# Class: Mocha::Expectation

Inherits:
  Object
  - Object
  - Mocha::Expectation
  show all

Defined in:
  lib/mocha/expectation.rb

## Overview

Methods on expectations returned from Mock#expects, Mock#stubs, ObjectMethods#expects and ObjectMethods#stubs.

## Instance Method Summary collapse

- #at_least(minimum_number_of_times) ⇒ Expectation

  Modifies expectation so that the expected method must be called at least a `minimum_number_of_times`.

- #at_least_once ⇒ Expectation

  Modifies expectation so that the expected method must be called at least once.

- #at_most(maximum_number_of_times) ⇒ Expectation

  Modifies expectation so that the expected method must be called at most a `maximum_number_of_times`.

- #at_most_once ⇒ Expectation

  Modifies expectation so that the expected method must be called at most once.

- #in_sequence(*sequences) ⇒ Expectation

  Constrains the expectation so that it must be invoked at the current point in the `sequence`.

- #multiple_yields(*parameter_groups) ⇒ Expectation

  Modifies expectation so that when the expected method is called, it yields multiple times per invocation with the specified `parameter_groups`.

- #never ⇒ Expectation

  Modifies expectation so that the expected method must never be called.

- #once ⇒ Expectation

  Modifies expectation so that the expected method must be called exactly once.

- #raises(exception = RuntimeError, message = nil) ⇒ Expectation

  Modifies expectation so that when the expected method is called, it raises the specified `exception` with the specified `message` i.e.

- #returns(*values) ⇒ Expectation

  Modifies expectation so that when the expected method is called, it returns the specified `value`.

- #then(*parameters) ⇒ Expectation

  The same expectation, thereby allowing invocations of other Expectation methods to be chained.

- #throws(tag, object = nil) ⇒ Expectation

  Modifies expectation so that when the expected method is called, it throws the specified `tag` with the specific return value `object` i.e.

- #times(range) ⇒ Expectation

  Modifies expectation so that the number of calls to the expected method must be within a specific `range`.

- #twice ⇒ Expectation

  Modifies expectation so that the expected method must be called exactly twice.

- #when(state_predicate) ⇒ Expectation

  Constrains the expectation to occur only when the `state_machine` is in the state specified by `state_name`.

- #with(*expected_parameters) {|actual_parameters| ... } ⇒ Expectation

  Modifies expectation so that the expected method must be called with `expected_parameters`.

- #yields(*parameters) ⇒ Expectation

  Modifies expectation so that when the expected method is called, it yields with the specified `parameters`.

## Instance Method Details

### #at_least(minimum_number_of_times) ⇒ `Expectation`

Modifies expectation so that the expected method must be called at least a `minimum_number_of_times`.

Examples:

Expected method must be called at least twice.

    object = mock()
    object.expects(:expected_method).at_least(2)
    3.times { object.expected_method }
    # => verify succeeds

    object = mock()
    object.expects(:expected_method).at_least(2)
    object.expected_method
    # => verify fails

Parameters:

- minimum_number_of_times (`Integer`) —

  minimum number of expected invocations.

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

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    # File 'lib/mocha/expectation.rb', line 130

    def at_least(minimum_number_of_times)
      @cardinality = Cardinality.at_least(minimum_number_of_times)
      self
    end

### #at_least_once ⇒ `Expectation`

Modifies expectation so that the expected method must be called at least once.

Examples:

Expected method must be called at least once.

    object = mock()
    object.expects(:expected_method).at_least_once
    object.expected_method
    # => verify succeeds

    object = mock()
    object.expects(:expected_method).at_least_once
    # => verify fails

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

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    # File 'lib/mocha/expectation.rb', line 148

    def at_least_once
      at_least(1)
      self
    end

### #at_most(maximum_number_of_times) ⇒ `Expectation`

Modifies expectation so that the expected method must be called at most a `maximum_number_of_times`.

Examples:

Expected method must be called at most twice.

    object = mock()
    object.expects(:expected_method).at_most(2)
    2.times { object.expected_method }
    # => verify succeeds

    object = mock()
    object.expects(:expected_method).at_most(2)
    3.times { object.expected_method } # => unexpected invocation

Parameters:

- maximum_number_of_times (`Integer`) —

  maximum number of expected invocations.

