RSpec:...的未定义方法 `assert_difference'(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

我在Google上搜索了此错误，但没有找到解决方法。
请帮帮我。谢谢 :)

Answer 1

确保在spec/spec_helper.rb中包含AssertDifference:

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

并将断言放在 it块中:

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