assert_difference(expression, difference = 1, message = nil, &block)
Instance Public methods
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