做為軟件開發工程師一定要懂測試. 你不懂你的全局觀還不夠. 架構師需要理解測試. 你不懂測試你不會理解測試過程痛, 不能友好的與測試工程師協作. 你不測試說明你的LEVEL還不夠高, 對於軟件質量理解還不夠. 遠的測試過程不說, 先說說單元測試UT. 很多開發工程師, 什麽高大上微服務項目都做過了, 還是寫不好單元測試. 單元測試這是一個普通的技能了. 你寫不好, 說明你不專業. 閱讀以下內容讓我們專業點兒:

一. 測試的價值

Tests help us catch mistakes. Tests help us shape our design to actual use.

註意詞Shape, 再者是

Tests help us avoid gold-plating by being explicit about what the required behavior is.

很多測試因素直接或間接影響 產出效率, 如下圖

測試也是個設計工具, 叠代的思想:

TDD思想出來了, 循環叠代, 有時候與我們做成一件事過程也是相同的.

二. 測試不要依賴真實數據庫
使用內存數據庫, 如下的實踐

• Substitute test doubles for third-party library dependencies, wrapping them with your own adapters where necessary. The tricky stuff is then encapsulated inside those adapters that you can test separately from the rest of application logic. ?
• Keep test code and the resources they use together, perhaps in the same package. ?
• Let test code produce the resources it needs rather than keeping them separate from the source code. ?
• Have your tests set up the context they need. Don’t rely on any other tests being run before the one you’re writing. ?
• Use an in-memory database for integration tests that require persistence, as it greatly simplifies the problem of starting tests with a clean data set. Plus, they’re generally superfast to boot up. ?
• Split threaded code into asynchronous and synchronous halves, with all application logic in a regular, synchronous unit of code that you can easily test without complications, leaving the tricky concurrency stuff to a small, dedicated group of tests.

我們在Test double 概念中也看到 Fake 對象提及 內存數據庫

• Dummy objects are passed around but never actually used. Usually they are just used to fill parameter lists.
• Fake objects actually have working implementations, but usually take some shortcut which makes them not suitable for production (an InMemoryTestDatabase is a good example).
• Stubs provide canned answers to calls made during the test, usually not responding at all to anything outside what‘s programmed in for the test.
• Spies are stubs that also record some information based on how they were called. One form of this might be an email service that records how many messages it was sent.
• Mocks are pre-programmed with expectations which form a specification of the calls they are expected to receive. They can throw an exception if they receive a call they don‘t expect and are checked during verification to ensure they got all the calls they were expecting.

還有一句有意思話

Friends Don‘t Let Friends Hit The Database In Tests

其它BLOG, 還有

Lightweight, drop-in replacement for the database

Aside from substituting a test double for your data access object, the next best thing might be to use a lightweight replacement for your database. For instance, if your persistence layer is built on an ORM framework and you don’t need to hand-craft SQL statements, it likely doesn’t make much of a difference whether the underlying database product is an Oracle, MySQL, or PostgreSQL. In fact, most likely you should be able to swap in something much more lightweight an in-memory, in-process database such as HyperSQL (also known as HSQLDB). The key advantage of an in-memory, in-process database is that such a lightweight alter native conveniently avoids the slowest links in the persistence chain the network calls and the file access.

So far you’ve learned that unit tests should stay away from the network interface and the filesystem if execution speed is a factor. File I/O isn’t exclusive to database.

Separate Dependencies Where Possible. 盡可能隔離依賴

-- from <<Test-Driving JavaScript Applications >>
等以上這些都表達不要依賴數據庫等外部資源. 筆者在某中型公司框架中還看到誤人子弟的單元測試示例,連接了數據庫, 那已經不是單元測試, 已變為集成測試.

三. Arrange-act-assert 結構

良好的結構是好的開端

四. 一些原則

我們原則有 “測試驅動模塊化設計”

“SOLID原則”

代碼可測試性原則:

避免復雜private方法
避免final方法
避免static方法
使用new時小心
避免邏輯在構造函數中
避免Singleton
優先組合而不繼承
包裝外部組件

總結

理解測試, 是我們需要敏捷軟件開發過程基礎. 做為一個軟件開發工程師你需要比任何一個人都關註質量. 你不能總想著有人幫你測試. 相反是你對你的程序復雜找出BUG修正在正在交給其他人前. 原因很簡單, 開發軟件總有BUG, 修復BUG是昂貴的. 上升高度, 你的產出影響了其他人, 如何提高你的影響力.

今天先到這兒，希望對您技術領導力， 企業管理，物聯網, 系統架構設計與評估，團隊管理, 項目管理, 產品管理,團隊建設 有參考作用 , 您可能感興趣的文章:
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作者：Petter Liu
出處：http://www.cnblogs.com/wintersun/
本文版權歸作者和博客園共有，歡迎轉載，但未經作者同意必須保留此段聲明，且在文章頁面明顯位置給出原文連接，否則保留追究法律責任的權利。 該文章也同時發布在我的獨立博客中-Petter Liu Blog。

軟件工程師為什麽要懂測試