of an [expectation](#expectation) to match the
last values in a range to a set of matchers. By default it can match any
range-like  type, but it can be explicitly disambiguated by providing a type
to match for.

`#include <trompeloeil/matcher/range.hpp>`

**`range_ends_with`** comes in two flavours:
* **`range_ends_with(`** *matchers* **`)`** where matchers is one or several values or other matchers like [**`re(`** *string* **`)`**](#re)
* **`range_ends_with(`** *values* **`)`** where values is a collection, e.g. a [`std::vector<>`](https://en.cppreference.com/w/cpp/container/vector) or C-array, of values.

Example using matchers:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::vector<int>&));
  MAKE_MOCK1(ofunc, void(const std::list<int>&));
};

using trompeloeil::le;
using trompeloeil::range_ends_with;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, vfunc(range_ends_with(1, le(0))));
  REQUIRE_CALL(mock_obj, ofunc(range_ends_with<std::list<int>>(1,2)));
  test_function(&mock_obj);
}
```

Above, first the [expectation](#expectation) matches only calls to
`mock_obj.vfunc(const std::vector<int>&)` with a vector holding at
least two elements, ending with `{ 1, x, }`, where `x <= 0`.
Any call with a different set of values renders a violation report
since no [expectation](#expectation) matches.

The second [expectation](#expectation) matches calls to
`mock_obj.ofunc(const std::list<int>&)` with at least two values,
ending with `{ 1, 2 }`.

Example using a C-array of values:

```Cpp
class C
{
public:
  MAKE_MOCK1(vfunc, void(const std::vector<int>&));
};

using trompeloeil::range_ends_with;

TEST(atest)
{
  C mock_obj;
  int tail[]{2,1,0};
  ALLOW_CALL(mock_obj, vfunc(range_ends_with(tail)));
  test_function(&mock_obj);
}
```

The example above only matches calls to `mock_obj.vfunc()` with a vector with
2,1,0 as the last elements.

#### **`*`** *matcher*

Used in the parameter list of an [expectation](#expectation) together with a
matcher, to match a value pointed to by a pointer. A
[`nullptr`](http://en.cppreference.com/w/cpp/language/nullptr) value fails the
matcher.

`#include <trompeloeil/matcher/deref.hpp>`

Example:

```Cpp
struct C {
  MAKE_MOCK1(func, void(int*));
};

using trompeloeil::eq; // matching equal values

TEST(atest)
{
  C mock_obj;
  REQUIRE_CALL(mock_obj, func(*eq(3)));
  test_function(&mock_obj);
}
```

Above, `test_function(&mock_obj)` must call `mock_obj.func()` with a pointer
to the value `3`.

#### **`!`** *matcher*

Used in the parameter list of an [expectation](#expectation) together with a
matcher, to negate a matcher, i.e. to fail what the matcher allows, and to
allow what the matcher fails.

`#include <trompeloeil/matcher/not.hpp>`

Example:

```Cpp
struct C {
  MAKE_MOCK1(func, void(const std::string&));
};

using trompeloeil::re; // matching regular expressions

TEST(atest)
{
  C mock_obj;
  REQUIRE_CALL(mock_obj, func(!re("^foo")));
  test_function(&mock_obj);
}
```

Above, `test_function(&mock_obj)` must call `mock_obj.func()` with a string
that does not begin with `"foo"`.

## Macros

### **`ALLOW_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**

Make an expectation that *mock_object*.*func_name*(*parameter_list*) may be
called zero or more times until the end of the surrounding scope.
*parameter_list* may contain exact values or [matchers](#matcher)
that describes matching calls.

This is the same as
[**`REQUIRE_CALL(...)`**](#REQUIRE_CALL).[**`TIMES(`**](#TIMES) 0,infinity **`)`**.

`#include <trompeloeil/mock.hpp>`

Matches any number of times, but is not required to match. (_actually the limit is
0..~0ULL, but that is for all practical purposes "infinity"_)

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, int(int));
};

using trompeloeil::_;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, func(_))
    .RETURN(_1 + 1);

  test_function(&mock_obj);
}
```

Above **`ALLOW_CALL(mock_obj, func(_))`** places an expectation that
`mock_obj.func()` may be called any number of times with any parameter value
and will always return the parameter value + 1. `test_function(...)`
is allowed to call `mock_obj.func()` any number of times (including no call at
all).

The expectation is valid until the end of the scope, which in the example above
is until after the return from `test_function(...)`.

See also [**`NAMED_ALLOW_CALL(...)`**](#NAMED_ALLOW_CALL) which creates an
expectation as a
[`std::unique_ptr<trompeloeil::expectation>`](#expectation_type) which can be
stored in test fixtures or otherwise have its lifetime programmatically controlled.

### **`ANY(`** *type* **`)`**

A [matcher](#matcher) for use in the parameter list of an
[expectation](#expectation) to disambiguate overloaded functions on type when
the exact value is unimportant. See the matcher [**`ANY(`** *type* **`)`**](#ANY) above.

`#include <trompeloeil/matcher/any.hpp>`

### **`AT_LEAST(`** *number* **`)`**

Used in [**`TIMES(...)`**](#TIMES) to set the range *number*..infinity.
*number* must be
[`constexpr`](http://en.cppreference.com/w/cpp/language/constexpr).

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
};

using trompeloeil::_;

TEST(atest)
{
  C mock_obj;
  REQUIRE_CALL(mock_obj, func(_))
    .TIMES(AT_LEAST(3));
  tested_function(&mock_obj);
}
```

Above, the line [**`TIMES(`**](#TIMES)**`AT_LEAST(3))`** modifies the
[expectation](#expectation) such that *mock_obj.func()* must be called 3 times
or more, before the end of the scope, or a violation is reported.

_In reality the upper limit is ~0ULL, but that is for all practical purposes
"infinity"_.

### **`AT_MOST(`** *number* **`)`**

Used in [**`TIMES(...)`**](#TIMES) to set the range 0..*number*.
*number* must be
[`constexpr`](http://en.cppreference.com/w/cpp/language/constexpr).

`#include <trompeloeil/mock.hpp>`


Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
};

using trompeloeil::_;

TEST(atest)
{
  C mock_obj;
  REQUIRE_CALL(mock_obj, func(_))
    .TIMES(AT_MOST(3));
  tested_function(&mock_obj);
}
```

Above, the line [**`TIMES(`**](#TIMES)**`AT_MOST(3))`** modifies the
[expectation](#expectation) such that *mock_obj.func()* must be called 3 times
or less (including no call at all) before the end of the scope, or a violation
is reported.

### **`CO_RETURN(`** *expr* **`)`**

Used in [expectations](#expectation) to set the return value from a coroutine.
Note that when [**`SIDE_EFFECT(...)`**](#SIDE_EFFECT) and
[**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT) are executed depends on the behaviour of the
coroutine promise  type. This code may alter out-parameters.

`#include <trompeloeil/coro.hpp>`

Coroutines are supported if the compiler defines the
[**`__cpp_impl_coroutines`**](https://eel.is/c++draft/cpp.predefined#:__cpp_impl_coroutine)
feature test macro.

**NOTE!** Be very extra careful with lifetime issues when dealing with coroutines.

### **`CO_THROW(`** *expr* **`)`**

Used in [expectations](#expectation) to throw an exception from a coroutine.
Note that when any [**`SIDE_EFFECT(...)`**](#SIDE_EFFECT) and
[**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT) are executed depends on the behaviour of the
coroutine promise type. This code may alter out-parameters.

`#include <trompeloeil/coro.hpp>`

Coroutines are supported if the compiler defines the
[**`__cpp_impl_coroutines`**](https://eel.is/c++draft/cpp.predefined#:__cpp_impl_coroutine)
feature test macro.

**NOTE!** Be very extra careful with lifetime issues when dealing with coroutines.

### **`CO_YIELD(`** *expr* **`)`**

Used in [expectations](#expectation) with a coroutine type that can
[`co_yield`](https://en.cppreference.com/w/cpp/language/coroutines#co_yield).
You can add several **`CO_YIELD`** to the same expectation, and the values will
be yielded one at the time, in the order they are listed. Note that
[**`CO_RETURN(`** *expr* **`)`**](#CO_RETURN) or
[**`LR_CO_RETURN(`** *expr* **`)`**](#LR_CO_RETURN) is still needed.

See also [**`LR_CO_YIELD(`** *expr* **`]`**](#LR_CO_YIELD)

`#include <trompeloeil/coro.hpp>`

Coroutines are supported if the compiler defines the
[**`__cpp_impl_coroutines`**](https://eel.is/c++draft/cpp.predefined#:__cpp_impl_coroutine)
feature test macro.

**NOTE!** Be very extra careful with lifetime issues when dealing with coroutines.

### **`FORBID_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**

Make an expectation that *mock_object*.*func_name*(*parameter_list*) must not
be called until the end of the scope. *parameter_list* may contain exact values
or [matchers](#matcher) that describes matching calls.

