一個測試工程師走進一家酒吧……

原創

2021-06-25 16:28

0，t(i+1)爲對於 t(i)的測試，t(i+1)正確爲 t(i)正確的必要條件，那麼對所有的 i，i>0，t(i)正確都是 t(0)正確的必要條件。。。"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https:\/\/static001.geekbang.org\/infoq\/59\/59926aa33715b243e0541d2e2b60c02d.png","alt":"圖片","title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"測試的種類"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"測試的種類有非常多，我們這裏只挑幾個對一般開發者來說比較重要的測試，做簡略的說明。"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"白盒測試、黑盒測試"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"首先是從測試方法上可以分爲白盒測試和黑盒測試（當然還存在所謂的灰盒測試，這裏不討論）"}]},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"白盒測試 (White-box testing)：白盒測試又稱透明盒測試、結構測試等，軟件測試的主要方法之一，也稱結構測試、邏輯驅動測試或基於程序本身的測試。測試應用程序的內部結構或運作，而不是測試應用程序的功能。在白盒測試時，以編程語言的角度來設計測試案例。測試者輸入數據驗證數據流在程序中的流動路徑，並確定適當的輸出，類似測試電路中的節點。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"黑盒測試 (Black-box testing)：黑盒測試，軟件測試的主要方法之一，也可以稱爲功能測試、數據驅動測試或基於規格說明的測試。測試者不瞭解程序的內部情況，不需具備應用程序的代碼、內部結構和編程語言的專門知識。只知道程序的輸入、輸出和系統的功能，這是從用戶的角度針對軟件界面、功能及外部結構進行測試，而不考慮程序內部邏輯結構。"}]}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我們寫的單元測試一般屬於白盒測試，因爲我們對測試對象的內部邏輯有着充分了解。"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"單元測試、集成測試"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"從測試的維度上，又可以分爲單元測試和集成測試："}]},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在計算機編程中，單元測試又稱爲模塊測試，是針對程序模塊來進行正確性檢驗的測試工作。程序單元是應用的最小可測試部件。在過程化編程中，一個單元就是單個程序、函數、過程等；對於面向對象編程，最小單元就是方法，包括基類、抽象類、或者派生類中的方法。"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"整合測試又稱組裝測試，即對程序模塊採用一次性或增值方式組裝起來，對系統的接口進行正確性檢驗的測試工作。整合測試一般在單元測試之後、系統測試之前進行。實踐表明，有時模塊雖然可以單獨工作，但是並不能保證組裝起來也可以同時工作。"}]}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"單元測試可以是黑盒測試，集成測試亦可以是白盒測試"}]}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"迴歸測試"}]},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"迴歸測試是軟件測試的一種，旨在檢驗軟件原有功能在修改後是否保持完整。"}]}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"迴歸測試主要是希望維持軟件的不變性，我們舉一個例子來說明。例如我們發現軟件在運行的過程中出現了問題，在 gitlab 上開啓了一個 issue。之後我們並且定位到了問題，我們可以先寫一個測試（測試的名稱可以帶上 issue 的 ID）來複現問題（該版本代碼運行此測試結果失敗）。之後我們修復問題後，再次運行測試，測試的結果應當成功。那麼我們之後每次運行測試的時候，通過運行這個測試，可以保證同樣的問題不會復現。"}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"一個基本的測試"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我們先來看一個 Golang 的代碼："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"\/\/ add.go\npackage add\n\nfunc Add(a, b int) int {\n return a + b\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"一個測試用例可以寫成："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"\/\/ add_test.go\npackage add\n\nimport (\n \"testing\"\n)\n\nfunc TestAdd(t *testing.T) {\n res := Add(1, 2)\n if res != 3 {\n t.Errorf(\"the result is %d instead of 3\", res)\n }\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在命令行我們使用 go test"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"go test\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這個時候 go 會執行該目錄下所有的以_test.go 爲後綴中的測試，測試成功的話會有如下輸出："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"% go test\nPASS\nok code.byted.org\/ek\/demo_test\/t01_basic\/correct 0.015s\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"假設這個時候我們把 Add 函數修改成錯誤的實現"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":" \/\/ add.go\npackage add\n\nfunc Add(a, b int) int {\n return a - b\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"再次執行測試命令"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"% go test\n--- FAIL: TestAddWrong (0.00s)\n add_test.go:11: the result is -1 instead of 3\nFAIL\nexit status 1\nFAIL code.byted.org\/ek\/demo_test\/t01_basic\/wrong 0.006s\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"會發現測試失敗。"