- A
UNTRACKED | = | Object.new |
Assertion that the result of evaluating an expression is changed before and after invoking the passed in block.
assert_changes 'Status.all_good?' do
post :create, params: { status: { ok: false } }
end
You can pass the block as a string to be evaluated in the context of the block. A lambda can be passed for the block as well.
assert_changes -> { Status.all_good? } do
post :create, params: { status: { ok: false } }
end
The assertion is useful to test side effects. The passed block can be anything that can be converted to string with to_s.
assert_changes :@object do
@object = 42
end
The keyword arguments :from and :to can be given to specify the expected initial value and the expected value after the block was executed.
assert_changes :@object, from: nil, to: :foo do
@object = :foo
end
An error message can be specified.
assert_changes -> { Status.all_good? }, 'Expected the status to be bad' do
post :create, params: { status: { incident: true } }
end
# File activesupport/lib/active_support/testing/assertions.rb, line 143 def assert_changes(expression, message = nil, from: UNTRACKED, to: UNTRACKED, &block) exp = expression.respond_to?(:call) ? expression : -> { eval(expression.to_s, block.binding) } before = exp.call retval = yield unless from == UNTRACKED error = "#{expression.inspect} isn't #{from.inspect}" error = "#{message}.\n#{error}" if message assert from === before, error end after = exp.call if to == UNTRACKED error = "#{expression.inspect} didn't changed" error = "#{message}.\n#{error}" if message assert_not_equal before, after, error else error = "#{expression.inspect} didn't change to #{to}" error = "#{message}.\n#{error}" if message assert to === after, error end retval end
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, params: { article: {...} }
end
An arbitrary expression is passed in and evaluated.
assert_difference 'Article.last.comments(:reload).size' do
post :create, params: { comment: {...} }
end
An arbitrary positive or negative difference can be specified. The default
is 1
.
assert_difference 'Article.count', -1 do
post :delete, params: { id: ... }
end
An array of expressions can also be passed in and evaluated.
assert_difference [ 'Article.count', 'Post.count' ], 2 do
post :create, params: { article: {...} }
end
A lambda or a list of lambdas can be passed in and evaluated:
assert_difference ->{ Article.count }, 2 do
post :create, params: { article: {...} }
end
assert_difference [->{ Article.count }, ->{ Post.count }], 2 do
post :create, params: { article: {...} }
end
An error message can be specified.
assert_difference 'Article.count', -1, 'An Article should be destroyed' do
post :delete, params: { id: ... }
end
# File activesupport/lib/active_support/testing/assertions.rb, line 74 def assert_difference(expression, difference = 1, message = nil, &block) expressions = Array(expression) exps = expressions.map { |e| e.respond_to?(:call) ? e : lambda { eval(e, block.binding) } } before = exps.map(&:call) retval = yield expressions.zip(exps).each_with_index do |(code, e), i| error = "#{code.inspect} didn't change by #{difference}" error = "#{message}.\n#{error}" if message assert_equal(before[i] + difference, e.call, error) end retval end
Assertion that the result of evaluating an expression is changed before and after invoking the passed in block.
assert_no_changes 'Status.all_good?' do
post :create, params: { status: { ok: true } }
end
An error message can be specified.
assert_no_changes -> { Status.all_good? }, 'Expected the status to be good' do
post :create, params: { status: { ok: false } }
end
# File activesupport/lib/active_support/testing/assertions.rb, line 182 def assert_no_changes(expression, message = nil, &block) exp = expression.respond_to?(:call) ? expression : -> { eval(expression.to_s, block.binding) } before = exp.call retval = yield after = exp.call error = "#{expression.inspect} did change to #{after}" error = "#{message}.\n#{error}" if message assert_equal before, after, error retval 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, 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
Asserts that an expression is not truthy. Passes if object
is
nil
or false
. “Truthy” means “considered true in
a conditional” like if foo
.
assert_not nil # => true
assert_not false # => true
assert_not 'foo' # => Expected "foo" to be nil or false
An error message can be specified.
assert_not foo, 'foo should be false'
Assertion that the block should not raise an exception.
Passes if evaluated code in the yielded block raises no exception.
assert_nothing_raised do
perform_service(param: 'no_exception')
end