This is the same as
[**`REQUIRE_CALL(...)`**](#REQUIRE_CALL).[**`TIMES(`**](#TIMES) 0 **`)`**,
making any matching call an error. This is often done in a narrow scope
where the wider scope would allow the call. [**`LR_RETURN(...)`**](#LR_RETURN),
[**`RETURN(...)`**](#RETURN), [**`LR_THROW(...)`**](#LR_THROW) and
[**`THROW(...)`**](#THROW) are illegal in a **`FORBID_CALL(...)`**.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
};

using trompeloeil::_;

TEST(atest)
{
  C mock_obj;
  ALLOW_CALL(mock_obj, func(_));

  tested_function(1, &mock_obj);

  {
    FORBID_CALL(mock_obj, func(2));

    tested_function(2, &mock_obj);
  }

  tested_function(3, &mock_obj);
}
```

Above, the [mock function](#mock_function) *C::func(int)* may be called with any
value for *mock_obj*, except in the scope of the *tested_function(2, &mock_obj)*,
where *mock_obj.func(2)* would lead to a violation being reported. At
*tested_function(3, &mock_obj)* any value is allowed again.

See also [**`NAMED_FORBID_CALL(...)`**](#NAMED_FORBID_CALL) which creates an
expectation as a
[`std::unique_ptr<trompeloeil::expectation>`](#expectation_type) which can be
stored in test fixtures or otherwise have its lifetime programmatically controlled.

### **`IMPLEMENT_CONST_MOCKn(`** *func_name* {, *specifiers* } **`)`**

Make a `const` [mock function](#mock_function) implementation of the
`virtual` function named *func_name* from the inherited interface. This macro
is only usable with `virtual` non-`final` functions, and only when used with
[`mock_interface<T>`](#mock_interface), where `T` is the interface.

*specifiers* is an optional list which may include attributes or specifiers like
[`noexcept`](https://en.cppreference.com/w/cpp/language/noexcept_spec).

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class I
{
public:
  virtual ~I() = default;
  virtual int func(int, const std::vector<int>&)) const = 0;
};

class C : public trompeloeil::mock_interface<I>
{
public:
  IMPLEMENT_CONST_MOCK2(func);
};
```

Above, class `C` will effectively become:

```Cpp
class C : public trompeloeil::mock_interface<I>
{
public:
  int func(int, const std::vector<int>&) const override;
};
```

It is not possible to mock operators, constructors or the destructor, but
you can call [mock functions](#mock_function) from those.

**NOTE!** **`IMPLEMENT_CONST_MOCKn(...)`** cannot handle overloaded functions.

See also [**`IMPLEMENT_MOCKn(...)`**](#IMPLEMENT_MOCKn) for non-`const`
member functions.

See also [**`MAKE_MOCK(...)`**](#MAKE_MOCK),
[**`MAKE_MOCKn(...)`**](#MAKE_MOCKn),
[**`MAKE_CONST_MOCK(...)`**](#MAKE_CONST_MOCK) and
[**`MAKE_CONST_MOCKn(...)`**](#MAKE_CONST_MOCKn) for making mock implementations
of any member functions.

### **`IMPLEMENT_MOCKn(`** *func_name* {, *specifiers* } **`)`**

Make a non-`const` [mock function](#mock_function) implementation of the
`virtual` function named *func_name* from the inherited interface. This macro
is only usable with `virtual` non-`final` functions, and only when used with
[`mock_interface<T>`](#mock_interface), where `T` is the interface.

*specifiers* is an optional list which may include attributes or specifiers like
[`noexcept`](https://en.cppreference.com/w/cpp/language/noexcept_spec).

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class I
{
public:
  virtual ~I() = default;
  virtual int func(int, const std::vector<int>&)) = 0;
};

class C : public trompeloeil::mock_interface<I>
{
public:
  IMPLEMENT_MOCK2(func1);
};
```

Above, class `C` will effectively become:

```Cpp
class C : public trompeloeil::mock_interface<I>
{
public:
  int func(int, const std::vector<int>&) override;
};
```

It is not possible to mock operators, constructors or the destructor, but
you can call [mock functions](#mock_function) from those.

**NOTE!** **`IMPLEMENT_MOCKn(...)`** cannot handle overloaded functions.

See also [**`IMPLEMENT_CONST_MOCKn(...)`**](#IMPLEMENT_CONST_MOCKn) for `const`
member functions.

See also [**`MAKE_CONST_MOCKn(...)`**](#MAKE_CONST_MOCKn) for `const`
member functions.

### **`IMPLEMENT_STDMETHOD_MOCKn(`** *func_name* {, *specifiers* } **`)`**

Make a `STDMETHODCALLTYPE` [mock function](#mock_function) implementation of the
`virtual` function named *func_name* from the inherited interface. This macro
is only usable with `virtual` non-`final` functions, and only when used with
[`mock_interface<T>`](#mock_interface), where `T` is the interface.

*specifiers* is an optional list which may include attributes or specifiers like
[`noexcept`](https://en.cppreference.com/w/cpp/language/noexcept_spec).

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class I
{
public:
  virtual ~I() = default;
  virtual int STDMETHODCALLTYPE func(int, const std::vector<int>&)) const = 0;
};

class C : public trompeloeil::mock_interface<I>
{
public:
  IMPLEMENT_STDMETHOD_MOCK2(func);
};
```

Above, class `C` will effectively become:

```Cpp
class C : public trompeloeil::mock_interface<I>
{
public:
  int STDMETHODCALLTYPE func(int, const std::vector<int>&) const override;
};
```

It is not possible to mock operators, constructors or the destructor, but
you can call [mock functions](#mock_function) from those.

**NOTE!** **`IMPLEMENT_STDMETHOD_MOCKn(...)`** cannot handle overloaded functions.

**NOTE!** **`IMPLEMENT_STDMETHOD_MOCKn(...)`** only works on Windows.

See also [**`MAKE_STDMETHOD_MOCKn(...)`**](#MAKE_STDMETHOD_MOCKn)

### **`IN_SEQUENCE(`** *seq...* **`)`**

Where *seq...* is one or more instances of `trompeloeil::sequence`. Impose an
order in which [expectations](#expectation) and destruction of
[**`deathwatched_type`**](#deathwatched_type) objects must match.
Several sequences can be parallel and interleaved. A sequence for an
[expectation](#expectation) can move forward to the next once the lower
limit from [**`TIMES(...)`**](#TIMES) is reached (defaults to 1). This means
that if the lower limit is 0 (see [**`ALLOW_CALL(...)`**](#ALLOW_CALL)), the
expectation may be skipped in the sequence.

`#include <trompeloeil/sequence.hpp>`

Example:

```Cpp
class Mock
{
public:
  MAKE_MOCK1(func, void(int));
  MAKE_MOCK1(func, void(const std::string&));
};

class ephemeral
{
public:
  virtual ~ephemeral() {};
};

TEST(atest)
{
  Mock m[2];
  auto e = new trompeloeil::deathwatched<ephemeral>;

  trompeloeil::sequence seq1, seq2;

  REQUIRE_CALL(m[0], func(ANY(int))
    .IN_SEQUENCE(seq1, seq2);

  REQUIRE_CALL(m[0], func(ANY(const std::string&))
    .IN_SEQUENCE(seq1);

  REQUIRE_CALL(m[1], func(ANY(const std::string&))
    .IN_SEQUENCE(seq2);

  REQUIRE_CALL(m[1], func(ANY(int))
    .IN_SEQUENCE(seq1, seq2);

  REQUIRE_DESTRUCTION(*e)
    .IN_SEQUENCE(seq1, seq2);

  tested_func(&m[0], &m[1], e);
}
```

All sequence objects are listed in the first [**`REQUIRE_CALL(...)`**](#REQUIRE_CALL),
thus it must be the first [expectation](#expectation) matched. Likewise all
sequences are listed in the last
[**`REQUIRE_CALL(...)`**](#REQUIRE_CALL), so it must be last
[expectation](#expectation) matched. The intermediate
[expectations](#expectation) has one sequence object each, thus they have no
matching order imposed between them. Last of all is the
[**`REQUIRE_DESTRUCTION(...)`**](#REQUIRE_DESTRUCTION), which also lists
all sequence objects and must happen after all other
[expectations](#expectation) are fulfilled.

The above allows the following two sequences only.

- `m[0].func(int)` -> `m[0].func(string)` -> `m[1].func(string)` -> `m[1].func(int)` -> `delete e`
- `m[0].func(int)` -> `m[1].func(string)` -> `m[0].func(string)` -> `m[1].func(int)` -> `delete e`

Any other sequence of calls renders a violation report.

Note that `.IN_SEQUENCE()` in combination with [**`.TIMES(...)`**](#TIMES) is
greedy. It will stay on  on the same expectation as long as it matches, and
will leave for the next step in the sequence only when the upper bound from
[**`.TIMES(...)`**](#TIMES) is reached, or a different expectation matches.

Example:

```Cpp
class Mock
{
public:
  MAKE_MOCK1(func, void(int));
};

TEST(a_test)
{
  Mock m;
  trompeloeil::sequence seq;
  
  REQUIRE_CALL(m, func(0))
    .IN_SEQUENCE(seq)
    .TIMES(1, 5);
  
  ALLOW_CALL(m, func(0))
    .IN_SEQUENCE(seq)
    .SIDE_EFFECT(std::cout << "extra\n");
  
  REQUIRE_CALL(m, func(1))
    .IN_SEQUENCE(seq);
  
  test_func(m);
}
```

The expectation `REQUIRE_CALL(m, func(0))` stays in effect until either matched
5 times, or a call to `m.func(1)` has been made. After a call to `m.func(1)`,
no call to `m.func(0)` is allowed.

The function `test_func()` must call `m.func(0)` at least once, and end with
`m.func(1)`. If `m.func(0)` is called more than 5 times, each call prints
`"extra"` on `std::cout`.

### **`LR_CO_RETURN(`** *expr* **`)`**

Used in [expectations](#expectation) to set the return value from a coroutine.
Note that when any [**`SIDE_EFFECT(...)`**](#SIDE_EFFECT) and
[**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT) are executed depends on the behaviour of the
coroutine promise type. This code may alter out-parameters.

