Class Mocha::Configuration
In: lib/mocha/configuration.rb
Parent: Object

This class allows you to determine what should happen under certain circumstances. In each scenario, Mocha can be configured to {.allow do nothing}, {.warn_when display a warning message}, or {.prevent raise an exception}. The relevant scenario is identified using one of the following symbols:

  • +:stubbing_method_unnecessarily+ This is useful for identifying unused stubs. Unused stubs are often accidentally introduced when code is {martinfowler.com/bliki/DefinitionOfRefactoring.html refactored}. Allowed by default.
  • +:stubbing_non_existent_method+ - This is useful if you want to ensure that methods you‘re mocking really exist. A common criticism of unit tests with mock objects is that such a test may (incorrectly) pass when an equivalent non-mocking test would (correctly) fail. While you should always have some integration tests, particularly for critical business functionality, this Mocha configuration setting should catch scenarios when mocked methods and real methods have become misaligned. Allowed by default.
  • +:stubbing_non_public_method+ - Many people think that it‘s good practice only to mock public methods. This is one way to prevent your tests being too tightly coupled to the internal implementation of a class. Such tests tend to be very brittle and not much use when refactoring. Allowed by default.
  • +:stubbing_method_on_non_mock_object+ - If you like the idea of {www.jmock.org/oopsla2004.pdf mocking roles not objects} and {www.mockobjects.com/2007/04/test-smell-mocking-concrete-classes.html you don‘t like stubbing concrete classes}, this is the setting for you. However, while this restriction makes a lot of sense in Java with its {java.sun.com/docs/books/tutorial/java/concepts/interface.html explicit interfaces}, it may be moot in Ruby where roles are probably best represented as Modules. Allowed by default.
  • +:stubbing_method_on_nil+ - This is usually done accidentally, but there might be rare cases where it is intended. Prevented by default.

@example Preventing unnecessary stubbing of a method

  Mocha::Configuration.prevent(:stubbing_method_unnecessarily)

  example = mock('example')
  example.stubs(:unused_stub)
  # => Mocha::StubbingError: stubbing method unnecessarily:
  # =>   #<Mock:example>.unused_stub(any_parameters)

@example Preventing stubbing of a method on a non-mock object

  Mocha::Configuration.prevent(:stubbing_method_on_non_mock_object)

  class Example
    def example_method; end
  end

  example = Example.new
  example.stubs(:example_method)
  # => Mocha::StubbingError: stubbing method on non-mock object:
  # =>   #<Example:0x593620>.example_method

@example Preventing stubbing of a non-existent method

  Mocha::Configuration.prevent(:stubbing_non_existent_method)

  class Example
  end

  example = Example.new
  example.stubs(:method_that_doesnt_exist)
  # => Mocha::StubbingError: stubbing non-existent method:
  # =>   #<Example:0x593760>.method_that_doesnt_exist

@example Preventing stubbing of a non-public method

  Mocha::Configuration.prevent(:stubbing_non_public_method)

  class Example
    def internal_method; end
    private :internal_method
  end

  example = Example.new
  example.stubs(:internal_method)
  # => Mocha::StubbingError: stubbing non-public method:
  # =>   #<Example:0x593530>.internal_method

Typically the configuration would be set globally in a +test_helper.rb+ or +spec_helper.rb+ file. However, it can also be temporarily overridden locally using the block syntax of the relevant method. In the latter case, the original configuration settings are restored when the block is exited.

@example Temporarily allowing stubbing of a non-existent method

  Mocha::Configuration.prevent(:stubbing_non_public_method)

  class Example
  end

  Mocha::Configuration.allow(:stubbing_non_existent_method) do
    example = Example.new
    example.stubs(:method_that_doesnt_exist)
    # => no exception raised
  end

Methods

Constants

DEFAULTS = { :stubbing_method_unnecessarily => :allow, :stubbing_method_on_non_mock_object => :allow, :stubbing_non_existent_method => :allow, :stubbing_non_public_method => :allow, :stubbing_method_on_nil => :prevent

Public Class methods

Allow the specified action.

@param [Symbol] action one of +:stubbing_method_unnecessarily+, +:stubbing_method_on_non_mock_object+, +:stubbing_non_existent_method+, +:stubbing_non_public_method+, +:stubbing_method_on_nil+. @yield optional block during which the configuration change will be changed before being returned to its original value at the end of the block.

Raise a {StubbingError} if if the specified action is attempted.

@param [Symbol] action one of +:stubbing_method_unnecessarily+, +:stubbing_method_on_non_mock_object+, +:stubbing_non_existent_method+, +:stubbing_non_public_method+, +:stubbing_method_on_nil+. @yield optional block during which the configuration change will be changed before being returned to its original value at the end of the block.

Warn if the specified action is attempted.

@param [Symbol] action one of +:stubbing_method_unnecessarily+, +:stubbing_method_on_non_mock_object+, +:stubbing_non_existent_method+, +:stubbing_non_public_method+, +:stubbing_method_on_nil+. @yield optional block during which the configuration change will be changed before being returned to its original value at the end of the block.

[Validate]