over 8 years ago
Mocking
在這個例子裡面，我們用了 mock 手法，確認 show 這個 action，真的有去呼叫 Suggestion.find
allow(Suggestion).to receive(:find).and_return(suggestion)expect(Suggestion).to receive(:find)
describe "GET show" do
it "assigns @course and render show" do
suggestion = double(:to_param => "123" )
allow(Suggestion).to receive(:find).and_return(suggestion)
expect(Suggestion).to receive(:find)
get :show, :id => suggestion.to_param
expect(response).to render_template :show
expect(assigns[:suggestion]).to eq(suggestion)
end
end
class SuggestionController
def show
@suggestion = Suggestion.find(params[:id])
end
end
劣勢：順序「反直覺」
但是其實這樣的寫法，對於我們之前提到的 Four-Phase Test：
- Setup （準備測試資料）
- Exercie （實際執行測試）
- Verification （驗證測試結果）
- Teardown （拆解測試）
有點相違背了。
我們先做了 Verification （expect）再做 Exercise ( get :show) 。
劣勢：容易失敗
而且在拆解階段，我們會將這段測試重寫成這樣。將 expect 寫在 before 階段，但這樣寫的缺點是，expect 如果不如預期，後面測試會因為 except 全死。
describe "GET show" do
before do
@suggestion = double(:to_param => "123" )
allow(Suggestion).to receive(:find).and_return(@suggestion)
expect(Suggestion).to receive(:find)
get :show, :id => @suggestion.to_param
end
it { expect(response).to render_template :show }
it { expect(assigns[:suggestion]).to eq(@suggestion)}
end
Spying
與其使用 Mocking 手法，我們可以改用 Spy 手法，將測試改成這樣。（RSpec 使用 have_received 去驗證）
describe "GET show" do
before do
@suggestion = double(:to_param => "123" )
allow(Suggestion).to receive(:find).with(@suggestion.to_param).and_return(@suggestion)
get :show, :id => @suggestion.to_param
end
it { expect(response).to render_template :show }
it "should find suggestion and assign suggestion" do
expect(Suggestion).to have_received(:find).with(@suggestion.to_param)
expect(assigns[:suggestion]).to eq(@suggestion)
end
end
Four Phase 順序不但正確，而且是在 Exercise 後，才做 Verification。