`#include <trompeloeil/coro.hpp>`

Coroutines are supported if the compiler defines the
[**`__cpp_impl_coroutines`**](https://eel.is/c++draft/cpp.predefined#:__cpp_impl_coroutine)
feature test macro.

**NOTE!** Any named local objects named in *expr* are captured by reference so
lifetime management is important.

**NOTE!** Be very extra careful with lifetime issues when dealing with coroutines.

### **`LR_CO_THROW(`** *expr* **`)`**

Used in [expectations](#expectation) to throw an exception from a coroutine.
Note that when any [**`SIDE_EFFECT(...)`**](#SIDE_EFFECT) and
[**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT) are executed depends on the behaviour of the
coroutine promise type. This code may alter out-parameters.

`#include <trompeloeil/coro.hpp>`

Coroutines are supported if the compiler defines the
[**`__cpp_impl_coroutines`**](https://eel.is/c++draft/cpp.predefined#:__cpp_impl_coroutine)
feature test macro.

**NOTE!** Any named local objects named in *expr* are captured by reference so
lifetime management is important.

**NOTE!** Be very extra careful with lifetime issues when dealing with coroutines.

### **`LR_CO_YIELD(`** *expr* **`)`**

Used in [expectations](#expectation) with a coroutine type that can
[`co_yield`](https://en.cppreference.com/w/cpp/language/coroutines#co_yield).
You can add several **`LR_CO_YIELD`** to the same expectation, and the values will
be yielded one at the time, in the order they are listed. Note that
[**`CO_RETURN(`** *expr* **`)`**](#CO_RETURN) or
[**`LR_CO_RETURN(`** *expr* **`)`**](#LR_CO_RETURN) is still needed.

See also [**`CO_YIELD(`** *expr* **`]`**](#LR_CO_YIELD)

`#include <trompeloeil/coro.hpp>`

Coroutines are supported if the compiler defines the
[**`__cpp_impl_coroutines`**](https://eel.is/c++draft/cpp.predefined#:__cpp_impl_coroutine)
feature test macro.

**NOTE!** Any named local objects named in *expr* are captured by reference so
lifetime management is important.

**NOTE!** Be very extra careful with lifetime issues when dealing with coroutines.

### **`LR_RETURN(`** *expr* **`)`**

Used in [expectations](#expectation) to set the return value after having
evaluated every [**`SIDE_EFFECT(...)`**](#SIDE_EFFECT) and
[**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT).
For `void` functions **`LR_RETURN(...)`** is illegal. For non-`void` functions
exactly one of [**`RETURN(...)`**](#RETURN), **`LR_RETURN(...)`**,
[**`LR_THROW(...)`**](#LR_THROW) or [**`THROW(...)`**](#THROW) is required.
*expr* may refer to parameters in the call with their positional names `_1`,
`_2`, etc.
This code may alter out-parameters.

`#include <trompeloeil/mock.hpp>`

If you need to return an
[lvalue-reference](http://en.cppreference.com/w/cpp/language/reference),
to a variable, use
[`std::ref(value)`](http://en.cppreference.com/w/cpp/utility/functional/ref) or
[`std::cref(value)`](http://en.cppreference.com/w/cpp/utility/functional/cref)
for it, or just enclose the value in an extra parenthesis, like this
[**`.LR_RETURN((value))`**](reference.md/#RETURN).

**NOTE!** Any named local objects named in *expr* are captured by reference so
lifetime management is important.

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, int&(unsigned));
};

TEST(atest)
{
  C mock_obj;

  int rv = 3;
  ALLOW_CALL(mock_obj, func(0))
    .LR_RETURN(std::ref(rv)); // reference to captured local variable

  rv = 4;
  test_func(&mock_obj);
}
```

Above, the **`LR_RETURN(...)`** clause tells matching calls of
`mock_obj.func(...)` to return a reference to the local variable `rv`.
Since **`LR_RETURN(...)`** accesses local variables by reference, the value
of the returned reference will be 4 if called from within `test_func(...)`.

See also [**`RETURN(...)`**](#RETURN) which accesses copies of local variables.

### **`LR_SIDE_EFFECT(`** *expr* **`)`**

Used in [expectations](#expectation) to cause side effects for matching calls.
*expr* is only evaluated when all [**`WITH(...)`**](#WITH) and
[**`LR_WITH(...)`**](#LR_WITH) clauses are matched. *expr* may refer to
parameters in the call with their positional names `_1`, `_2`, etc. This code
may alter out-parameters. Several **`LR_SIDE_EFFECT(...)`** and
[**`SIDE_EFFECT(...)`**](#SIDE_EFFECT)
clauses can be added to a single [expectation](#expectation), and they are
evaluated in order.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(unsigned));
};

TEST(atest)
{
  C mock_obj;
  unsigned sum = 0;
  ALLOW_CALL(mock_obj, func(ANY(unsigned))
    .LR_SIDE_EFFECT(sum += _1);

  tested_func(&mock_obj);

  std::cout << "parameter sum=" << sum << "\n";
}
```

Above, `tested_func(&mock_obj)` is allowed to call `C::func(int)` any
number of times on `mock_obj`. Each time a side effect is that the local
variable `sum` gets the parameter value added to it. Since
**`LR_SIDE_EFFECT(...)`** refers to `sum` by reference, it is the actual
local variable that is changed is every call.

See also [**`SIDE_EFFECT(...)`**](#SIDE_EFFECT) which accesses copies of local
objects.

### **`LR_THROW(`** *expr* **`)`**

Used in [expectations](#expectation) to throw after having evaluated every
[**`SIDE_EFFECT(...)`**](#SIDE_EFFECT) and
[**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT) for a matching call.
*expr* may refer to parameters in the call with their positional names `_1`,
`_2`, etc. This code may alter out-parameters. It is not legal to combine
**`LR_THROW(...)`** with any of [**`THROW(...)`**](#THROW),
[**`LR_RETURN(...)`**](#LR_RETURN) or [**`RETURN(...)`**](#RETURN). Named local
objects are accessed by reference so lifetime management is important.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(unsigned));
};

TEST(atest)
{
  C mock_obj;
  const char* what="";

  ALLOW_CALL(mock_obj, func(3))
    .LR_THROW(std::invalid_argument(what));

  what = "nonsense";
  tested_func(&mock_obj);
}
```

Above, **`LR_THROW(std::invalid_argument(what))`** will refer to the C-string
`what` with the value it has at the time of a call to `mock_obj.func(3)`, i.e.
`"nonsense"` if `tested_func()` does the call.

See also [**`THROW(...)`**](#THROW) which accesses copies of local objects.

### **`LR_WITH(`** *expr* **`)`**

Used with [expectations](#expectation) to add further conditions for a
matching call. Typically used when [matchers](#matcher) are used for the
parameters, and often when the condition requires several parameter values
together.
*expr* can refer to parameters in the call with their positional names `_1`,
`_2`, etc. Even if the function signature has parameters as non-`const`
references, they are immutable in this context. Several **`LR_WITH(...)`**
and [**`WITH(...)`**](#WITH) clauses can be added to a single expectation and
they are tried in the order they are added until one has failed, or they all
have passed.

Named local objects are accessed by reference so lifetime management is
important.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(const char*));
};

using trompeloeil::_;

TEST(atest)
{
  C mock_obj;

  const char buff[] = "string";

  REQUIRE_CALL(mock_obj, func(_))
    .LR_WITH(_1 == buff);

  tested_func(buff, &mock_obj);
}
```

Above, **`LR_WITH(_1 == buff)`** checks the condition that the `const char*`
parameter is the same pointer value as the address to the local array `buff`.

**NOTE!** It is legal, but a *very* bad idea, to modify global/static objects in
**`LR_WITH(...)`**. If several [expectations](#expectation) could match and
are disambiguated by **`LR_WITH(...)`** and [**`WITH(...)`**](#WITH) the
global/static objects will be modified also by those
[expectations](#expectation) that do not match.

See also [**`WITH(...)`**](#WITH) which accesses copies of local objects.

### **`MAKE_CONST_MOCK(`** *func_name*, *signature* {, *specifiers* } **`)`**

Make a `const` [mock function](#mock_function) named *func_name*. It is a good
idea for this to implement a pure virtual function from an interface, but
it is not a requirement. `n` is the number of parameters in *signature*.
*specifiers* is an optional list which may include attributes or specifiers like
[`override`](http://en.cppreference.com/w/cpp/language/override) or
[`noexcept`](https://en.cppreference.com/w/cpp/language/noexcept_spec).

Because of limitations in how the preprocessor works,  *signature* **must** be written with
[trailing return type syntax](https://arne-mertz.de/2016/11/trailing-return-types-everywhere/).

