class Mocha::Mock
Traditional mock object.
{expects} and {stubs} return an {Expectation} which can be further modified by methods on {Expectation}.
{responds_like} and {responds_like_instance_of} both return a {Mock}, and can therefore, be chained to the original creation methods in {API}. They force the mock to indicate what it is supposed to be mocking, thus making it a safer verifying mock. They check that the underlying responder
will actually respond to the methods being stubbed, throwing a NoMethodError
upon invocation otherwise.
Stubs and expectations are basically the same thing. A stub is just an expectation of zero or more invocations. The {#stubs} method is syntactic sugar to make the intent of the test more explicit.
When a method is invoked on a mock object, the mock object searches through its expectations from newest to oldest to find one that matches the invocation. After the invocation, the matching expectation might stop matching further invocations. For example, an +expects(:foo).once+ expectation only matches once and will be ignored on future invocations while an +expects(:foo).at_least_once+ expectation will always be matched against invocations.
This scheme allows you to:
-
Set up default stubs in your the
setup
method of your test class and override some of those stubs in individual tests. -
Set up different
once
expectations for the same method with different action per invocation. However, it’s better to use the {Expectation#returns} method with multiple arguments to do this, as described below.
However, there are some possible “gotchas” caused by this scheme:
-
if you create an expectation and then a stub for the same method, the stub will always override the expectation and the expectation will never be met.
-
if you create a stub and then an expectation for the same method, the expectation will match, and when it stops matching the stub will be used instead, possibly masking test failures.
-
if you create different expectations for the same method, they will be invoked in the opposite order than that in which they were specified, rather than the same order.
The best thing to do is not set up multiple expectations and stubs for the same method with exactly the same matchers. Instead, use the {Expectation#returns} method with multiple arguments to create multiple actions for a method. You can also chain multiple calls to {Expectation#returns} and {Expectation#raises} (along with syntactic sugar {Expectation#then} if desired).
@example
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
If you want to specify more complex ordering or order invocations across different mock objects, use the {Expectation#in_sequence} method to explicitly define a total or partial ordering of invocations.
Attributes
@private
Public Class Methods
@private
# File lib/mocha/mock.rb, line 272 def initialize(mockery, name = nil, receiver = nil) @mockery = mockery @name = name || DefaultName.new(self) @receiver = receiver || DefaultReceiver.new(self) @expectations = ExpectationList.new @everything_stubbed = false @responder = nil @unexpected_invocation = nil @expired = false end
Public Instance Methods
@private
# File lib/mocha/mock.rb, line 296 def __expectations__ @expectations end
@private
# File lib/mocha/mock.rb, line 342 def __expire__ @expired = true end
@private
# File lib/mocha/mock.rb, line 337 def __verified__?(assertion_counter = nil) @expectations.verified?(assertion_counter) end
@private
# File lib/mocha/mock.rb, line 306 def all_expectations @receiver.mocks.inject(ExpectationList.new) { |e, m| e + m.__expectations__ } end
@private
# File lib/mocha/mock.rb, line 362 def any_expectations? @expectations.any? end
@private
# File lib/mocha/mock.rb, line 357 def ensure_method_not_already_defined(method_name) __singleton_class__.send(:undef_method, method_name) if __singleton_class__.method_defined?(method_name) || __singleton_class__.private_method_defined?(method_name) end
Adds an expectation that the specified method must be called exactly once with any parameters.
@return [Expectation] last-built expectation which can be further modified by methods on {Expectation}.
@overload def expects(method_name)
@param [Symbol,String] method_name name of expected method
@overload def expects(expected_methods_vs_return_values)
@param [Hash] expected_methods_vs_return_values expected method name symbols as keys and corresponding return values as values - these expectations are setup as if {#expects} were called multiple times.