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

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    # File 'lib/mocha/expectation.rb', line 167

    def at_most(maximum_number_of_times)
      @cardinality = Cardinality.at_most(maximum_number_of_times)
      self
    end

### #at_most_once ⇒ `Expectation`

Modifies expectation so that the expected method must be called at most once.

Examples:

Expected method must be called at most once.

    object = mock()
    object.expects(:expected_method).at_most_once
    object.expected_method
    # => verify succeeds

    object = mock()
    object.expects(:expected_method).at_most_once
    2.times { object.expected_method } # => unexpected invocation

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

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    # File 'lib/mocha/expectation.rb', line 185

    def at_most_once
      at_most(1)
      self
    end

### #in_sequence(*sequences) ⇒ `Expectation`

Constrains the expectation so that it must be invoked at the current point in the `sequence`.

To expect a sequence of invocations, write the expectations in order and add the `in_sequence(sequence)` clause to each one.

Expectations in a `sequence` can have any invocation count.

If an expectation in a sequence is stubbed, rather than expected, it can be skipped in the `sequence`.

An expected method can appear in multiple sequences.

Examples:

Ensure methods are invoked in a specified order.

    breakfast = sequence('breakfast')

    egg = mock('egg')
    egg.expects(:crack).in_sequence(breakfast)
    egg.expects(:fry).in_sequence(breakfast)
    egg.expects(:eat).in_sequence(breakfast)

Parameters:

- sequences (`*Array<Sequence>`) —

  sequences in which expected method should appear.

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

See Also:

- API#sequence

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    # File 'lib/mocha/expectation.rb', line 492

    def in_sequence(*sequences)
      sequences.each { |sequence| add_in_sequence_ordering_constraint(sequence) }
      self
    end

### #multiple_yields(*parameter_groups) ⇒ `Expectation`

Modifies expectation so that when the expected method is called, it yields multiple times per invocation with the specified `parameter_groups`.

Examples:

When the `expected_method` is called, the stub will invoke the block twice, the first time it passes `'result_1'`, `'result_2'` as the parameters, and the second time it passes 'result_3' as the parameters.

    object = mock()
    object.expects(:expected_method).multiple_yields(['result_1', 'result_2'], ['result_3'])
    yielded_values = []
    object.expected_method { |*values| yielded_values << values }
    yielded_values # => [['result_1', 'result_2'], ['result_3]]

Yield different groups of parameters on different invocations of the expected method.

    object = mock()
    object.stubs(:expected_method).multiple_yields([1, 2], [3]).then.multiple_yields([4], [5, 6])
    yielded_values_from_first_invocation = []
    yielded_values_from_second_invocation = []
    object.expected_method { |*values| yielded_values_from_first_invocation << values } # first invocation
    object.expected_method { |*values| yielded_values_from_second_invocation << values } # second invocation
    yielded_values_from_first_invocation # => [[1, 2], [3]]
    yielded_values_from_second_invocation # => [[4], [5, 6]]

Parameters:

- parameter_groups (`*Array<Array>`) —

  each element of `parameter_groups` should iself be an `Array` representing the parameters to be passed to the block for a single yield.

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

See Also:

- #then

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    # File 'lib/mocha/expectation.rb', line 277

    def multiple_yields(*parameter_groups)
      @yield_parameters.multiple_add(*parameter_groups)
      self
    end

### #never ⇒ `Expectation`

Modifies expectation so that the expected method must never be called.

Examples:

Expected method must never be called.

    object = mock()
    object.expects(:expected_method).never
    object.expected_method # => unexpected invocation

    object = mock()
    object.expects(:expected_method).never
    # => verify succeeds

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

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    # File 'lib/mocha/expectation.rb', line 110

    def never
      @cardinality = Cardinality.exactly(0)
      self
    end

### #once ⇒ `Expectation`

Modifies expectation so that the expected method must be called exactly once.

Note that this is the default behaviour for an expectation, but you may wish to use it for clarity/emphasis.

