method

assert_no_changes

rails latest stable - Class: ActiveSupport::Testing::Assertions

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 238
      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
          error = "Expected initial value of #{from.inspect}"
          error = "#{message}.\n#{error}" if message
          assert from === before, error
        end

        after = exp.call

        error = "#{expression.inspect} changed"
        error = "#{message}.\n#{error}" if message

        if before.nil?
          assert_nil after, error
        else
          assert_equal before, after, error
        end

        retval
      end

assert_no_changes

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