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class I
{
public:
  virtual ~I() = default;
  virtual auto func1(int, const std::vector<int>&)) const -> int = 0;
};

class C
{
public:
  MAKE_CONST_MOCK(func1, auto (int, const std::vector<int>&) -> int, override);
  MAKE_CONST_MOCK(func2, auto (std::string) -> int);
};
```

Above, class `C` will effectively become:

```Cpp
class C : public I
{
public:
  auto func1(int, const std::vector<int>&) const -> int override;
  auto func2(std::string) const -> int;
};
```

It is not possible to mock operators, constructors or the destructor, but
you can call [mock functions](#mock_function) from those.

**Note!** The preprocessor is limited and can only handle nullary functions,
i.e. functions that do not accept any arguments, in some cases.

* MSVC handles nullary functions when compiling with `/Zc:preprocessor`
  with MSVC 19.40 (VS 17.10) or later.

* Gcc and Clang always handles nullary functions when compiling with
  C++20 or later, and when enabling a gcc extension by defining the macro 
  `TROMPELOEIL_HAS_GCC_PP` before `#include`:ing the trompeloeil headers, and
  compiling with `-std=gnu++11`, `-std=gnu++14` or `-std=gnu++17`.

Otherwise, use [**`MAKE_CONST_MOCK0(...)`**](#MAKE_CONST_MOCKn) to explicitly
define a nullary mock function.


See also [**`MAKE_MOCK(...)`**](#MAKE_MOCK) for non-`const`
member functions, and [**`MAKE_CONST_MOCKn(...)`**](#MAKE_CONST_MOCKn) for
explicit function arity.

### **`MAKE_CONST_MOCKn(`** *func_name*, *signature* {, *specifiers* } **`)`**

Make a `const` [mock function](#mock_function) named *func_name*. It is a good
idea for this to implement a pure virtual function from an interface, but
it is not a requirement. `n` is the number of parameters in *signature*.
*specifiers* is an optional list which may include attributes or specifiers like
[`override`](http://en.cppreference.com/w/cpp/language/override) or
[`noexcept`](https://en.cppreference.com/w/cpp/language/noexcept_spec).

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class I
{
public:
  virtual ~I() = default;
  virtual int func1(int, const std::vector<int>&)) const = 0;
};

class C
{
public:
  MAKE_CONST_MOCK2(func1, int(int, const std::vector<int>&), override);
  MAKE_CONST_MOCK1(func2, int(std::string));
};
```

Above, class `C` will effectively become:

```Cpp
class C : public I
{
public:
  int func1(int, const std::vector<int>&) const override;
  int func2(std::string) const;
};
```

It is not possible to mock operators, constructors or the destructor, but
you can call [mock functions](#mock_function) from those.

See also [**`MAKE_MOCKn(...)`**](#MAKE_MOCKn) for non-`const`
member functions and [**`MAKE_CONST_MOCK(...)`**`](#MAKE_CONST_MOCK) for
implicit function arity deduction.

### **`MAKE_MOCK(`** *func_name*, *signature* {, *specifiers* } **`)`**

Make a non-const [mock function](#mock_function) named *func_name*. It is a
good idea for this to implement a pure virtual function from an interface, but
it is not a requirement. `n` is the number of parameters in *signature*.
*specifiers* is an optional list which may include attributes or specifiers like
[`override`](http://en.cppreference.com/w/cpp/language/override) or
[`noexcept`](https://en.cppreference.com/w/cpp/language/noexcept_spec).

Because of limitations in how the preprocessor works,  *signature* **must** be written with
[trailing return type syntax](https://arne-mertz.de/2016/11/trailing-return-types-everywhere/).


`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class I
{
public:
  virtual ~I() = default;
  virtual auto func1(int, const std::vector<int>&)) -> int = 0;
};

class C : public I
{
public:
  MAKE_MOCK(func1, auto (int, const std::vector<int>&) -> int, override);
  MAKE_MOCK(func2, auto (std::string) -> int);
};
```

Above, class `C` will effectively become:

```Cpp
class C : public I
{
public:
  auto func1(int, const std::vector<int>&) -> int override;
  auto func2(std::string) -> int;
};
```

It is not possible to mock operators, constructors or the destructor, but
you can call [mock functions](#mock_function) from those.

**Note!** The preprocessor is limited and can only handle nullary functions,
i.e. functions that do not accept any arguments, in some cases.

* MSVC handles nullary functions when compiling with `/Zc:preprocessor`
  with MSVC 19.40 (VS 17.10) or later.

* Gcc and Clang always handles nullary functions when compiling with
  C++20 or later, and when enabling a gcc extension by defining the macro
  `TROMPELOEIL_HAS_GCC_PP` before `#include`:ing the trompeloeil headers, and
  compiling with `-std=gnu++11`, `-std=gnu++14` or `-std=gnu++17`.

Otherwise, use [**`MAKE_MOCK0(...)`**](#MAKE_MOCKn) to explicitly
define a nullary mock function.


See also [**`MAKE_CONST_MOCK(...)`**](#MAKE_CONST_MOCK) for `const`
member functions and [**`MAKE_MOCKn(...)`**](#MAKE_MOCKn) for explicit
function arity.

### **`MAKE_MOCKn(`** *func_name*, *signature* {, *specifiers* } **`)`**

Make a non-const [mock function](#mock_function) named *func_name*. It is a
good idea for this to implement a pure virtual function from an interface, but
it is not a requirement. `n` is the number of parameters in *signature*.
*specifiers* is an optional list which may include attributes or specifiers like
[`override`](http://en.cppreference.com/w/cpp/language/override) or
[`noexcept`](https://en.cppreference.com/w/cpp/language/noexcept_spec).

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class I
{
public:
  virtual ~I() = default;
  virtual int func1(int, const std::vector<int>&)) = 0;
};

class C : public I
{
public:
  MAKE_MOCK2(func1, int(int, const std::vector<int>&), override);
  MAKE_MOCK1(func2, int(std::string));
};
```

Above, class `C` will effectively become:

```Cpp
class C : public I
{
public:
  int func1(int, const std::vector<int>&) override;
  int func2(std::string);
};
```

It is not possible to mock operators, constructors or the destructor, but
you can call [mock functions](#mock_function) from those.

See also [**`MAKE_CONST_MOCKn(...)`**](#MAKE_CONST_MOCKn) for `const`
member functions and [**`MAKE_MOCK(...)`**`](#MAKE_MOCK) for implicit function
arity deduction.

### **`MAKE_STDMETHOD_MOCK(`** *func_name*, *signature* {, *specifiers* } **`)`**

Make a STDMETHODCALLTYPE [mock function](#mock_function) named *func_name*. It is a
good idea for this to implement a pure virtual function from an interface, but
it is not a requirement. `n` is the number of parameters in *signature*.
*specifiers* is an optional list which may include attributes or specifiers like
[`override`](http://en.cppreference.com/w/cpp/language/override) or
[`noexcept`](https://en.cppreference.com/w/cpp/language/noexcept_spec).

Because of limitations in how the preprocessor works,  *signature* **must** be written with
[trailing return type syntax](https://arne-mertz.de/2016/11/trailing-return-types-everywhere/).

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class I
{
public:
  virtual ~I() = default;
  virtual auto STDMETHODCALLTYPE func1(int, const std::vector<int>&)) -> int = 0;
};

class C : public I
{
public:
  MAKE_STDMETHOD_MOCK(func1, auto (int, const std::vector<int>&) -> int, override);
  MAKE_STDMETHOD_MOCK(func2, auto (std::string) -> int);
};
```

Above, class `C` will effectively become:

```Cpp
class C : public I
{
public:
  auto STDMETHODCALLTYPE func1(int, const std::vector<int>&) -> int override;
  auto STDMETHODCALLTYPE func2(std::string) -> int;
};
```

It is not possible to mock operators, constructors or the destructor, but
you can call [mock functions](#mock_function) from those.

**NOTE!** **`MAKE_STDMETHOD_MOCK(...)`** only works on Windows.

**NOTE!** The preprocessor is limited and can only handle nullary functions,
i.e. functions that do not accept any arguments, in some cases.

* MSVC handles nullary functions when compiling with `/Zc:preprocessor`
  with MSVC 19.40 (VS 17.10) or later.

* Gcc and Clang always handles nullary functions when compiling with
  C++20 or later, and when enabling a gcc extension by defining the macro
  `TROMPELOEIL_HAS_GCC_PP` before `#include`:ing the trompeloeil headers, and
  compiling with `-std=gnu++11`, `-std=gnu++14` or `-std=gnu++17`.

Otherwise, use [**`MAKE_STDMETHOD_MOCK0(...)`**](#MAKE_STDMETHOD_MOCKn) to
explicitly define a nullary mock function.

See also [**`MAKE_STDTMETHOD_MOCKn(...)`**](#MAKE_STDMETHOD_MOCKn) for explicit
function arity.

### **`MAKE_STDMETHOD_MOCKn(`** *func_name*, *signature* {, *specifiers* } **`)`**

Make a STDMETHODCALLTYPE [mock function](#mock_function) named *func_name*. It is a
good idea for this to implement a pure virtual function from an interface, but
it is not a requirement. `n` is the number of parameters in *signature*.
*specifiers* is an optional list which may include attributes or specifiers like
[`override`](http://en.cppreference.com/w/cpp/language/override) or
[`noexcept`](https://en.cppreference.com/w/cpp/language/noexcept_spec).

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class I
{
public:
  virtual ~I() = default;
  virtual int STDMETHODCALLTYPE func1(int, const std::vector<int>&)) = 0;
};

class C : public I
{
public:
  MAKE_STDMETHOD_MOCK2(func1, int(int, const std::vector<int>&), override);
  MAKE_STDMETHOD_MOCK1(func2, int(std::string));
};
```

Above, class `C` will effectively become:

```Cpp
class C : public I
{
public:
  int STDMETHODCALLTYPE func1(int, const std::vector<int>&) override;
  int STDMETHODCALLTYPE func2(std::string);
};
```

It is not possible to mock operators, constructors or the destructor, but
you can call [mock functions](#mock_function) from those.

