chell-0.4.0.1: A simple and intuitive library for automated testing.

Safe Haskell | None
Language | Haskell98

Test.Chell

Contents

- Main
- Test suites
  - Skipping some tests
- Basic testing library
  - Built-in assertions
- Custom test types
  - Test results
    - Failures
    - Failure locations
  - Test options

Description

Chell is a simple and intuitive library for automated testing. It natively supports assertion-based testing, and can use companion libraries such as `chell-quickcheck` to support more complex testing strategies.

An example test suite, which verifies the behavior of artithmetic operators.

    {-# LANGUAGE TemplateHaskell #-}

    import Test.Chell

    suite_Math :: Suite
    suite_Math = suite "math"
        [ test_Addition
        , test_Subtraction
        ]

    test_Addition :: Test
    test_Addition = assertions "addition" $ do
        $expect (equal (2 + 1) 3)
        $expect (equal (1 + 2) 3)

    test_Subtraction :: Test
    test_Subtraction = assertions "subtraction" $ do
        $expect (equal (2 - 1) 1)
        $expect (equal (1 - 2) (-1))

    main :: IO ()
    main = defaultMain [suite_Math]

    $ ghc --make chell-example.hs
    $ ./chell-example
    PASS: 2 tests run, 2 tests passed

Synopsis

- defaultMain :: [Suite] -> IO ()
- data Suite
- suite :: String -> [Test] -> Suite
- suiteName :: Suite -> String
- suiteTests :: Suite -> [Test]
- class SuiteOrTest a
- skipIf :: SuiteOrTest a => Bool -> a -> a
- skipWhen :: SuiteOrTest a => IO Bool -> a -> a
- data Assertions a
- assertions :: String -> Assertions a -> Test
- class IsAssertion a
- data Assertion
- assertionPassed :: Assertion
- assertionFailed :: String -> Assertion
- assert :: Q Exp
- expect :: Q Exp
- die :: Q Exp
- trace :: Q Exp
- note :: String -> String -> Assertions ()
- afterTest :: IO () -> Assertions ()
- requireLeft :: Q Exp
- requireRight :: Q Exp
- equal :: (Show a, Eq a) => a -> a -> Assertion
- notEqual :: (Eq a, Show a) => a -> a -> Assertion
- equalWithin :: (Real a, Show a) => a -> a -> a -> Assertion
- just :: Maybe a -> Assertion
- nothing :: Show a => Maybe a -> Assertion
- left :: Show b => Either a b -> Assertion
- right :: Show a => Either a b -> Assertion
- throws :: Exception err => (err -> Bool) -> IO a -> IO Assertion
- throwsEq :: (Eq err, Exception err, Show err) => err -> IO a -> IO Assertion
- greater :: (Ord a, Show a) => a -> a -> Assertion
- greaterEqual :: (Ord a, Show a) => a -> a -> Assertion
- lesser :: (Ord a, Show a) => a -> a -> Assertion
- lesserEqual :: (Ord a, Show a) => a -> a -> Assertion
- sameItems :: (Foldable container, Show item, Ord item) => container item -> container item -> Assertion
- equalItems :: (Foldable container, Show item, Ord item) => container item -> container item -> Assertion
- class IsText a
- equalLines :: (Ord a, IsText a) => a -> a -> Assertion
- equalLinesWith :: Ord a => (a -> [String]) -> a -> a -> Assertion
- data Test
- test :: String -> (TestOptions -> IO TestResult) -> Test
- testName :: Test -> String
- runTest :: Test -> TestOptions -> IO TestResult
- data TestResult
  - = TestPassed [(String, String)]
  - | TestSkipped
  - | TestFailed [(String, String)] [Failure]
  - | TestAborted [(String, String)] String
- data Failure
- failure :: Failure
- failureLocation :: Failure -> Maybe Location
- failureMessage :: Failure -> String
- data Location
- location :: Location
- locationFile :: Location -> String
- locationModule :: Location -> String
- locationLine :: Location -> Maybe Integer
- data TestOptions
- defaultTestOptions :: TestOptions
- testOptionSeed :: TestOptions -> Int
- testOptionTimeout :: TestOptions -> Maybe Int

# Main

defaultMain :: [Suite] -> IO () Source

A simple default main function, which runs a list of tests and logs statistics to stdout.