Examples:

Expected method must be invoked exactly once.

    object = mock()
    object.expects(:expected_method).once
    object.expected_method
    # => verify succeeds

    object = mock()
    object.expects(:expected_method).once
    object.expected_method
    object.expected_method # => unexpected invocation

    object = mock()
    object.expects(:expected_method).once
    # => verify fails

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

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    # File 'lib/mocha/expectation.rb', line 93

    def once
      @cardinality = Cardinality.exactly(1)
      self
    end

### #raises ⇒ `Expectation` #raises(exception) ⇒ `Expectation` #raises(exception, message) ⇒ `Expectation`

Modifies expectation so that when the expected method is called, it raises the specified `exception` with the specified `message` i.e. calls `Kernel#raise(exception, message)`.

Examples:

Raise specified exception if expected method is invoked.

    object = stub()
    object.stubs(:expected_method).raises(Exception, 'message')
    object.expected_method # => raises exception of class Exception and with message 'message'

Raise custom exception with extra constructor parameters by passing in an instance of the exception.

    object = stub()
    object.stubs(:expected_method).raises(MyException.new('message', 1, 2, 3))
    object.expected_method # => raises the specified instance of MyException

Raise different exceptions on consecutive invocations of the expected method.

    object = stub()
    object.stubs(:expected_method).raises(Exception1).then.raises(Exception2)
    object.expected_method # => raises exception of class Exception1
    object.expected_method # => raises exception of class Exception2

Raise an exception on first invocation of expected method and then return values on subsequent invocations.

    object = stub()
    object.stubs(:expected_method).raises(Exception).then.returns(2, 3)
    object.expected_method # => raises exception of class Exception1
    object.expected_method # => 2
    object.expected_method # => 3

Parameters:

- exception (`Class`, `Exception`, `String`, `#exception`) (defaults to: `RuntimeError`) —

  exception to be raised or message to be passed to RuntimeError.

- message (`String`) (defaults to: `nil`) —

  exception message.

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

See Also:

- Kernel#raise
- #then

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    # File 'lib/mocha/expectation.rb', line 364

    def raises(exception = RuntimeError, message = nil)
      @return_values += ReturnValues.new(ExceptionRaiser.new(exception, message))
      self
    end

### #returns(value) ⇒ `Expectation` #returns(*values) ⇒ `Expectation`

Modifies expectation so that when the expected method is called, it returns the specified `value`.

Examples:

Return the same value on every invocation.

    object = mock()
    object.stubs(:stubbed_method).returns('result')
    object.stubbed_method # => 'result'
    object.stubbed_method # => 'result'

Return a different value on consecutive invocations.

    object = mock()
    object.stubs(:stubbed_method).returns(1, 2)
    object.stubbed_method # => 1
    object.stubbed_method # => 2

Alternative way to return a different value on consecutive invocations.

    object = mock()
    object.stubs(:expected_method).returns(1, 2).then.returns(3)
    object.expected_method # => 1
    object.expected_method # => 2
    object.expected_method # => 3

May be called in conjunction with #raises on the same expectation.

    object = mock()
    object.stubs(:expected_method).returns(1, 2).then.raises(Exception)
    object.expected_method # => 1
    object.expected_method # => 2
    object.expected_method # => raises exception of class Exception1

Note that in Ruby a method returning multiple values is exactly equivalent to a method returning an `Array` of those values.

    object = mock()
    object.stubs(:expected_method).returns([1, 2])
    x, y = object.expected_method
    x # => 1
    y # => 2

Overloads:

- #returns(value) ⇒ `Expectation`

  Parameters:

  - value (`Object`) —

    value to return on invocation of expected method.

- #returns(*values) ⇒ `Expectation`

  Parameters:

  - values (`*Array`) —

    values to return on consecutive invocations of expected method.

