mock.rb

Ruby/Mock version 1.0

This file contains the Test::Unit::Mockup class, an adapter class for conveniently building mock objects in Test::Unit test cases. It is based on ideas in Ruby/Mock by Nat Pryce <nat.pryce@b13media.com>, which is a class for doing much the same thing for RUnit test cases.

Examples

For the examples below, it is assumed that a hypothetical ‘Adapter’ class is needed to test whatever class is being tested. It has two instance methods in addition to its initializer: read, which takes no arguments and returns data read from the adapted source, and write, which takes a String and writes as much as it can to the adapted destination, returning any that is left over.

  # With the in-place mock-object constructor, you can make an instance of a
  # one-off anonymous test class:
  mockAdapter = Test::Unit::MockObject( Adapter ).new

  # Now set up some return values for the next test:
  mockAdapter.setReturnValues( :read => "",
                               :write => Proc::new {|data| data[-20,20]} )

  # Mandate a certain order to the calls
  mockAdapter.setCallOrder( :read, :read, :read, :write, :read )

  # Now start the mock object recording interactions with it
  mockAdapter.activate

  # Send the adapter to the tested object and run the tests
  testedObject.setAdapter( mockAdapter )
  ...

  # Now check the order of method calls on the mock object against the expected
  # order.
  mockAdapter.verify

If you require more advanced functionality in your mock class, you can also use the anonymous class returned by the Test::Unit::MockObject factory method as the superclass for your own mockup like this:

  # Create a mocked adapter class
  class MockAdapter < Test::Unit::MockObject( Adapter )

      def initialize
          super
          setCallOrder( :read, :read, :read, :write, :read )
      end

      def read( *args )
          @readargs = args
          super # Call the mocked method to record the call
      end

      def write( *args )
          @writeargs = args
          super # Call the mocked method to record the call
      end
  end

Note

All the testing and setup methods in the Test::Unit::Mockup class (the abstract class that new MockObjects inherit from) have two aliases for your convenience:

• Each one has a double-underscore alias so that methods which collide with them from the mocked class don’t obscure them. Eg.,

    mockAdapter.__setCallOrder( :read, :read, :read, :write, :read )
  

  can be used instead of the call from the example above if the Adapter for some reason already has a ‘setCallOrder’ instance method.

• Non-camelCase versions of the methods are also provided. Eg.,

    mockAdapter.set_call_order( :read, :read, :read, :write, :read )
  

  will work, too. Double-underscored and non camelCased aliases are not defined; if anyone complains, I’ll add them.

Rcsid

$Id: mock.rb,v 1.1 2004/03/24 02:40:30 neoneye Exp $

Authors

• Michael Granger <ged@FaerieMUD.org>

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