Module: Test::Unit::Assertions

Defined in:
lib/active_support/testing/core_ext/test/unit/assertions.rb

Overview

– FIXME: no Proc#binding in Ruby 2, must change this API ++

Instance Method Summary collapse

Instance Method Details

#assert_difference(expressions, difference = 1, message = nil, &block) ⇒ Object

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



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# File 'lib/active_support/testing/core_ext/test/unit/assertions.rb', line 38

def assert_difference(expressions, difference = 1, message = nil, &block)
  expression_evaluations = Array(expressions).map do |expression|
    [expression, lambda do
      eval(expression, block.__send__(:binding))
    end]
  end

  original_values = expression_evaluations.inject([]) { |memo, expression| memo << expression[1].call }
  yield
  expression_evaluations.each_with_index do |expression, i|
    full_message = ""
    full_message << "#{message}.\n" if message
    full_message << "<#{expression[0]}> was the expression that failed"
    assert_equal original_values[i] + difference, expression[1].call, full_message
  end
end

#assert_no_difference(expressions, message = nil, &block) ⇒ Object

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



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# File 'lib/active_support/testing/core_ext/test/unit/assertions.rb', line 67

def assert_no_difference(expressions, message = nil, &block)
  assert_difference expressions, 0, message, &block
end