RSpec: Undefined method `assert_difference' for ... (NoMethodError)

Question

context 'with event_type is available create event' do
  let(:event_type) { EventType.where( name: 'visit_site').first }
  assert_difference 'Event.count' do
    Event.fire_event(event_type, @sponge,{})
  end
end

I searched Google for this error but found nothing to fix it. Help me please. Thank you :)

Answer 1

Make sure you include AssertDifference in spec/spec_helper.rb:

RSpec.configure do |config|
  ...   
  config.include AssertDifference
end

And put the assertion inside of an it block:

it 'event count should change' do
  assert_difference 'Event.count' do
    ...
  end
end