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

See Also:

- #then

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    # File 'lib/mocha/expectation.rb', line 324

    def returns(*values)
      @return_values += ReturnValues.build(*values)
      self
    end

### #then ⇒ `Expectation` #then(state_machine.is(state_name)) ⇒ `Expectation`

Returns the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

Examples:

Using #then as syntactic sugar when specifying values to be returned and exceptions to be raised on consecutive invocations of the expected method.

    object = mock()
    object.stubs(:expected_method).returns(1, 2).then.raises(Exception).then.returns(4)
    object.expected_method # => 1
    object.expected_method # => 2
    object.expected_method # => raises exception of class Exception
    object.expected_method # => 4

Using #then to change the `state` of a `state_machine` on the invocation of an expected method.

    power = states('power').starts_as('off')

    radio = mock('radio')
    radio.expects(:switch_on).then(power.is('on'))
    radio.expects(:select_channel).with('BBC Radio 4').when(power.is('on'))
    radio.expects(:adjust_volume).with(+5).when(power.is('on'))
    radio.expects(:select_channel).with('BBC World Service').when(power.is('on'))
    radio.expects(:adjust_volume).with(-5).when(power.is('on'))
    radio.expects(:switch_off).then(power.is('off'))

Overloads:

- #then ⇒ `Expectation`

  Used as syntactic sugar to improve readability. It has no effect on state of the expectation.

- #then(state_machine.is(state_name)) ⇒ `Expectation`

  Used to change the `state_machine` to the state specified by `state_name` when the expected invocation occurs.

  Parameters:

  - state_machine.is(state_name) (`StateMachine::State`) —

    provides a mechanism to change the `state_machine` into the state specified by `state_name` when the expected method is invoked.

  See Also:

  - API#states
  - StateMachine
  - #when

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

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    # File 'lib/mocha/expectation.rb', line 438

    def then(*parameters)
      if parameters.length == 1
        state = parameters.first
        add_side_effect(ChangeStateSideEffect.new(state))
      end
      self
    end

### #throw(tag) ⇒ `Expectation` #throw(tag, object) ⇒ `Expectation`

Modifies expectation so that when the expected method is called, it throws the specified `tag` with the specific return value `object` i.e. calls `Kernel#throw(tag, object)`.

Examples:

Throw tag when expected method is invoked.

    object = stub()
    object.stubs(:expected_method).throws(:done)
    object.expected_method # => throws tag :done

Throw tag with return value `object` c.f. `Kernel#throw`.

    object = stub()
    object.stubs(:expected_method).throws(:done, 'result')
    object.expected_method # => throws tag :done and causes catch block to return 'result'

Throw different tags on consecutive invocations of the expected method.

    object = stub()
    object.stubs(:expected_method).throws(:done).then.throws(:continue)
    object.expected_method # => throws :done
    object.expected_method # => throws :continue

Throw tag on first invocation of expected method and then return values for subsequent invocations.

    object = stub()
    object.stubs(:expected_method).throws(:done).then.returns(2, 3)
    object.expected_method # => throws :done
    object.expected_method # => 2
    object.expected_method # => 3

Parameters:

- tag (`Symbol`, `String`) —

  tag to throw to transfer control to the active catch block.

- object (`Object`) (defaults to: `nil`) —

  return value for the catch block.

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

See Also:

- Kernel#throw
- #then

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    # File 'lib/mocha/expectation.rb', line 403

    def throws(tag, object = nil)
      @return_values += ReturnValues.new(Thrower.new(tag, object))
      self
    end

### #times(range) ⇒ `Expectation`

Modifies expectation so that the number of calls to the expected method must be within a specific `range`.

Examples:

Specifying a specific number of expected invocations.

    object = mock()
    object.expects(:expected_method).times(3)
    3.times { object.expected_method }
    # => verify succeeds

    object = mock()
    object.expects(:expected_method).times(3)
    2.times { object.expected_method }
    # => verify fails

Specifying a range in the number of expected invocations.

    object = mock()
    object.expects(:expected_method).times(2..4)
    3.times { object.expected_method }
    # => verify succeeds

    object = mock()
    object.expects(:expected_method).times(2..4)
    object.expected_method
    # => verify fails

Parameters:

- range (`Range`, `Integer`) —

  specifies the allowable range in the number of expected invocations.

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

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    # File 'lib/mocha/expectation.rb', line 42

    def times(range)
      @cardinality = Cardinality.times(range)
      self
    end

### #twice ⇒ `Expectation`

Modifies expectation so that the expected method must be called exactly twice.

