instance method `assert_no_difference`

Ruby on Rails 7.0.10

Since v2.3.18

Available in: v2.3.18 v3.0.20 v3.1.12 v3.2.22.5 v4.0.13 v4.1.16 v4.2.9 v5.2.8.1 v6.0.6 v6.1.7.10 v7.0.10 v7.1.6 v7.2.3 v8.0.4 v8.1.2

Compare with:

assert_no_difference(expression, message = nil, &block)

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, params: { article: invalid_attributes }
end

A lambda can be passed in and evaluated.

assert_no_difference -> { Article.count } do
  post :create, params: { article: invalid_attributes }
end

An error message can be specified.

assert_no_difference 'Article.count', 'An Article should not be created' do
  post :create, params: { article: invalid_attributes }
end

An array of expressions can also be passed in and evaluated.

assert_no_difference [ 'Article.count', -> { Post.count } ] do
  post :create, params: { article: invalid_attributes }
end

Parameters

expression req
message opt = nil
block block

Source

# File activesupport/lib/active_support/testing/assertions.rb, line 137
      def assert_no_difference(expression, message = nil, &block)
        assert_difference expression, 0, message, &block
      end

Defined in activesupport/lib/active_support/testing/assertions.rb line 137 · View on GitHub · Improve this page · Find usages on GitHub

Defined in ActiveSupport::Testing::Assertions

Signature

Parameters