assert_no_changes(expression, message = nil, from: UNTRACKED, &block)
public
Assertion that the result of evaluating an expression is not changed before
and after invoking the passed in block.
assert_no_changes 'Status.all_good?' do
post :create, params: { status: { ok: true } }
end
Provide the optional keyword argument :from to specify the
expected initial value.
assert_no_changes -> { Status.all_good? }, from: true 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 252
def assert_no_changes(expression, message = nil, from: UNTRACKED, &block)
exp = expression.respond_to?(:call) ? expression : -> { eval(expression.to_s, block.binding) }
before = exp.call
retval = _assert_nothing_raised_or_warn("assert_no_changes", &block)
unless from == UNTRACKED
rich_message = -> do
error = "Expected initial value of #{from.inspect}, got #{before.inspect}"
error = "#{message}.\n#{error}" if message
error
end
assert from === before, rich_message
end
after = exp.call
rich_message = -> do
code_string = expression.respond_to?(:call) ? _callable_to_source_string(expression) : expression
error = "`#{code_string}` changed"
error = "#{message}.\n#{error}" if message
error
end
if before.nil?
assert_nil after, rich_message
else
assert_equal before, after, rich_message
end
retval
end