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"只執行一個測試文件"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"那麼如果我們想只測試這一個文件，輸入"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"go test add_test.go\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"會發現命令行輸出"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"% go test add_test.go\n# command-line-arguments [command-line-arguments.test]\n.\/add_test.go:9:9: undefined: Add\nFAIL command-line-arguments [build failed]\nFAIL\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這是因爲我們沒有附帶測試對象的代碼，修改測試後可以獲得正確的輸出："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"% go test add_test.go add.go\nok command-line-arguments 0.007s\n"}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"測試的幾種書寫方式"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"子測試"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通常來說我們測試某個函數和方法，可能需要測試很多不同的 case 或者邊際條件，例如我們爲上面的 Add 函數寫兩個測試，可以寫成："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":" \/\/ add_test.go\npackage add\n\nimport (\n \"testing\"\n)\n\nfunc TestAdd(t *testing.T) {\n res := Add(1, 0)\n if res != 1 {\n t.Errorf(\"the result is %d instead of 1\", res)\n }\n}\n\nfunc TestAdd2(t *testing.T) {\n res := Add(0, 1)\n if res != 1 {\n t.Errorf(\"the result is %d instead of 1\", res)\n }\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"測試的結果：（使用-v 可以獲得更多輸出）"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"% go test -v\n=== RUN TestAdd\n--- PASS: TestAdd (0.00s)\n=== RUN TestAdd2\n--- PASS: TestAdd2 (0.00s)\nPASS\nok code.byted.org\/ek\/demo_test\/t02_subtest\/non_subtest 0.007s\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"另一種寫法是寫成子測試的形式"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"\/\/ add_test.go\npackage add\n\nimport (\n \"testing\"\n)\n\nfunc TestAdd(t *testing.T) {\n t.Run(\"test1\", func(t *testing.T) {\n res := Add(1, 0)\n if res != 1 {\n t.Errorf(\"the result is %d instead of 1\", res)\n }\n })\n t.Run(\"\", func(t *testing.T) {\n res := Add(0, 1)\n if res != 1 {\n t.Errorf(\"the result is %d instead of 1\", res)\n }\n })\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"執行結果："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"% go test -v\n=== RUN TestAdd\n=== RUN TestAdd\/test1\n=== RUN TestAdd\/#00\n--- PASS: TestAdd (0.00s)\n --- PASS: TestAdd\/test1 (0.00s)\n --- PASS: TestAdd\/#00 (0.00s)\nPASS\nok code.byted.org\/ek\/demo_test\/t02_subtest\/subtest 0.007s\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"可以看到輸出中會將測試按照嵌套的結構分類，子測試的嵌套沒有層數限制，如果不寫測試名的話，會自動按照順序給予序號作爲其測試名（例如上面的#00）"}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"對 IDE（Goland）友好的子測試"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"有一種測試的寫法是："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"tcList := map[string][]int{\n \"t1\": {1, 2, 3},\n \"t2\": {4, 5, 9},\n}\nfor name, tc := range tcList {\n t.Run(name, func(t *testing.T) {\n require.Equal(t, tc[2], Add(tc[0], tc[1]))\n })\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"看上去沒什麼問題，然而有一個缺點是，這個測試對 IDE 並不友好："}]},{"type":"image","attrs":{"src":"https:\/\/static001.geekbang.org\/infoq\/79\/79c622c03b202088a1f8ebaba9a15706.png","alt":"圖片","title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我們無法在出錯的時候對單個測試重新執行所以推薦儘可能對每個 t.Run 都要獨立書寫，例如："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"f := func(a, b, exp int) func(t *testing.T) {\n return func(t *testing.T) {\n require.Equal(t, exp, Add(a, b))\n }\n}\nt.Run(\"t1\", f(1, 2, 3))\nt.Run(\"t2\", f(4, 5, 9))"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https:\/\/static001.geekbang.org\/infoq\/56\/569cad132db865846b91302381f547e5.png","alt":"圖片","title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"測試分包"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我們上面的 add.go 和 add_test.go 文件都處於同一個目錄下，頂部的 package 名稱都是 add，那麼在寫測試的過程中，也可以爲測試啓用與非測試文件不同的包名，例如我們現在將測試文件的包名改爲 add_test："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":" \/\/ add_test.go\npackage add_test\n\nimport (\n \"testing\"\n)\n\nfunc TestAdd(t *testing.T) {\n res := Add(1, 2)\n if res != 3 {\n t.Errorf(\"the result is %d instead of 3\", res)\n }\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這個時候執行 go test 會發現"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"% go test\n# code.byted.org\/ek\/demo_test\/t03_diffpkg_test [code.byted.org\/ek\/demo_test\/t03_diffpkg.test]\n.