vendor/rails/activesupport/lib/active_support/testing/core_ext/test/unit/assertions.rb

   1 require 'test/unit/assertions'
   2 module Test
   3   module Unit
   4     #--
   5     # FIXME: no Proc#binding in Ruby 2, must change this API
   6     #++
   7     module Assertions
   8       # Test numeric difference between the return value of an expression as a result of what is evaluated
   9       # in the yielded block.
  10       #
  11       #   assert_difference 'Article.count' do
  12       #     post :create, :article => {...}
  13       #   end
  14       #
  15       # An arbitrary expression is passed in and evaluated.
  16       #
  17       #   assert_difference 'assigns(:article).comments(:reload).size' do
  18       #     post :create, :comment => {...}
  19       #   end
  20       #
  21       # An arbitrary positive or negative difference can be specified. The default is +1.
  22       #
  23       #   assert_difference 'Article.count', -1 do
  24       #     post :delete, :id => ...
  25       #   end
  26       #
  27       # An array of expressions can also be passed in and evaluated.
  28       #
  29       #   assert_difference [ 'Article.count', 'Post.count' ], +2 do
  30       #     post :create, :article => {...}
  31       #   end
  32       #
  33       # A error message can be specified.
  34       #
  35       #   assert_difference 'Article.count', -1, "An Article should be destroyed" do
  36       #     post :delete, :id => ...
  37       #   end
  38       def assert_difference(expressions, difference = 1, message = nil, &block)
  39         expression_evaluations = Array(expressions).map do |expression|
  40           [expression, lambda do
  41             eval(expression, block.__send__(:binding))
  42           end]
  43         end
  44
  45         original_values = expression_evaluations.inject([]) { |memo, expression| memo << expression[1].call }
  46         yield
  47         expression_evaluations.each_with_index do |expression, i|
  48           full_message = ""
  49           full_message << "#{message}.\n" if message
  50           full_message << "<#{expression[0]}> was the expression that failed"
  51           assert_equal original_values[i] + difference, expression[1].call, full_message
  52         end
  53       end
  54
  55       # Assertion that the numeric result of evaluating an expression is not changed before and after
  56       # invoking the passed in block.
  57       #
  58       #   assert_no_difference 'Article.count' do
  59       #     post :create, :article => invalid_attributes
  60       #   end
  61       #
  62       # A error message can be specified.
  63       #
  64       #   assert_no_difference 'Article.count', "An Article should not be destroyed" do
  65       #     post :create, :article => invalid_attributes
  66       #   end
  67       def assert_no_difference(expressions, message = nil, &block)
  68         assert_difference expressions, 0, message, &block
  69       end
  70     end
  71   end
  72 end