RSpec控制器销毁测试

Question

I'm building a test application that lets user create/delete posts. I'm having a bug in my destroy action that I'm finding difficult to debug. Here's my test:

  describe '#destroy' do
    context 'existing post' do
      let (:post) { FactoryGirl.create(:post) }

      it 'removes post from table' do
        expect { delete :destroy, id: post }.to change { Post.count }.by(-1)
      end

      it 'renders index template' do
        delete :destroy, id: post
        expect(response).to render_template('index')
      end
    end

    context 'delete a non-existent post' do
      it 'creates an error message' do
        delete :destroy, id: 10000
        expect(flash[:errors]).to include("Post doesn't exist")
      end
    end
  end

Here's my destroy action:

  def destroy
    @post = Post.find_by(id: params[:id])
    if @post
      @post.destroy
    else
      flash[:errors] = "Post doesn't exist"
    end
    render :index
  end

I put a debugger in the action, and it looks like the post is found and deleted properly, so I suspect the issue is with the way I'm evaluating the test. Here's my failing spec:

  1) PostsController#destroy existing post removes post from table
     Failure/Error: expect { delete :destroy, id: post }.to change { Post.count }.by(-1)
       expected result to have changed by -1, but was changed by 0

What's going on here?

Answer 1

I think your post is created but after the first count is evaluated. Let's assure it's created before with let!

let!(:post) { FactoryGirl.create(:post) }