Module | ActiveSupport::Testing::Assertions |
In: |
vendor/rails/activesupport/lib/active_support/testing/assertions.rb
|
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
# File vendor/rails/activesupport/lib/active_support/testing/assertions.rb, line 34 34: def assert_difference(expression, difference = 1, message = nil, &block) 35: b = block.send(:binding) 36: exps = Array.wrap(expression) 37: before = exps.map { |e| eval(e, b) } 38: 39: yield 40: 41: exps.each_with_index do |e, i| 42: error = "#{e.inspect} didn't change by #{difference}" 43: error = "#{message}.\n#{error}" if message 44: assert_equal(before[i] + difference, eval(e, b), error) 45: end 46: 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
# File vendor/rails/activesupport/lib/active_support/testing/assertions.rb, line 60 60: def assert_no_difference(expression, message = nil, &block) 61: assert_difference expression, 0, message, &block 62: end