Class: Mocha::Configuration

Inherits:
Object
  • Object
show all
Defined in:
lib/mocha/configuration.rb

Overview

This class provides a number of ways to configure the library.

Typically the configuration is set globally in a test_helper.rb or spec_helper.rb file.

Examples:

Setting multiple configuration options

Mocha.configure do |c|
  c.stubbing_method_unnecessarily = :prevent
  c.stubbing_method_on_non_mock_object = :warn
  c.stubbing_method_on_nil = :allow
end

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.override(temporary_options) { ... } ⇒ Object

Temporarily modify Mocha::Configuration options.

The supplied temporary_options will override the current configuration for the duration of the supplied block. The configuration will be returned to its original state when the block returns.

Examples:

Temporarily allow stubbing of nil

Mocha::Configuration.override(stubbing_method_on_nil: :allow) do
  nil.stubs(:foo)
end

Parameters:

  • temporary_options (Hash) —

    the configuration options to apply for the duration of the block.

Yields:

  • block during which the configuration change will be in force.



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# File 'lib/mocha/configuration.rb', line 318

def override(temporary_options)
  original_configuration = configuration
  @configuration = configuration.merge(new(temporary_options))
  yield
ensure
  @configuration = original_configuration
end

Instance Method Details

#display_matching_invocations_on_failure=(value) ⇒ Object

Display matching invocations alongside expectations on Mocha-related test failure.

Examples:

Enable display of matching invocations

Mocha.configure do |c|
  c.display_matching_invocations_on_failure = true
end

foo = mock('foo')
foo.expects(:bar)
foo.stubs(:baz).returns('baz').raises(RuntimeError).throws(:tag, 'value')

foo.baz(1, 2)
assert_raises(RuntimeError) { foo.baz(3, 4) }
assert_throws(:tag) { foo.baz(5, 6) }

not all expectations were satisfied
unsatisfied expectations:
- expected exactly once, invoked never: #<Mock:foo>.bar
satisfied expectations:
- allowed any number of times, invoked 3 times: #<Mock:foo>.baz(any_parameters)
  - #<Mock:foo>.baz(1, 2) # => "baz"
  - #<Mock:foo>.baz(3, 4) # => raised RuntimeError
  - #<Mock:foo>.baz(5, 6) # => threw (:tag, "value")

Parameters:

  • value (Boolean) —

    true to enable display of matching invocations; disabled by default.



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# File 'lib/mocha/configuration.rb', line 244

def display_matching_invocations_on_failure=(value)
  @options[:display_matching_invocations_on_failure] = value
end

#strict_keyword_argument_matching=(value) ⇒ Object

Perform strict keyword argument comparison. Only supported in Ruby >= v2.7.

When this option is set to false a positional Hash and a set of keyword arguments are treated the same during comparison, which can lead to misleading passing tests in Ruby >= v3.0 (see examples below). However, a deprecation warning will be displayed if a positional Hash matches a set of keyword arguments or vice versa. This is because #strict_keyword_argument_matching= will default to true in the future.

For more details on keyword arguments in Ruby v3, refer to this article.

Note that Hash-related matchers such as ParameterMatchers#has_value or ParameterMatchers#has_key will still treat a positional Hash and a set of keyword arguments the same, so misleading passing tests are still possible when they are used.

This configuration option is false by default to enable gradual adoption, but will be true by default in the future.

Examples:

Loose keyword argument matching (default)


class Example
  def foo(a, bar:); end
end

example = Example.new
example.expects(:foo).with('a', bar: 'b')
example.foo('a', { bar: 'b' })
# This passes the test, but would result in an ArgumentError in practice

Strict keyword argument matching


Mocha.configure do |c|
  c.strict_keyword_argument_matching = true
end

class Example
  def foo(a, bar:); end
end

example = Example.new
example.expects(:foo).with('a', bar: 'b')
example.foo('a', { bar: 'b' })
# This now fails as expected

Parameters:

  • value (Boolean) —

    true to enable strict keyword argument matching; false by default.