\/add_test.go:9:9: undefined: Add\nFAIL code.byted.org\/ek\/demo_test\/t03_diffpkg [build failed]\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"由於包名變化了，我們無法再訪問到 Add 函數，這個時候我們增加 import 即可："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":" \/\/ add_test.go\npackage add_test\n\nimport (\n \"testing\"\n\n . \"code.byted.org\/ek\/demo_test\/t03_diffpkg\"\n)\n\nfunc TestAdd(t *testing.T) {\n res := Add(1, 2)\n if res != 3 {\n t.Errorf(\"the result is %d instead of 3\", res)\n }\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我們使用上面的方式來導入包內的函數即可。但使用了這種方式後，將無法訪問包內未導出的函數（以小寫開頭的）。"}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"測試的工具庫"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"github.com\/stretchr\/testify"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我們可以使用強大的 testify 來方便我們寫測試例如上面的測試我們可以用這個庫寫成："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":" \/\/ add_test.go\npackage correct\n\nimport (\n \"testing\"\n\n \"github.com\/stretchr\/testify\/require\"\n)\n\nfunc TestAdd(t *testing.T) {\n res := Add(1, 2)\n require.Equal(t, 3, res)\n\n \/*\n must := require.New(t)\n res := Add(1, 2)\n must.Equal(3, res)\n *\/\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果執行失敗，則會在命令行看到如下輸出："}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"% go test\nok code.byted.org\/ek\/demo_test\/t04_libraries\/testify\/correct 0.008s\n--- FAIL: TestAdd (0.00s)\n add_test.go:12:\n Error Trace: add_test.go:12\n Error: Not equal:\n expected: 3\n actual : -1\n Test: TestAdd\nFAIL\nFAIL code.byted.org\/ek\/demo_test\/t04_libraries\/testify\/wrong 0.009s\nFAIL\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"庫提供了格式化的錯誤詳情（堆棧、錯誤值、期望值等）來方便我們調試。"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"github.com\/DATA-DOG\/go-sqlmock"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"對於需要測試 sql 的地方可以使用 go-sqlmock 來測試"}]},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"優點：不需要依賴數據庫"}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"缺點：脫離了數據庫的具體實現，所以需要寫比較複雜的測試代碼"}]}]}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"github.com\/golang\/mock"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"強大的對 interface 的 mock 庫，例如我們要測試函數 ioutil.ReadAll"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"func ReadAll(r io.Reader) ([]byte, error)\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我們 mock 一個 io.Reader"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"\/\/ package: 輸出包名\n\/\/ destination: 輸出文件\n\/\/ io: mock對象的包\n\/\/ Reader: mock對象的interface名\nmockgen -package gomock -destination mock_test.go io Reader\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"可以在目錄下看到 mock_test.go 文件裏，包含了一個 io.Reader 的 mock 實現我們可以使用這個實現去測試 ioutil.Reader，例如"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"ctrl := gomock.NewController(t)\ndefer ctrl.Finish()\nm := NewMockReader(ctrl)\nm.EXPECT().Read(gomock.Any()).Return(0, errors.New(\"error\"))\n_, err := ioutil.ReadAll(m)\nrequire.Error(t, err)\n"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"net\/http\/httptest"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"通常我們測試服務端代碼的時候，會先啓動服務，再啓動測試。官方的 httptest 包給我們提供了一種方便地啓動一個服務實例來測試的方法。"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"其他"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"其他一些測試工具可以前往 awesome-go#testing 查找"}]},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"https:\/\/github.com\/avelino\/awesome-go#testing"}]}]}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"如何寫好測試"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"上面介紹了測試的基本工具和寫法，我們已經完成了“必先利其器”，下面我們將介紹如何“善其事”。"