# Test suites

data Suite Source

A suite is a named collection of tests.

Note: earlier versions of Chell permitted arbitrary nesting of test suites. This feature proved too unwieldy, and was removed. A similar result can be achieved with `suiteTests`; see the documentation for `suite`.

Instances

Show Suite Source |
SuiteOrTest Suite Source |

suite :: String -> [Test] -> Suite Source

Define a new `Suite`, with the given name and children.

Note: earlier versions of Chell permitted arbitrary nesting of test suites. This feature proved too unwieldy, and was removed. A similar result can be achieved with `suiteTests`:

    test_Addition :: Test
    test_Subtraction :: Test
    test_Show :: Test

    suite_Math :: Suite
    suite_Math = suite "math"
        [ test_Addition
        , test_Subtraction
        ]

    suite_Prelude :: Suite
    suite_Prelude = suite "prelude"
        (
          [ test_Show
          ]
          ++ suiteTests suite_Math
        )

suiteName :: Suite -> String Source

Get a suite's name. Suite names may be any string, but are typically plain ASCII so users can easily type them on the command line.

    $ ghci chell-example.hs
    Ok, modules loaded: Main.

    *Main> suiteName tests_Math
    "math"

suiteTests :: Suite -> [Test] Source

Get the full list of tests contained within this `Suite`. Each test is given its full name within the test hierarchy, where names are separated by periods.

    $ ghci chell-example.hs
    Ok, modules loaded: Main.

    *Main> suiteTests tests_Math
    [Test "math.addition",Test "math.subtraction"]

## Skipping some tests

class SuiteOrTest a Source

Minimal complete definition

skipIf_, skipWhen_

Instances

SuiteOrTest Suite Source |
SuiteOrTest Test Source |

skipIf :: SuiteOrTest a => Bool -> a -> a Source

Conditionally skip tests. Use this to avoid commenting out tests which are currently broken, or do not work on the current platform.

    tests :: Suite
    tests = suite "tests"
        [ test_Foo
        , skipIf builtOnUnix test_WindowsSpecific
        , test_Bar
        ]

skipWhen :: SuiteOrTest a => IO Bool -> a -> a Source

Conditionally skip tests, depending on the result of a runtime check. The predicate is checked before each test is started.

    tests :: Suite
    tests = suite "tests"
        [ test_Foo
        , skipWhen noNetwork test_PingGoogle
        , test_Bar
        ]

# Basic testing library

data Assertions a Source

See `assertions`.

Instances

Monad Assertions Source |
Functor Assertions Source |
Applicative Assertions Source |
MonadIO Assertions Source |

assertions :: String -> Assertions a -> Test Source

Convert a sequence of pass/fail assertions into a runnable test.

    test_Equality :: Test
    test_Equality = assertions "equality" $ do
        $assert (1 == 1)
        $assert (equal 1 1)

class IsAssertion a Source

See `assert` and `expect`.

Minimal complete definition

runAssertion

Instances

IsAssertion Bool Source |
IsAssertion Assertion Source |
IsAssertion a => IsAssertion (IO a) Source |

data Assertion Source

A single pass/fail assertion. Failed assertions include an explanatory message.

Instances

Eq Assertion Source |
Show Assertion Source |
IsAssertion Assertion Source |

assertionPassed :: Assertion Source

See `Assertion`.

assertionFailed :: String -> Assertion Source

See `Assertion`.

assert :: Q Exp Source

Check an assertion. If the assertion fails, the test will immediately fail.

The assertion to check can be a boolean value, an `Assertion`, or an IO action returning one of the above.