@example Expected method invoked once so no error raised
object = mock() object.expects(:expected_method) object.expected_method
@example Expected method not invoked so error raised
object = mock() object.expects(:expected_method) # error raised when test completes, because expected_method not called exactly once
@example Expected method invoked twice so error raised
object = mock() object.expects(:expected_method) object.expected_method object.expected_method # => error raised when expected method invoked second time
@example Setup multiple expectations using expected_methods_vs_return_values
.
object = mock() object.expects(:expected_method_one => :result_one, :expected_method_two => :result_two) # is exactly equivalent to object = mock() object.expects(:expected_method_one).returns(:result_one) object.expects(:expected_method_two).returns(:result_two)
# File lib/mocha/mock.rb, line 109 def expects(method_name_or_hash, backtrace = nil) expectation = nil iterator = ArgumentIterator.new(method_name_or_hash) iterator.each do |*args| method_name = args.shift ensure_method_not_already_defined(method_name) expectation = Expectation.new(self, method_name, backtrace) expectation.returns(args.shift) unless args.empty? @expectations.add(expectation) end expectation end
@private
# File lib/mocha/mock.rb, line 316 def handle_method_call(symbol, arguments, block) check_expiry check_responder_responds_to(symbol) invocation = Invocation.new(self, symbol, arguments, block) if (matching_expectation_allowing_invocation = all_expectations.match_allowing_invocation(invocation)) matching_expectation_allowing_invocation.invoke(invocation) elsif (matching_expectation = all_expectations.match(invocation)) || (!matching_expectation && !@everything_stubbed) raise_unexpected_invocation_error(invocation, matching_expectation) end end
@private
# File lib/mocha/mock.rb, line 352 def inspect mocha_inspect end
@private
# File lib/mocha/mock.rb, line 311 def method_missing(symbol, *arguments, &block) # rubocop:disable Style/MethodMissingSuper handle_method_call(symbol, arguments, block) end
@private
# File lib/mocha/mock.rb, line 347 def mocha_inspect @name.mocha_inspect end
@private
# File lib/mocha/mock.rb, line 328 def respond_to_missing?(symbol, include_all) if @responder @responder.respond_to?(symbol, include_all) else @everything_stubbed || all_expectations.matches_method?(symbol) end end
Constrains the {Mock} instance so that it can only expect or stub methods to which responder
responds. The constraint is only applied at method invocation time.
A NoMethodError
will be raised if the responder
does not #respond_to?
a method invocation (even if the method has been expected or stubbed).
The {Mock} instance will delegate its #respond_to?
method to the responder
.
Note that the methods on responder
are never actually invoked.
@param [Object, respond_to?] responder an object used to determine whether {Mock} instance should #respond_to?
to an invocation. @return [Mock] the same {Mock} instance, thereby allowing invocations of other {Mock} methods to be chained. @see responds_like_instance_of
@example Normal mocking
sheep = mock('sheep') sheep.expects(:chew) sheep.expects(:foo) sheep.respond_to?(:chew) # => true sheep.respond_to?(:foo) # => true sheep.chew sheep.foo # no error raised
@example Using {#responds_like} with an instance method
class Sheep def chew(grass); end end sheep = mock('sheep') sheep.responds_like(Sheep.new) sheep.expects(:chew) sheep.expects(:foo) sheep.respond_to?(:chew) # => true sheep.respond_to?(:foo) # => false sheep.chew sheep.foo # => raises NoMethodError exception
@example Using {#responds_like} with a class method
class Sheep def self.number_of_legs; end end sheep_class = mock('sheep_class') sheep_class.responds_like(Sheep) sheep_class.stubs(:number_of_legs).returns(4) sheep_class.expects(:foo) sheep_class.respond_to?(:number_of_legs) # => true sheep_class.respond_to?(:foo) # => false sheep_class.number_of_legs # => 4 sheep_class.foo # => raises NoMethodError exception
# File lib/mocha/mock.rb, line 234 def responds_like(responder) @responder = responder self end
Constrains the {Mock} instance so that it can only expect or stub methods to which an instance of the responder_class
responds. The constraint is only applied at method invocation time. Note that the responder instance is instantiated using +Class#allocate+.
A NoMethodError
will be raised if the responder instance does not #respond_to?
a method invocation (even if the method has been expected or stubbed).
The {Mock} instance will delegate its #respond_to?
method to the responder instance.
Note that the methods on the responder instance are never actually invoked.