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"併發測試"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在平時，大家寫服務的時候，基本都必須考慮併發，我們使用 IDE 測試的時候，IDE 默認情況下並不會主動測試併發狀態，那麼如何保證我們寫出來的代碼是併發安全的？我們來舉個例子，比如我們有個計數器，作用就是計數。"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"type Counter int32\n\nfunc (c *Counter) Incr() {\n *c++\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"很顯然這個計數器在併發情況下是不安全的，那麼我們如何寫一個測試來做這個計數器的併發測試呢？"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"import (\n \"sync\"\n \"testing\"\n\n \"github.com\/stretchr\/testify\/require\"\n)\n\nfunc TestA_Incr(t *testing.T) {\n var a Counter\n eg := sync.WaitGroup{}\n count := 10\n eg.Add(count)\n for i := 0; i 0 && j > 0 {\n i += j\n }\n return i\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"下面的測試用例覆蓋率達到了 100%，但是並沒有測試到所有的分支"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"func TestAdd(t *testing.T) {\n res := AddIfBothPositive(1, 2)\n require.Equal(t, 3, res)\n}\n"}]},{"type":"heading","attrs":{"align":null,"level":4},"content":[{"type":"text","text":"並沒有處理異常\/邊界條件"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"func Divide(i, j int) int {\n return i \/ j\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Divide 函數並沒有處理除數爲 0 的情況，而單元測試的覆蓋率是 100%"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"func TestAdd(t *testing.T) {\n res := Divide(6, 2)\n require.Equal(t, 3, res)\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"上面的例子說明 100%的測試覆蓋並不是真的“100%覆蓋”了所有的代碼運行情況。"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"覆蓋率的統計方法"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"測試覆蓋率的統計方法一般是：測試中執行到的代碼行數 \/ 測試的代碼的總行數然而代碼在實際運行中，每一行運行到的概率、出錯的嚴重程度等等也是不同的，所以我們在追求高覆蓋率的同時，不能迷信覆蓋率。"}]},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"測試是不怕重複書寫的"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這裏的重複書寫，可以一定程度上認爲是“代碼複用”的反義詞。我們主要從下面的幾方面來說。"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"重複書寫類似的測試用例"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"測試用例只要不是完全一致，那麼即便是比較雷同的測試用例，我們都可以認爲是有意義的，沒有必要爲了代碼的精簡特地刪除，例如我們測試上面的 Add 函數"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"func TestAdd(t *testing.T) {\n t.Run(\"fixed\", func(t *testing.T) {\n res := Add(1, 2)\n require.Equal(t, 3, res)\n })\n t.Run(\"random\", func(t *testing.T) {\n a := rand.Int()\n b := rand.Int()\n res := Add(a, b)\n require.Equal(t, a+b, res)\n })\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"雖然第二個測試看起來覆蓋了第一個測試，但沒有必要去特地刪除第一個測試，越多的測試越能增加我們代碼的可靠性。"}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"重複書寫（源）代碼中的定義和邏輯"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"比如我們有一份代碼"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"package add\n\nconst Value = 3\n\nfunc AddInternalValue(a int) int {\n return a + Value\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"測試爲"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"func TestAdd(t *testing.T) {\n res := AddInternalValue(1)\n require.Equal(t, 1+Value, res)\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"看起來非常完美，但是如果某天內部變量 Value 的值被不小心改動了，那麼這個測試無法反應出這個改動，也就無法及時發現這個錯誤了。如果我們寫成"}]},{"type":"codeblock","attrs":{"lang":null},"content":[{"type":"text","text":"func TestAdd(t *testing.T) {\n const value = 3\n res := AddInternalValue(1)\n require.Equal(t, 1+value, res)\n}\n"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"就不用擔心無法發現常量值的變化了。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"本文轉載自：字節跳動技術團隊（ID：toutiaotechblog）"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"原文鏈接："},{"type":"link","attrs":{"href":"https:\/\/mp.weixin.qq.com\/s\/9x8wdhDDMn-UBkTPG4SsCg","title":"xxx","type":null},"content":[{"type":"text","text":"一個測試工程師走進一家酒吧……"}]}]}]}