**NOTE!** **`MAKE_STDMETHOD_MOCKn(...)`** only works on Windows.

See also [**`MAKE_STDMETHOD_MOCK(...)`**`](#MAKE_STDMETHOD_MOCK) for implicit
function arity deduction.

### **`NAMED_ALLOW_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**

Make a [`std::unique_ptr<trompeloeil::expectation>`](#expectation_type)
allowing *mock_object*.*func_name*(*parameter_list*) to be
called zero or more times until the expectation object is destroyed.
*parameter_list* may contain exact values or [matchers](#matcher)
that describes matching calls.

This is the same as
[**`NAMED_REQUIRE_CALL(...)`**](#NAMED_REQUIRE_CALL).[**`TIMES(`**](#TIMES) 0,infinity **`)`**.

Matches any number of times, but is not required to match. (_Actually the limit is
0..~0ULL, but that is for all practical purposes "infinity"_.)

**NOTE!** Any named objects referenced in attached
[**`LR_WITH(...)`**](#LR_WITH), [**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT),
[**`LR_RETURN(...)`**](#LR_RETURN) and [**`LR_THROW(...)`**](#LR_THROW) are
captured by reference so lifetime management is important.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
};

using trompeloeil::gt;
using trompeloeil::lt;
using expectation = std::unique_ptr<trompeloeil::expectation>;

TEST(atest)
{
  C mock_obj;

  expectation x1 = NAMED_ALLOW_CALL(mock_obj, func(gt(0));

  test_function(0, &mock_obj);

  expectation x2 = NAMED_ALLOW_CALL(mock_obj, func(lt(0));

  test_function(1, &mock_obj);

  x1.reset(); // no longer allow calls with positive values

  test_function(2, &mock_obj);
}
```

Above each **`NAMED_ALLOW_CALL(mock_obj, func(...))`** creates an expectation
that *mock_obj.func()* may be called any number of times. Each expectation is
valid for the lifetime of the expectation object. In the example above,
this means that `x1` is valid for the first two calls to `test_function(...)`,
while `x2` is valid for the last two calls to `test_function(...)`.

See also [**`ALLOW_CALL(...)`**](#ALLOW_CALL) which creates an expectation
that is valid until the end of the surrounding scope.

### **`NAMED_FORBID_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**

Make a [`std::unique_ptr<trompeloeil::expectation>`](#expectation_type)
disallowing calls to *mock_object*.*func_name*(*parameter_list*) until the
expectation object is destroyed. *parameter_list* may contain exact values or
[matchers](#matcher) that describes matching calls.

This is the same as
[**`NAMED_REQUIRE_CALL(...)`**](#NAMED_REQUIRE_CALL).[**`TIMES(`**](#TIMES)
0 **`)`**, making any matching call an error. This is typically done when a wider
scope would allow the call. [**`RETURN(...)`**](#RETURN),
[**`LR_RETURN(...)`**](#LR_RETURN), [**`LR_THROW(...)`**](#LR_THROW) and
[**`THROW(...)`**](#THROW) are illegal in a **`NAMED_FORBID_CALL(...)`**.

**NOTE!** Any named objects referenced in attached
[**`LR_WITH(...)`**](#LR_WITH) are captured by reference so lifetime management
is important.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
}

using trompeloeil::_;
using trompeloeil::gt;
using trompeloeil::lt;

using expectation = std::unique_ptr<trompeloeil::expectation>;

TEST(atest)
{
  C mock_obj;

  ALLOW_CALL(mock_obj, func(_));

  expectation x1 = NAMED_FORBID_CALL(mock_obj, func(gt(0));

  test_function(0, &mock_obj);

  expectation x2 = NAMED_FORBID_CALL(mock_obj, func(lt(0));

  test_function(1, &mock_obj);

  x1.reset(); // allow calls with positive values again

  test_function(2, &mock_obj);
}
```

Above, calls to `mock_obj.func()` are generally allowed throughout the test.
However, `x1` imposes a restriction that calls with positive values are illegal,
and that restriction is in place for the first two calls to
`test_function(...)`. `x2` imposes a restrictions that calls with negative
values are illegal, and that restriction is in place for the last two calls to
`test_function(...)`.

See also [**`FORBID_CALL(...)`**](#FORBID_CALL) which creates an
[expectation](#expectation) that is valid until the end of the surrounding scope.

### **`NAMED_REQUIRE_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**

Make a [`std::unique_ptr<trompeloeil::expectation>`](#expectation_type)
requiring that *mock_obj*.*func_name*(*parameter_list*) is called exactly once
before the expectation object is destroyed. *parameter_list* may contain exact
values or [matchers](#matcher) that describes matching calls.

The number of matches required before the [expectation](#expectation) object
is destroyed can be changed with an optional [**`TIMES(...)`**](#TIMES) clause.

**NOTE!** Any named objects referenced in attached
[**`LR_WITH(...)`**](#LR_WITH), [**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT),
[**`LR_RETURN(...)`**](#LR_RETURN) and [**`LR_THROW(...)`**](#LR_THROW) are
captured by reference so lifetime management is important.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
}

using trompeloeil::gt;
using trompeloeil::lt;

using expectation = std::unique_ptr<trompeloeil::expectation>;

TEST(atest)
{
  C mock_obj;

  expectation x1 = NAMED_REQUIRE_CALL(mock_obj, func(gt(0));

  test_function(0, &mock_obj);

  expectation x2 = NAMED_REQUIRE_CALL(mock_obj, func(lt(0));

  test_function(1, &mock_obj);

  x1.reset(); // The call with positive number must be done here.

  test_function(2, &mock_obj);
}
```

Above, the first two calls to `test_function(...)` must together call
`mock_obj.func(...)` exactly once with a positive value, and the last two
calls to `test_function(...)` must together call `mock_obj.func(...)`
exactly once with a negative number.

See also [**`REQUIRE_CALL(...)`**](#REQUIRE_CALL) which creates an
[expectation](#expectation) that is valid until the end of the surrounding scope.

### **`NAMED_REQUIRE_DESTRUCTION(`** *mock_object* **`)`**

Create a
[`std::unique_ptr<trompeloeil::expectation>`](#expectation_type)
object which reports a violation if the
[**`deathwatched_type`**](#deathwatched_type) [mock object](#mock_object) is
not destroyed by the time the `expectation` is destroyed.

`#include <trompeloeil/lifetime.hpp>`

Example:

```Cpp
class C
{
public:
  virtual ~C() = default; // must be virtual for deathwatched
  MAKE_MOCK1(func, void(int));
}

using monitor = std::unique_ptr<trompeloeil::expectation>;
using trompeloeil::deathwatched;

TEST(atest)
{
  C* p = new deathwatched<C>();

  test_function(0, p); // must not destroy *p

  monitor m = NAMED_REQUIRE_DESTRUCTION(*p);

  test_function(1, p);

  m.reset(); // *p must have been destroyed here
}
```

Above, `p` points to a [`deathwatched`](#deathwatched_type)
[mock object](#mock_object), meaning that a violation is reported if `*p` is
destroyed without having a destruction requirement.

The monitor `m` is a requirement that `*p` is destroyed before the
[`lifetime_monitor`](#lifetime_monitor_type)
(subtype of [`expectation`](#expectation_type)) held by `m` is destroyed.

It is thus a violation if the first call to `test_function(...)` destroys
`*p`, and another violation if the second call to `test_function(...)`
does not destroy `*p`

See also [**`REQUIRE_DESTRUCTION(...)`**](#REQUIRE_DESTRUCTION) which places
a requirement that the [`deathwatched`](#deathwatched_type)
[mock object](#mock_object) is destroyed before the end of the scope.

### **`REQUIRE_CALL(`** *mock_object*, *func_name*(*parameter_list*)**`)`**

Make an [expectation](#expectation) requiring that
*mock_obj*.*func_name*(*parameter_list*) is called exactly once before
the end of the scope. *parameter_list* may contain exact values
or [matchers](#matcher) that describes matching parameter values for the
[expectation](#expectation).

The number of matches required before the [expectation](#expectation) object
is destroyed can be changed with an optional [**`TIMES(...)`**](#TIMES) clause.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(int));
}

using trompeloeil::gt;
using trompeloeil::lt;

TEST(atest)
{
  C mock_obj;
  {
    REQUIRE_CALL(mock_obj, func(gt(0));

    test_function(0, &mock_obj);
    // end of scope, requirement must be fulfilled here
  }
  {
    REQUIRE_CALL(mock_obj, func(lt(0));

    test_function(1, &mock_obj);
    // end of scope, requirement must be fulfilled here
  }
}
```

Above, the first call to `test_function(...)` must call
`mock_obj.func(...)` exactly once with a positive value, and the second
call to `test_function(...)` must call `mock_obj.func(...)`
exactly once with a negative number.

See also [**`NAMED_REQUIRE_CALL(...)`**](#NAMED_REQUIRE_CALL) which creates an
[expectation](#expectation) that is held by a
[`std::unique_ptr<trompeloeil::expectation>`](#expectation_type) which can be stored in test
fixtures.

### **`REQUIRE_DESTRUCTION(`** *mock_object* **`)`**

Create an anonymous [`lifetime_monitor`](#lifetime_monitor_type) which reports
a violation if the [**`deathwatched`**](#deathwatched_type)
[mock object](#mock_object) is not destroyed by the end of the scope.