@param [Class] responder_class a class used to determine whether {Mock} instance should #respond_to?
to an invocation. @return [Mock] the same {Mock} instance, thereby allowing invocations of other {Mock} methods to be chained. @see responds_like
@example Using {#responds_like_instance_of}
class Sheep def initialize raise "some awkward code we don't want to call" end def chew(grass); end end sheep = mock('sheep') sheep.responds_like_instance_of(Sheep) sheep.expects(:chew) sheep.expects(:foo) sheep.respond_to?(:chew) # => true sheep.respond_to?(:foo) # => false sheep.chew sheep.foo # => raises NoMethodError exception
# File lib/mocha/mock.rb, line 267 def responds_like_instance_of(responder_class) responds_like(responder_class.allocate) end
@private
# File lib/mocha/mock.rb, line 301 def stub_everything @everything_stubbed = true end
Adds an expectation that the specified method may be called any number of times with any parameters.
@return [Expectation] last-built expectation which can be further modified by methods on {Expectation}.
@overload def stubs(method_name)
@param [Symbol,String] method_name name of stubbed method
@overload def stubs(stubbed_methods_vs_return_values)
@param [Hash] stubbed_methods_vs_return_values stubbed method name symbols as keys and corresponding return values as values - these stubbed methods are setup as if {#stubs} were called multiple times.
@example No error raised however many times stubbed method is invoked
object = mock() object.stubs(:stubbed_method) object.stubbed_method object.stubbed_method # no error raised
@example Setup multiple expectations using stubbed_methods_vs_return_values
.
object = mock() object.stubs(:stubbed_method_one => :result_one, :stubbed_method_two => :result_two) # is exactly equivalent to object = mock() object.stubs(:stubbed_method_one).returns(:result_one) object.stubs(:stubbed_method_two).returns(:result_two)
# File lib/mocha/mock.rb, line 147 def stubs(method_name_or_hash, backtrace = nil) expectation = nil iterator = ArgumentIterator.new(method_name_or_hash) iterator.each do |*args| method_name = args.shift ensure_method_not_already_defined(method_name) expectation = Expectation.new(self, method_name, backtrace) expectation.at_least(0) expectation.returns(args.shift) unless args.empty? @expectations.add(expectation) end expectation end
Removes the specified stubbed methods (added by calls to {#expects} or {#stubs}) and all expectations associated with them.
@param [Array<Symbol>] method_names names of methods to unstub.
@example Invoking an unstubbed method causes error to be raised
object = mock('mock') object.stubs(:stubbed_method).returns(:result_one) object.stubbed_method # => :result_one object.unstub(:stubbed_method) object.stubbed_method # => unexpected invocation: #<Mock:mock>.stubbed_method()
@example Unstubbing multiple methods.
multiplier.unstub(:double, :triple) # exactly equivalent to multiplier.unstub(:double) multiplier.unstub(:triple)
# File lib/mocha/mock.rb, line 179 def unstub(*method_names) method_names.each do |method_name| @expectations.remove_all_matching_method(method_name) end end
Private Instance Methods
# File lib/mocha/mock.rb, line 385 def check_expiry if @expired # rubocop:disable Style/GuardClause Deprecation.warning( "#{mocha_inspect} was instantiated in one test but it is receiving invocations within another test.", ' This can lead to unintended interactions between tests and hence unexpected test failures.', ' Ensure that every test correctly cleans up any state that it introduces.', ' A Mocha::StubbingError will be raised in this scenario in the future.' ) end end
# File lib/mocha/mock.rb, line 379 def check_responder_responds_to(symbol) if @responder && !@responder.respond_to?(symbol) # rubocop:disable Style/GuardClause raise NoMethodError, "undefined method `#{symbol}' for #{mocha_inspect} which responds like #{@responder.mocha_inspect}" end end
# File lib/mocha/mock.rb, line 368 def raise_unexpected_invocation_error(invocation, matching_expectation) if @unexpected_invocation.nil? @unexpected_invocation = invocation matching_expectation.invoke(invocation) if matching_expectation message = "#{@unexpected_invocation.call_description}\n#{@mockery.mocha_inspect}" else message = @unexpected_invocation.short_call_description end raise ExpectationErrorFactory.build("unexpected invocation: #{message}", caller) end