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# File 'lib/mocha/configuration.rb', line 290

def strict_keyword_argument_matching=(value)
  raise 'Strict keyword argument matching requires Ruby 2.7 and above.' unless Mocha::RUBY_V27_PLUS
  @options[:strict_keyword_argument_matching] = value
end

#stubbing_method_on_nil=(value) ⇒ Object

Configure whether stubbing methods on the nil object is allowed.

This is usually done accidentally, but there might be rare cases where it is intended.

This option only works for Ruby < v2.2.0. In later versions of Ruby nil is frozen and so a StubbingError will be raised if you attempt to stub a method on nil.

When value is :allow, do nothing. When value is :warn, display a warning. When value is :prevent, raise a StubbingError. This is the default.

Parameters:

  • value (Symbol) —

    one of :allow, :warn, :prevent.



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# File 'lib/mocha/configuration.rb', line 210

def stubbing_method_on_nil=(value)
  @options[:stubbing_method_on_nil] = value
end

#stubbing_method_on_non_mock_object=(value) ⇒ Object

Configure whether stubbing methods on non-mock objects is allowed.

If you like the idea of mocking roles not objects and 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 explicit interfaces, it may be moot in Ruby where roles are probably best represented as Modules.

When value is :allow, do nothing. This is the default. When value is :warn, display a warning. When value is :prevent, raise a StubbingError.

Examples:

Preventing stubbing of a method on a non-mock object

Mocha.configure do |c|
  c.stubbing_method_on_non_mock_object = :prevent
end

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

Parameters:

  • value (Symbol) —

    one of :allow, :warn, :prevent.



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# File 'lib/mocha/configuration.rb', line 122

def stubbing_method_on_non_mock_object=(value)
  @options[:stubbing_method_on_non_mock_object] = value
end

#stubbing_method_unnecessarily=(value) ⇒ Object

Configure whether stubbing methods unnecessarily is allowed.

This is useful for identifying unused stubs. Unused stubs are often accidentally introduced when code is refactored.

When value is :allow, do nothing. This is the default. When value is :warn, display a warning. When value is :prevent, raise a StubbingError.

Examples:

Preventing unnecessary stubbing of a method

Mocha.configure do |c|
  c.stubbing_method_unnecessarily = :prevent
end

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

Parameters:

  • value (Symbol) —

    one of :allow, :warn, :prevent.



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# File 'lib/mocha/configuration.rb', line 89

def stubbing_method_unnecessarily=(value)
  @options[:stubbing_method_unnecessarily] = value
end

#stubbing_non_existent_method=(value) ⇒ Object

Configure whether stubbing of non-existent methods is allowed.

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.

When value is :allow, do nothing. This is the default. When value is :warn, display a warning. When value is :prevent, raise a StubbingError.

Examples:

Preventing stubbing of a non-existent method


Mocha.configure do |c|
  c.stubbing_non_existent_method = :prevent
end

class Example
end

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

Parameters:

  • value (Symbol) —

    one of :allow, :warn, :prevent.



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# File 'lib/mocha/configuration.rb', line 155

def stubbing_non_existent_method=(value)
  @options[:stubbing_non_existent_method] = value
end

#stubbing_non_public_method=(value) ⇒ Object

Configure whether stubbing of non-public methods is allowed.

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.

When value is :allow, do nothing. This is the default. When value is :warn, display a warning. When value is :prevent, raise a StubbingError.

Examples:

Preventing stubbing of a non-public method

Mocha.configure do |c|
  c.stubbing_non_public_method = :prevent
end

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

Parameters:

  • value (Symbol) —

    one of :allow, :warn, :prevent.



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# File 'lib/mocha/configuration.rb', line 189

def stubbing_non_public_method=(value)
  @options[:stubbing_non_public_method] = value
end