`#include <trompeloeil/lifetime.hpp>`

Example:

```Cpp
class C
{
public:
  virtual ~C() = default; // must be virtual for deathwatched
  MAKE_MOCK1(func, void(int));
}

using trompeloeil::deathwatched;

TEST(atest)
{
  C* p = new deathwatched<C>();

  test_function(0, p); // must not destroy *p

  {
    REQUIRE_DESTRUCTION(*p);

    test_function(1, p);
    // end of scope, *p must have been destroyed here
  }
}
```

Above, `p` points to a [`deathwatched`](#deathwatched_type)
[mock object](#mock_object), meaning that a violation is reported if `*p` is
destroyed without having a destruction requirement.

**`REQUIRE_DESTRUCTION(...)`** in the local scope puts a requirement on
`*p` that it must be destroyed by the end of the scope.

It is thus a violation if the first call to `test_function(...)` destroys
`*p`, and another violation if the second call to `test_function(...)`
does not destroy `*p`.

See also [**`NAMED_REQUIRE_DESTRUCTION(...)`**](#NAMED_REQUIRE_DESTRUCTION)
which creates the requirement that the [`deathwatched`](#deathwatched_type)
[mock object](#mock_object) is destroyed as a
[`std::unique_ptr<trompeloeil::lifetime_monitor>`](#lifetime_monitor_type)
which can be stored in test fixtures.

### **`RETURN(`** *expr* **`)`**

Used in [expectations](#expectation) to set the return value after having
evaluated every [**`SIDE_EFFECT(...)`**](#SIDE_EFFECT) and
[**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT).
For `void` functions **`RETURN(...)`** is illegal. For non-`void` functions
exactly one of [**`LR_RETURN(...)`**](#LR_RETURN), **`RETURN(...)`**,
[**`LR_THROW(...)`**](#LR_THROW) or [**`THROW(...)`**](#THROW) is required.
*expr* may refer to parameters in the call with their positional names `_1`,
`_2`, etc.
This code may alter out-parameters.

Named local objects accessed here refers to a immutable copies.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, int&(unsigned));
};

using trompeloeil::_;

std::vector<int> values{3,2,1,0};

TEST(atest)
{
  C mock_obj;

  int offset = 1;
  ALLOW_CALL(mock_obj, func(_))
    .WITH(_1 + offset < values.size())
    .RETURN(values[_1 + offset]);

  offset = 2;
  test_func(&mock_obj);
}
```

Above, the **`RETURN(...)`** clause tells matching calls of
`mock_obj.func(...)` to return a reference to an element in the global
`std::vector<int> values`. Since **`RETURN(...)`** accesses copies of local
variables, the value of `offset` is 1 in the index calculation if called from
within `test_func(...)`.

**NOTE!** It is illegal to return a reference to a captured local variable.

See also [**`LR_RETURN(...)`**](#LR_RETURN) which accesses local variables
by reference.

### **`SIDE_EFFECT(`** *expr* **`)`**

Used in [expectations](#expectation) to cause side effects for matching calls.
*expr* is only evaluated when all [**`WITH(...)`**](#WITH) and
[**`LR_WITH(...)`**](#LR_WITH) clauses are matched. *expr* may refer to
parameters in the call with their positional names `_1`, `_2`, etc. This code
may alter out-parameters.
Several **`SIDE_EFFECT(...)`** and [**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT)
clauses can be added to a single [expectation](#expectation), and they are
evaluated in order.

Named local objects accessed here refers to immutable copies.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(unsigned));
};

unsigned sum = 0;

TEST(atest)
{
  C mock_obj;
  unsigned offset = 0;
  ALLOW_CALL(mock_obj, func(ANY(unsigned))
    .SIDE_EFFECT(sum += offset + _1);

  offset = 2;
  tested_func(&mock_obj);

  std::cout << "offset corrected parameter sum=" << sum << "\n";
}
```

Above, `tested_func(...)` is allowed to call `mock_obj.func()` any
number of times. Each time a side effect is that the global
variable `sum` gets the parameter value added to it adjusted for `offset`.
Since **`SIDE_EFFECT(...)`** refers to a copy of `offset`, the value of
`offset` is `0` in any matching calls from within `tested_func(...)`

See also [**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT) which accesses local
objects by reference.

### **`THROW(`** *expr* **`)`**

Used in [expectations](#expectation) to throw after having evaluated every
[**`SIDE_EFFECT(...)`**](#SIDE_EFFECT) and
[**`LR_SIDE_EFFECT(...)`**](#LR_SIDE_EFFECT) for a matching call.
*expr* may refer to parameters in the call with their positional names `_1`,
`_2`, etc. This code may alter out-parameters. It is not legal to combine
**`THROW(...)`** with any of [**`LR_THROW(...)`**](#LR_THROW),
[**`LR_RETURN(...)`**](#LR_RETURN) or [**`RETURN(...)`**](#RETURN).

Named local objects here refers to immutable copies.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(unsigned));
};

TEST(atest)
{
  C mock_obj;
  std::string what="<unknown>";

  ALLOW_CALL(mock_obj, func(3))
    .THROW(std::invalid_argument(what));

  what = "";
  tested_func(&mock_obj);
}
```

Above, **`THROW(...)`** will refer to a copy of the string `what` with the value
`"<unknown>"` if a matching call is made from within `tested_func(...)`

See also [**`LR_THROW(...)`**](#LR_THROW) which accesses copies of local objects.

### **`TIMES(`** *limits* **`)`** and **`RT_TIMES(`** *limits* **`)`**

Used in [**`REQUIRE_CALL(...)`**](#REQUIRE_CALL) and
[**`NAMED_REQUIRE_CALL(...)`**](#NAMED_REQUIRE_CALL) to set the limits on
the number of matching calls required.

*limits* may be a single number, in which case it is the exact number of
matching calls required.

*limits* may also be two numbers, describing a range *min-inclusive*,
*max-inclusive*.

If the minimum number of matching calls is not met before the end of the
lifetime of the [expectation](#expectation), a violation is reported.

If the maximum number of matching calls is exceeded, a violation is reported.

The difference between **`TIMES(...)`** and **`RT_TIMES(...)`** is, that the
prior only supports [`constexpr`](http://en.cppreference.com/w/cpp/language/constexpr)
arguments, while the latter is designed to accept also runtime arguements.
If invalid bounds are provided, **`TIMES(...)`** issues a compile-error.
**`RT_TIMES(...)`** will compile successfully, but will raise a ``std::logic_error``
during construction.

Either a single **`TIMES(...)`** or **`RT_TIMES(...)`** may be used for each
[**`REQUIRE_CALL(..)`**](#REQUIRE_CALL) or
[**`NAMED_REQUIRE_CALL(...)`**](#NAMED_REQUIRE_CALL).

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(unsigned));
};

using trompeloeil::_;

TEST(atest)
{
  C mock_obj;

  REQUIRE_CALL(mock_obj, func(_))
    .TIMES(2, 5);

  tested_func(&mock_obj);
```

Above, `tested_func(...)` is expected to call `mock_obj.func()` at least two
times, and no more than 5 times.

See also the helpers [**`AT_LEAST(...)`**](#AT_LEAST) and
[**`AT_MOST(...)`**](#AT_MOST).

See also [**`IN_SEQUENCE(...)`**](#IN_SEQUENCE) for information about how
`.TIMES(...)` and `.RT_TIMES(...)` work together with [**`sequence`**](#sequence_type)
objects.

### **`WITH(`** *expr* **`)`**

Used with [expectations](#expectation) to add further conditions for a
matching call. Typically used when [matchers](#matcher) are used for the
parameters, and often when the condition requires several parameter values
together.
*expr* can refer to parameters in the call with their positional names `_1`,
`_2`, etc. Even if the function signature has parameters as non-`const`
references, they are immutable in this context. Several **`WITH(...)`**
and [**`LR_WITH(...)`**](#LR_WITH) clauses can be added to a single expectation
and they are tried in the order until one has failed, or they all have passed.

Named local objects here refers to immutable copies.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class C
{
public:
  MAKE_MOCK1(func, void(const char*, size_t));
};

using trompeloeil::_;

TEST(atest)
{
  C mock_obj;

  std::string str = "string";

  REQUIRE_CALL(mock_obj, func(_,_))
    .WITH(std::string(_1, _2) == str);

  str = ""; // does not alter the copy in the expectation above.

  tested_func(buff, &mock_obj);
}
```

Above, **`WITH(std::string(_1, _2) == str)`** checks the condition that the
string constructed from the parameters is equal to a copy of the local variable
`str`. To pass the test, `tested_func(...)` must in other words call
`mock_obj.func()` with string `"string"`.

**NOTE!** It is legal, but a *very* bad idea, to modify global/static objects in
**`WITH(...)`**. If several [expectations](#expectation) could match and
are disambiguated by [**`LR_WITH(...)`**](#LR_WITH) and **`WITH(...)`** the
global/static objects will be modified also by those
[expectations](#expectation) that do not match.

See also [**`LR_WITH(...)`**](#LR_WITH) which accesses local objects by
reference.

## Types and Templates (alphabetical order)

### `trompeloeil::deathwatched<T>`

Template used when it is necessary to control the life time of a
[mock object](#mock_object). The macros
[**`REQUIRE_DESTRUCTION(...)`**](#REQUIRE_DESTRUCTION) and
[**`NAMED_REQUIRE_DESTRUCTION(...)`**](#NAMED_REQUIRE_DESTRUCTION)
operates on instances of `trompeloeil::deathwatched<T>`.

`#include <trompeloeil/lifetime.hpp>`

Example:

```Cpp
class Mock
{
public:
  virtual ~Mock() = default; // virtual destructor needed for deathwatched<>
  MAKE_MOCK1(func, void(int));
};

using trompeloeil::_;

void test_func()
{
  auto p = new trompeloeil::deathwatched<Mock>();
  ALLOW_CALL(*p, func(_));
  func1(p);
  {
    FORBID_CALL(*p, func(_));
    REQUIRE_DESTRUCTION(*p);
    func2(p);
  }
}
```

Above, `func1(p)` must not destroy `p`, or a violation is reported, and
`func2(p)` may not call the [mock function](#mock_function) on `p`, but
is required to destroy the [mock object](#mock_object), or a violation will
be reported.

`trompeloeil::deathwatched<T>` inherits from `T`, and the constructor
accepts any parameters and
[perfectly forwards](http://www.cppsamples.com/common-tasks/perfect-forwarding.html)
them to the constructor of `T`. The mock type `T` must have a virtual
destructor.

### `trompeloeil::expectation`

Base class for all [expectations](#expectation). The macros
[**`NAMED_ALLOW_CALL(...)`**](#NAMED_ALLOW_CALL),
[**`NAMED_FORBID_CALL(...)`**](#NAMED_FORBID_CALL) and
[**`NAMED_REQUIRE_CALL(...)`**](#NAMED_REQUIRE_CALL) results in a
[`std::unique_ptr<trompeloeil::expectation>`](http://en.cppreference.com/w/cpp/memory/unique_ptr)
which you can hold in a variable.

`#include <trompeloeil/mock.hpp>`

### `trompeloeil::expectation_violation`

The exception type used by default to report violations.

```Cpp
class expectation_violation : public std::logic_error
{
public:
  using std::logic_error::logic_error;
};
```

The `what()` string contains the violation report message.

`#include <trompeloeil/mock.hpp>`

### `trompeloeil::lifetime_monitor`

The macro [**`NAMED_REQUIRE_DESTRUCTION(...)`**](#NAMED_REQUIRE_DESTRUCTION)
results in a
[`std::unique_ptr<trompeloeil::lifetime_monitor>`](http://en.cppreference.com/w/cpp/memory/unique_ptr)
which you can hold in a variable. `trompeloeil::lifetime_monitor` inherits from
[`trompeloeil::expectation`](#expectation_type).

`#include <trompeloeil/lifetime.hpp>`

Example:

```Cpp
class Mock
{
public:
  virtual ~Mock() = default; // virtual destructor needed for deathwatched<>
  MAKE_MOCK1(func, void(int));
};

using trompeloeil::_;
using monitor = std::unique_ptr<trompeloeil::lifetime_monitor>;

void test_func()
{
  auto p = new trompeloeil::deathwatched<Mock>();
  ALLOW_CALL(*p, func(_));
  func1(p);
  {
    FORBID_CALL(*p, func(_));
    monitor m = NAMED_REQUIRE_DESTRUCTION(*p);
    std::unique_ptr<trompeloeil::expectation> e = std::move(m);
    func2(p);
    e.reset();
  }
}
```

### `trompeloeil::matcher`

`trompeloeil::matcher` is the base class for all [matchers](#matcher). It does
not do anything and is solely used in internal
[`SFINAE`](http://en.cppreference.com/w/cpp/language/sfinae) constructions
and [tag dispatch](http://www.generic-programming.org/languages/cpp/techniques.php#tag_dispatching)

Use it, or [`trompeloeil::typed_matcher<T>`](#typed_matcher), as the base class
when writing custom [matchers](CookBook.md/#custom_matchers).

`#include <trompeloeil/mock.hpp>`

### `trompeloeil::mock_interface<T>`

`trompeloeil::mock_interface<T>` is a template useful when creating a mock from
an existing interface (i.e. a `struct` or `class` with virtual functions that
you want to mock).

It enables use of the [**`IMPLEMENT_MOCKn(...)`**](#IMPLEMENT_MOCKn) and
[**`IMPLEMENT_CONST_MOCKn(...)`**](#IMPLEMENT_CONST_MOCKn) macros.
The [**`MAKE_MOCK(...)`**](#MAKE_MOCK), [**`MAKE_MOCKn(...)`**](#MAKE_MOCKn),
[**`MAKE_CONST_MOCK(...)`**](#MAKE_CONST_MOCK) and
[**`MAKE_CONST_MOCKn(...)`**](#MAKE_CONST_MOCKn) macros can also be used.

The interface type `T` must not be final.

`#include <trompeloeil/mock.hpp>`

Example:

```Cpp
class interface
{
public:
  virtual ~interface() = default;
  virtual void func(int) = 0;
};

class mock : trompeloeil::mock_interface<interface>
{
public:
  IMPLEMENT_MOCK1(func); // implements pure virtual interface::func(int);
};

void tested_func(interface& i);

void test()
{
  mock m;
  REQUIRE_CALL(m, func(3));
  tested_func(m);
}
```

**NOTE!** `mock_interface<T>` cannot be used to inherit multiple interfaces.

### `trompeloeil::ok_reporter_func`

A type used to pass information to the unit testing frame work that a call to a
[mock function](#mock_function) has not been reported as a violation.

```Cpp
using trompeloeil::ok_reporter_func = std::function<const char*>;
```

`#include <trompeloeil/mock.hpp>`

The string passed is the parameters to the expectation. E.g.

```Cpp
struct Mock
{
  MAKE_MOCK1(func, void(int));
};

TEST(...)
{
  Mock m;
  REQUIRE_CALL(m, func(3)); // passes "m.func(3)" to OK reporter

  ...
}
```

###  `trompeloeil::printer<T>`

`printer<T>` is a type that formats values to strings in reports from *Trompeloeil*.

```Cpp
template <typename T, typename = void>
struct printer
{
  static void print(ostream& os, const T& t);
};
```

By default the `print` function formats using `os << t`, provided the type `T`
can be inserted into an `ostream`, otherwise it gives a hex-dump of the bytes
occupied by the object.

The type `trompeloeil::printer<T>` is a customization point that you can use
to define string formatting for types that do not support `os << t`, or for
which you  want a different representation in reports from *Trompeloeil*. The
second template parameter, which must be `void` if present, is a chance to add
SFINAE constraints on the T.
See example in the [Cook Book](CookBook.md/#custom_formatting).

`#include <trompeloeil/mock.hpp>`

### `trompeloeil::reporter_func`

A type used to pass information to the unit testing frame work that a call has
been made in violation of a [mock function](#mock_function).

```Cpp
using trompeloeil::reporter_func = std::function<void(trompeloeil::severity,
                                                      char const *file,
                                                      unsigned long line,
                                                      const std::string& msg)>;
```

See [`trompeloeil::severity`](#severity_type).

The parameter `msg` contains detailed information about the violation and
which (if any) [expectations](#expectation) there are on the
[mock function](#mock_function).

`#include <trompeloeil/mock.hpp>`

### `trompeloeil::sequence`

Type of object used for fine-tuned control of sequencing of matched
[expectations](#expectation).

`#include <trompeloeil/sequence.hpp>`

Example:

```Cpp
class FileOps
{
public:
  using handle = int;
  MAKE_MOCK1(open, handle(const std::string&));
  MAKE_MOCK3(write, size_t(handle, const char*, size_t));
  MAKE_MOCK1(close, void(handle));
};

using trompeloeil::ne;

void test()
{
  FileOps ops;

  auto seq = trompeloeil::sequence; // sequence object

  int handle = 4711;

  REQUIRE_CALL(ops, open("name"))
    .RETURN(handle)
    .IN_SEQUENCE(seq);

  REQUIRE_CALL(ops, write(handle, ne(nullptr), ne(0)))
    .RETURN(0)                                         // indicate failure
    .IN_SEQUENCE(seq);

  REQUIRE_CALL(ops, write(handle, ne(nullptr), ne(0)))
    .RETURN(_3)                                        // successful retry
    .IN_SEQUENCE(seq);

  REQUIRE_CALL(ops, close(handle))
    .IN_SEQUENCE(seq);

  test_writes(&ops);
}
```

Sequence objects are movable but not copyable.

**NOTE!** The [**`.IN_SEQUENCE(...)`**](#IN_SEQUENCE) macro accepts many
sequence objects.

###  `trompeloeil::severity`

Type used in violation reports to dictate what actions are allowed by the
report handler.