`assert` is a Template Haskell macro, to retain the source-file location from which it was used. Its effective type is:

    $assert :: IsAssertion assertion => assertion -> Assertions ()

expect :: Q Exp Source

Check an assertion. If the assertion fails, the test will continue to run until it finishes, a call to `assert` fails, or the test runs `die`.

The assertion to check can be a boolean value, an `Assertion`, or an IO action returning one of the above.

`expect` is a Template Haskell macro, to retain the source-file location from which it was used. Its effective type is:

    $expect :: IsAssertion assertion => assertion -> Assertions ()

die :: Q Exp Source

Cause a test to immediately fail, with a message.

`die` is a Template Haskell macro, to retain the source-file location from which it was used. Its effective type is:

    $die :: String -> Assertions a

trace :: Q Exp Source

Print a message from within a test. This is just a helper for debugging, so you don't have to import `Debug.Trace`. Messages will be prefixed with the filename and line number where `$trace` was called.

`trace` is a Template Haskell macro, to retain the source-file location from which it was used. Its effective type is:

    $trace :: String -> Assertions ()

note :: String -> String -> Assertions () Source

Attach a note to a test run. Notes will be printed to stdout and included in reports, even if the test fails or aborts. Notes are useful for debugging failing tests.

afterTest :: IO () -> Assertions () Source

Register an IO action to be run after the test completes. This action will run even if the test failed or aborted.

requireLeft :: Q Exp Source

Require an `Either` value to be `Left`, and return its contents. If the value is `Right`, fail the test.

`requireLeft` is a Template Haskell macro, to retain the source-file location from which it was used. Its effective type is:

    $requireLeft :: Show b => Either a b -> Assertions a

requireRight :: Q Exp Source

Require an `Either` value to be `Right`, and return its contents. If the value is `Left`, fail the test.

`requireRight` is a Template Haskell macro, to retain the source-file location from which it was used. Its effective type is:

    $requireRight :: Show a => Either a b -> Assertions b

## Built-in assertions

equal :: (Show a, Eq a) => a -> a -> Assertion Source

Assert that two values are equal.

notEqual :: (Eq a, Show a) => a -> a -> Assertion Source

Assert that two values are not equal.

equalWithin Source

Arguments

:: (Real a, Show a) |
=> a |
-> a |
-> a | delta
-> Assertion |

Assert that two values are within some delta of each other.

just :: Maybe a -> Assertion Source

Assert that some value is `Just`.

nothing :: Show a => Maybe a -> Assertion Source

Assert that some value is `Nothing`.

left :: Show b => Either a b -> Assertion Source

Assert that some value is `Left`.

right :: Show a => Either a b -> Assertion Source

Assert that some value is `Right`.

throws :: Exception err => (err -> Bool) -> IO a -> IO Assertion Source

Assert that some computation throws an exception matching the provided predicate. This is mostly useful for exception types which do not have an instance for `Eq`, such as ``ErrorCall``.

throwsEq :: (Eq err, Exception err, Show err) => err -> IO a -> IO Assertion Source

Assert that some computation throws an exception equal to the given exception. This is better than just checking that the correct type was thrown, because the test can also verify the exception contains the correct information.

greater :: (Ord a, Show a) => a -> a -> Assertion Source

Assert a value is greater than another.

greaterEqual :: (Ord a, Show a) => a -> a -> Assertion Source

Assert a value is greater than or equal to another.

lesser :: (Ord a, Show a) => a -> a -> Assertion Source

Assert a value is less than another.

lesserEqual :: (Ord a, Show a) => a -> a -> Assertion Source

Assert a value is less than or equal to another.

sameItems :: (Foldable container, Show item, Ord item) => container item -> container item -> Assertion Source

Assert that two containers have the same items, in any order.

equalItems :: (Foldable container, Show item, Ord item) => container item -> container item -> Assertion Source

Assert that two containers have the same items, in the same order.

class IsText a Source

Class for types which can be treated as text; see `equalLines`.

