rspec的尴尬语法检测更换计数

Question

我有一个RSpec测试，看起来像这样：

describe 'on DELETE to :destroy' do 
    before do 
    expect { delete :destroy, id: 6 }.to change(ModelName, :count) 
    end 

    it { is_expected.to respond_with :success } 
    it { is_expected.to render_template :destroy } 
end 

我觉得别扭其上更改测试算before块里面，我并不需要运行它两次。我希望能找到一个语法是这样的，而不是：

describe 'on DELETE to :destroy' do 
    before do 
    delete :destroy, id: 6 
    end 

    it { is_expected.to respond_with :success } 
    it { is_expected.to render_template :destroy } 
    it { is_expected.to change(ModelName, :count) } 
end 

但是第三次​​试验给了我以下错误：由于错误信息提示，你需要传递一个块

expected #count to have changed, but was not given a block 

Answer 1

，例如：

it { is_expected.to change { ModelName.count } }