```Cpp
namespace trompeloeil {
  enum class severity { fatal, nonfatal };
}
```

A value of `trompeloeil::severity::fatal` dictates that the report handler
must not return. It may throw or end the program execution.

A value of `trompeloeil::severity::nonfatal` dictates that the report handler
is called from stack rollback and must not throw, lest
[`std::terminate`](http://en.cppreference.com/w/cpp/error/terminate) is
called.

`#include <trompeloeil/mock.hpp>`

### `trompeloeil::stream_tracer`

An instance of `trompeloeil::stream_tracer` prints information about
matched calls to the
[output stream](http://en.cppreference.com/w/cpp/io/basic_ostream)
it refers to. `stream_tracer` inherits from
[`trompeloeil::tracer`](#tracer_type).

`#include <trompeloeil/stream_tracer.hpp>`

```Cpp
namespace trompeloeil {
class stream_tracer : public ::trompeloeil::tracer
{
public:
  stream_tracer(std::ostream& stream);
  void trace(char const* file, unsigned long line, std::string const& call) override;
};
}
```

See "[Using `trompeloeil::stream_tracer`](CookBook.md/#stream_tracer)" in the
[Cook Book](CookBook.md).

### `trompeloeil::tracer`

Base class for tracers. Inherit from it when writing custom tracers.

`#include <trompeloeil/stream_tracer.hpp>`

```Cpp
namespace trompeloeil {
class tracer
{
public:
  virtual void trace(char const* file, unsigned long line, std::string const& call) = 0;
protected:
   tracer();
   tracer(tracer const&) = delete;
   virtual ~tracer();
   ...
};
}
```

See "[Writing custom tracers](CookBook.md/#custom_tracer)" in the
[Cook Book](CookBook.md) for an example.

###  `trompeloeil::typed_matcher<T>`

Convenience class available when writing custom matchers for a specific
type. It inherits from [`trompeloeil::matcher`](#matcher_type).

See "[Writing custom matchers](CookBook.md/#custom_matchers)" in the
[Cook Book](CookBook.md) for examples.

`#include <trompeloeil/matcher.hpp>`

## Functions

###  `trompeloeil::expectation::is_satisfied() const`

Query an [expectation object](#expectation_type) if it is satisfied, i.e. if
it will not report a missing call if it is destroyed. If
[**`.TIMES()`**](#TIMES) is used, this is true if the minimum number of calls
has been reached.

`#include <trompeloeil/mock.hpp>`

```Cpp
test(...)
{
  ...
  auto e = NAMED_REQUIRE_CALL(mock_obj, func())
             .TIMES(2,5);
  assert(!e->is_satisfied()); // no calls made yet.
  mock_obj.func();
  assert(!e->is_satisfied()); // Only one call made, min is 2.
  mock_obj.func();
  assert(e->is_satisfied()); // now 2 calls are made, so it's satisfied
  mock_obj.func();
  assert(e->is_satisfied()); // 3 calls are made, it's still satisfied
}
```

###  `trompeloeil::expectation::is_saturated() const`

Query an [expectation object](#expectation_type) if it is saturated, i.e. if
another call will report an unexpected call. If [**`.TIMES()`**](#TIMES) is
used, this is true if the maximum number of calls has been reached.

`#include <trompeloeil/mock.hpp>`

```Cpp
  ...
  auto e = NAMED_REQUIRE_CALL(mock_obj, func())
             .TIMES(2,4);
  assert(!e->is_saturated()); // no calls made yet.
  mock_obj.func();
  assert(!e->is_saturated()); // Only one call made, max is 4.
  mock_obj.func();
  assert(!e->is_saturated()); // now 2 calls are made, still not saturated
  mock_obj.func();
  assert(!e->is_saturated()); // 3 calls, one more to go.
  mock_obj.func();
  assert(e->is_saturated());  // 4 calls, the expectation is now saturated

  /* mock_obj.func();*/ // would cause "unexpected call" error.
```

###  `trompeloeil::get_lock()`

Get the global
[`recursive_mutex`](http://en.cppreference.com/w/cpp/thread/recursive_mutex)
used by *Trompeloeil*. The mutex is held until the end of the scope.

`#include <trompeloeil/mock.hpp>`

### `trompeloeil::print(std::ostream& os, T const& t)`

By default `print()` uses the type [`printer<T>`](#printer) to format
data to strings.

You can write specializations of
`trompeloeil::print(std::ostream& os, T const& t)` for your own types
`T`, but it is preferable to write a specialization of the type
[`printer<T>`](#printer) instead, which also works for partial
specializations.  See example in the
[Cook Book](CookBook.md/#custom_formatting).

`#include <trompeloeil/mock.hpp>`

### `trompeloeil::is_null(T const&)`

Null check that works for all types. If `T` is not comparable with
`nullptr` the value is false. This is mostly used when writing
[duck typed matchers](CookBook.md/#custom_matchers).

`#include <trompeloeil/mock.hpp>`

### `trompeloeil::make_matcher<Type>(...)`

```Cpp
template <typename Type, typename Predicate, typename Printer, typename ... T>
auto make_matcher(Predicate predicate /* bool (Type& value, T const& ...) */,
                  Printer printer     /* void (std::ostream&, T const& ...) */,
                  T&& ... stored_values);
```

If `Type` is `trompeloeil::wildcard` a
[duck typed matcher](CookBook.md/#duck_typed_matcher) is created, otherwise
a matcher for the specified type `Type` is created.

`T&&...` is any number of values you want stored in the matcher.

`predicate` is a callable object, typically a lambda, that accepts the
value to check for, and each of the stored values `T&&...` in order as
`const&`. When `Type` is `trompeloeil::wildcard`, the first parameter must
 be of `auto` type.  The return value must be convertible to `bool`.

`printer` is a callable object, typically a lambda, that accepts an
[`ostream&`](http://en.cppreference.com/w/cpp/io/basic_ostream) and the
stored values `T&&...` in order as `const&`.

Examples are found in the Cook Book under
[Writing custom matchers](CookBook.md/#custom_matchers)

`#include <trompeloeil/matcher.hpp>`

### `trompeloeil::set_reporter(...)`

These functions are used to adapt *Trompeloeil* to your unit test framework
of choice.

The default reporter throws
[`trompeloeil::expectation_violation`](#expectation_violation_type) for
all reports, with the violation message in the `what()` string.

If this is not suitable, you can change the report mechanism by
calling `trompeloeil::set_reporter(...)`

`#include <trompeloeil/mock.hpp>`

```Cpp
reporter_func
trompeloeil::set_reporter(std::function<void(trompeloeil::severity,
                                             char const *file,
                                             unsigned long line,
                                             const std::string& msg)>)
```

The return value is the previous reporter function.

```Cpp
std::pair<reporter_func, ok_reporter_func>
trompeloeil::set_reporter(std::function<void(trompeloeil::severity,
                                             char const *file,
                                             unsigned long line,
                                             const std::string& msg)> reporter,
                          std::function<void(char const* msg> ok_reporter)
)
```

The return value is the previous `reporter` and `ok_reporter`. An `ok_reporter`
is called for every call to a [mock function](#mock_function) that is not
reported as a violation. By default OK reports are ignored.

See [`trompeloeil::severity`](#severity_type) for the rules that it
dictates.

See [`trompeloeil::reporter_func`](#reporter_func) and
[`trompeloeil::ok_reporter_func`](#ok_reporter_func) for details.

The [Cook Book](CookBook.md) lists
[adapter code](CookBook.md/#unit_test_frameworks) for a number of popular
unit test frame works.

###  `bool trompeloeil::sequence::is_completed() const`

Member function of [`sequence`](#sequence_type) object, used to query if
the sequence it describes is completed or not.

`#include <trompeloeil/sequence.hpp>`

Example:

```Cpp
void test()
{
  auto seq = trompeloeil::sequence;
  mock_type mock;
  REQUIRE_CALL(mock, func1())
    .IN_SEQUENCE(seq);
  REQUIRE_CALL(mock, func2())
    .TIMES(100)
    .IN_SEQUENCE(seq);
  assert(!seq.is_completed()); // no calls yet
  mock.func1();
  assert(!seq.is_completed()); // only first call, one remaining
  mock.func2();
  assert(seq.is_completed());  // now sequence is completed
}
```

## Constants

###  `trompeloeil_movable_mock`

By adding a static constexpr bool member `trompeloeil_movable_mock` with the
value `true` to your mock struct/class, you make it move constructible. Note
that when a mock object is moved, any current expectations will be taken over
by the newly constructed mock object, but note also that if the implicitly
created lambdas associated with
[**`.WITH()`**](reference.md/#WITH),
[**`.SIDE_EFFECT()`**](reference.md/#SIDE_EFFECT),
[**`.RETURN()`**](reference.md/#RETURN) and
[**`.THROW()`**](reference.md/#THROW) and their **`LR_`** counter parts, refers
to member variables in the mock objects, they will continue to refer the old
moved from object.

`#include <trompeloeil/mock.hpp>`

```Cpp
class immobile
{
public:
  MAKE_MOCK1(func, void(int));
};

class movable
{
public:
  int i = 0;

  static constexpr bool trompeloeil_movable_mock = true;
  // allow move construction

  MAKE_MOCK1(func, void(int));
};

template <typename T>
T transfer(T t)
{
  return t;
}

test(...)
{
  auto m = transfer(immobile{}); // compilation error
  ...
}
test(...)
{
  movable m;
  auto e = NAMED_REQUIRE_CALL(m, func(3));
  auto mm = transfer(std::move(m));
   // A call to mm.func() now satisfies e
  ...
}
test(...)
{
  movable m{3};
  auto e = NAMED_REQUIRE_CALL(m, func(_))
    .LR_WITH(_1 == m.i);
  auto mm = transfer(std::move(m)); // Danger! e still refers to m.i.
  ...
}
```

Also, keep in mind the lifetime of expectations. If the lifetime of an
expectation is associated with the life of the moved-from object, your test
will likely fail, since the expectation object would then be destroyed before it
has been satisfied. Example:

```Cpp
class movable
{
public:
  static constexpr bool trompeloeil_movable_mock = true;

  MAKE_MOCK0(func, void());
};

movable setup()
{
  movable obj;
  REQUIRE_CALL(obj, func());
  return obj;
  // Expectation dies here, unsatisfied, failing the test
}

test(...)
{
  movable obj = setup(); // test fails when returning from setup()
  ...
}
```

Using
[**`NAMED_REQUIRE_CALL()`**](reference.md/#NAMED_REQUIRE_CALL),
[**`NAMED_ALLOW_CALL()`**](reference.md/#NAMED_ALLOW_CALL) or
[**`NAMED_FORBID_CALL()`**](reference.md/#NAMED_FORBID_CALL) can help, since
they make the expectation life times more visible.