Minimal complete definition

toLines, unpack

Instances

IsText String Source |
IsText ByteString Source | Uses `Data.ByteString.Char8`
IsText ByteString Source | Uses `Data.ByteString.Lazy.Char8`
IsText Text Source |
IsText Text Source |

equalLines :: (Ord a, IsText a) => a -> a -> Assertion Source

Assert that two pieces of text are equal. This uses a diff algorithm to check line-by-line, so the error message will be easier to read on large inputs.

equalLinesWith :: Ord a => (a -> [String]) -> a -> a -> Assertion Source

Variant of `equalLines` which allows a user-specified line-splitting predicate.

# Custom test types

data Test Source

A `Test` is, essentially, an IO action that returns a `TestResult`. Tests are aggregated into suites (see `Suite`).

Instances

Show Test Source |
SuiteOrTest Test Source |

test :: String -> (TestOptions -> IO TestResult) -> Test Source

Define a test, with the given name and implementation.

testName :: Test -> String Source

Get the name a test was given when it was defined; see `test`.

runTest :: Test -> TestOptions -> IO TestResult Source

Run a test, wrapped in error handlers. This will return `TestAborted` if the test throws an exception or times out.

## Test results

data TestResult Source

The result of running a test.

To support future extensions to the testing API, any users of this module who pattern-match against the `TestResult` constructors should include a default case. If no default case is provided, a warning will be issued.

Constructors

TestPassed [(String, String)] | The test passed, and generated the given notes.
TestSkipped | The test did not run, because it was skipped with `skipIf` or `skipWhen`.
TestFailed [(String, String)] [Failure] | The test failed, generating the given notes and failures.
TestAborted [(String, String)] String | The test aborted with an error message, and generated the given notes.

Instances

Eq TestResult Source |
Show TestResult Source |

### Failures

data Failure Source

Contains details about a test failure.

Instances

Eq Failure Source |
Show Failure Source |

failure :: Failure Source

An empty `Failure`; use the field accessors to populate this value.

failureLocation :: Failure -> Maybe Location Source

If given, the location of the failing assertion, expectation, etc.

`failureLocation` is a field accessor, and can be used to update a `Failure` value.

failureMessage :: Failure -> String Source

If given, a message which explains why the test failed.

`failureMessage` is a field accessor, and can be used to update a `Failure` value.

### Failure locations

data Location Source

Contains details about a location in the test source file.

Instances

Eq Location Source |
Show Location Source |

location :: Location Source

An empty `Location`; use the field accessors to populate this value.

locationFile :: Location -> String Source

A path to a source file, or empty if not provided.

`locationFile` is a field accessor, and can be used to update a `Location` value.

locationModule :: Location -> String Source

A Haskell module name, or empty if not provided.

`locationModule` is a field accessor, and can be used to update a `Location` value.

locationLine :: Location -> Maybe Integer Source

A line number, or Nothing if not provided.

`locationLine` is a field accessor, and can be used to update a `Location` value.

## Test options

data TestOptions Source

Test options are passed to each test, and control details about how the test should be run.

Instances

Eq TestOptions Source |
Show TestOptions Source |

defaultTestOptions :: TestOptions Source

Default test options.

    $ ghci
    Prelude> import Test.Chell

    Test.Chell> testOptionSeed defaultTestOptions
    0

    Test.Chell> testOptionTimeout defaultTestOptions
    Nothing

testOptionSeed :: TestOptions -> Int Source

Get the RNG seed for this test run. The seed is generated once, in `defaultMain`, and used for all tests. It is also logged to reports using a note.

When using `defaultMain`, users may specify a seed using the `--seed` command-line option.

`testOptionSeed` is a field accessor, and can be used to update a `TestOptions` value.

testOptionTimeout :: TestOptions -> Maybe Int Source

An optional timeout, in millseconds. Tests which run longer than this timeout will be aborted.

When using `defaultMain`, users may specify a timeout using the `--timeout` command-line option.

`testOptionTimeout` is a field accessor, and can be used to update a `TestOptions` value.