Examples:

Expected method must be invoked exactly twice.

    object = mock()
    object.expects(:expected_method).twice
    object.expected_method
    object.expected_method
    # => verify succeeds

    object = mock()
    object.expects(:expected_method).twice
    object.expected_method
    object.expected_method
    object.expected_method # => unexpected invocation

    object = mock()
    object.expects(:expected_method).twice
    object.expected_method
    # => verify fails

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

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    # File 'lib/mocha/expectation.rb', line 68

    def twice
      @cardinality = Cardinality.exactly(2)
      self
    end

### #when(state_predicate) ⇒ `Expectation`

Constrains the expectation to occur only when the `state_machine` is in the state specified by `state_name`.

Examples:

Using #when to only allow invocation of methods when “power” state machine is in the “on” state.

    power = states('power').starts_as('off')

    radio = mock('radio')
    radio.expects(:switch_on).then(power.is('on'))
    radio.expects(:select_channel).with('BBC Radio 4').when(power.is('on'))
    radio.expects(:adjust_volume).with(+5).when(power.is('on'))
    radio.expects(:select_channel).with('BBC World Service').when(power.is('on'))
    radio.expects(:adjust_volume).with(-5).when(power.is('on'))
    radio.expects(:switch_off).then(power.is('off'))

Parameters:

- state_machine.is(state_name) (`StateMachine::StatePredicate`) —

  provides a mechanism to determine whether the `state_machine` is in the state specified by `state_name` when the expected method is invoked.

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

See Also:

- API#states
- StateMachine
- #then

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    # File 'lib/mocha/expectation.rb', line 465

    def when(state_predicate)
      add_ordering_constraint(InStateOrderingConstraint.new(state_predicate))
      self
    end

### #with(*expected_parameters) {|actual_parameters| ... } ⇒ `Expectation`

Modifies expectation so that the expected method must be called with `expected_parameters`.

May be used with parameter matchers in ParameterMatchers.

Examples:

Expected method must be called with expected parameters.

    object = mock()
    object.expects(:expected_method).with(:param1, :param2)
    object.expected_method(:param1, :param2)
    # => verify succeeds

    object = mock()
    object.expects(:expected_method).with(:param1, :param2)
    object.expected_method(:param3)
    # => verify fails

Expected method must be called with a value divisible by 4.

    object = mock()
    object.expects(:expected_method).with() { |value| value % 4 == 0 }
    object.expected_method(16)
    # => verify succeeds

    object = mock()
    object.expects(:expected_method).with() { |value| value % 4 == 0 }
    object.expected_method(17)
    # => verify fails

Parameters:

- expected_parameters (`*Array`) —

  parameters expected.

Yields:

- optional block specifying custom matching.

Yield Parameters:

- actual_parameters (`*Array`) —

  parameters with which expected method was invoked.

Yield Returns:

- (`Boolean`) —

  `true` if `actual_parameters` are acceptable.

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

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    # File 'lib/mocha/expectation.rb', line 221

    def with(*expected_parameters, &matching_block)
      @parameters_matcher = ParametersMatcher.new(expected_parameters, &matching_block)
      self
    end

### #yields(*parameters) ⇒ `Expectation`

Modifies expectation so that when the expected method is called, it yields with the specified `parameters`.

May be called multiple times on the same expectation for consecutive invocations.

Examples:

Yield parameters when expected method is invoked.

    object = mock()
    object.expects(:expected_method).yields('result')
    yielded_value = nil
    object.expected_method { |value| yielded_value = value }
    yielded_value # => 'result'

Yield different parameters on different invocations of the expected method.

    object = mock()
    object.stubs(:expected_method).yields(1).then.yields(2)
    yielded_values_from_first_invocation = []
    yielded_values_from_second_invocation = []
    object.expected_method { |value| yielded_values_from_first_invocation << value } # first invocation
    object.expected_method { |value| yielded_values_from_second_invocation << value } # second invocation
    yielded_values_from_first_invocation # => [1]
    yielded_values_from_second_invocation # => [2]

Parameters:

- parameters (`*Array`) —

  parameters to be yielded.

Returns:

- (`Expectation`) —

  the same expectation, thereby allowing invocations of other Mocha::Expectation methods to be chained.

See Also:

- #then

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    # File 'lib/mocha/expectation.rb', line 250

    def yields(*parameters)
      @yield_parameters.add(*parameters)
      self
    end