module ActiveSupport module Testing module Assertions # Test numeric difference between the return value of an expression as a result of what is evaluated # in the yielded block. # # assert_difference 'Article.count' do # post :create, :article => {...} # end # # An arbitrary expression is passed in and evaluated. # # assert_difference 'assigns(:article).comments(:reload).size' do # post :create, :comment => {...} # end # # An arbitrary positive or negative difference can be specified. The default is +1. # # assert_difference 'Article.count', -1 do # post :delete, :id => ... # end # # An array of expressions can also be passed in and evaluated. # # assert_difference [ 'Article.count', 'Post.count' ], +2 do # post :create, :article => {...} # end # # A error message can be specified. # # assert_difference 'Article.count', -1, "An Article should be destroyed" do # post :delete, :id => ... # end def assert_difference(expressions, difference = 1, message = nil, &block) expression_evaluations = Array(expressions).collect{ |expression| lambda { eval(expression, block.send(:binding)) } } original_values = expression_evaluations.inject([]) { |memo, expression| memo << expression.call } yield expression_evaluations.each_with_index do |expression, i| assert_equal original_values[i] + difference, expression.call, message end end # Assertion that the numeric result of evaluating an expression is not changed before and after # invoking the passed in block. # # assert_no_difference 'Article.count' do # post :create, :article => invalid_attributes # end # # A error message can be specified. # # assert_no_difference 'Article.count', "An Article should not be destroyed" do # post :create, :article => invalid_attributes # end def assert_no_difference(expressions, message = nil, &block) assert_difference expressions, 0, message, &block end end end end