module Test
  module Unit
    module Given
      # A simple form that doesn't enforce the use of 
      # Given/When/Then.  This is merely to make it clear
      # which parts of your test do what
      module Simple
        # Public: Set up the conditions for the test
        #
        # existing_block - a callable object (e.g. a Proc) that will be called immediately
        #                  by this Given.  If nil, &block is expected to be passed
        # block          - a block given to this call that will be executed immediately
        #                  by this Given.  If existing_block is non-nil, this is ignored
        #
        # Examples
        #     
        #     given_block = Given {
        #       @foo = "bar"
        #     }
        #     # => executes block and returns it
        #     Given given_block
        #     # => executes the block again
        #
        # Returns the block that was executed
        def Given(existing_block=nil,&block)
          call_block_param_or_block_given(existing_block,&block)
        end
        # Public: Execute the code under test
        #
        # existing_block - a callable object (e.g. a Proc) that will be called immediately
        #                  by this When.  If nil, &block is expected to be passed
        # block          - a block given to this call that will be executed immediately
        #                  by this When.  If existing_block is non-nil, this is ignored
        #
        # Examples
        #     
        #     when_block = When {
        #       @foo.go
        #     }
        #     # => executes block and returns it
        #     When when_block
        #     # => executes the block again
        #
        # Returns the block that was executed
        def When(existing_block=nil,&block)
          Given(existing_block,&block)
        end

        # Public: Verify the results of the test
        #
        # existing_block - a callable object (e.g. a Proc) that will be called immediately
        #                  by this Then.  If nil, &block is expected to be passed
        # block          - a block given to this call that will be executed immediately
        #                  by this Then.  If existing_block is non-nil, this is ignored
        #
        # Examples
        #     
        #     then_block = Then {
        #       assert_equal "bar",@foo
        #     }
        #     # => executes block and returns it
        #     Then then_block
        #     # => executes the block again
        #
        # Returns the block that was executed
        def Then(existing_block=nil,&block)
          Given(existing_block,&block)
        end

        # Public: Continue the previous Given/When/Then in a new block.  The reason
        # you might do this is if you wanted to use the existing block form of a
        # Given/When/Then, but also need to do something custom.  This allows you to 
        # write your test more fluently.
        #
        # existing_block - a callable object (e.g. a Proc) that will be called immediately
        #                  by this Then.  If nil, &block is expected to be passed
        # block          - a block given to this call that will be executed immediately
        #                  by this Then.  If existing_block is non-nil, this is ignored
        #
        # Examples
        #     
        #     then_block = Then {
        #       assert_equal "bar",@foo
        #     }
        #     # => executes block and returns it
        #     Then then_block
        #     And {
        #       assert_equal, "quux",@blah
        #     }
        #     # => executes the block again
        #
        # Returns the block that was executed
        def And(existing_block=nil,&block)
          Given(existing_block,&block)
        end

        private

        def call_block_param_or_block_given(existing_block,&block)
          if existing_block.nil?
            block.call
            block
          else
            existing_block.call
            existing_block
          end
        end
      end
    end
  end
end