# `unittest` --- 單元測試框架

源代码： Lib/unittest/__init__.py

（假如你已經熟悉相關基礎的測試概念，你可能會希望跳過以下段落，直接參考 assert 方法清單。）

`unittest` 原生的單元測試框架最初由 JUnit 開發，和其他程式語言相似有主要的單元測試框架。支援自動化測試，對測試分享安裝與關閉程式碼，集合所有匯總的測試，並且獨立各個測試報告框架。

`unittest` 用來作為實現支援一些重要的物件導向方法的概念。

test fixture

  test fixture 表示为了开展一项或多项测试所需要进行的准备工作，以及所有相关的清理操作。举个例子，这可能包含创建临时或代理的数据库、目录，再或者启动一个服务器进程。

test case（測試用例）

  一個 test case 是一個獨立的單元測試。這是用來確認一個特定設定的輸入的特殊回饋。 `unittest` 提供一個基礎類別，類別 `TestCase`，可以用來建立一個新的測試條例。

test suite（測試套件）

  test suite 是一個搜集測試條例，測試套件，或是兩者皆有。它需要一起被執行並用來匯總測試。

test runner（測試執行器）

  test runner 是一個編排測試執行與提供結果給使用者的一個元件。執行器可以使用圖形化介面，文字介面或是回傳一個特別值用來標示出執行測試的結果。

也參考

`doctest` 模組

  另一個執行測試的模組，但使用不一樣的測試方法與規範。

Simple Smalltalk Testing: With Patterns

  Kent Beck 的原始論文討論使用 `unittest` 這樣模式的測試框架。

pytest

  第三方单元测试框架，提供轻量化的语法来编写测试，例如：`assert func(10) == 42`。

The Python Testing Tools Taxonomy

  一份詳細的 Python 測試工具列表，包含 functional testing 框架和mock object 函式庫。

Testing in Python Mailing List

  一個專門興趣的群組用來討論 Python 中的測試方式與測試工具。

随 Python 源代码分发的脚本 `Tools/unittestgui/unittestgui.py` 是一个一个用于发现和执行测试的用户图形界面工具。这主要是为了方便新手使用单元测试制作的。在生产环境中，测试应由一个持续集成（CI）系统运行，如 Buildbot, Jenkins ，Travis-CI, 或 AppVeyor。

## 簡單範例

`unittest` 模組提供一系列豐富的工具用來建構與執行測試。本節將展示這一系列工具中一部份，它們已能滿足大部份使用者需求。

這是一段簡短的腳本用來測試 3 個字串方法：

    import unittest

    class TestStringMethods(unittest.TestCase):

        def test_upper(self):
            self.assertEqual('foo'.upper(), 'FOO')

        def test_isupper(self):
            self.assertTrue('FOO'.isupper())
            self.assertFalse('Foo'.isupper())

        def test_split(self):
            s = 'hello world'
            self.assertEqual(s.split(), ['hello', 'world'])
            # check that s.split fails when the separator is not a string
            with self.assertRaises(TypeError):
                s.split(2)

    if __name__ == '__main__':
        unittest.main()

測試用例 (testcase) 可以透過繼承 `unittest.TestCase` 類別來建立。這裡定義了三個獨立的物件方法，名稱皆以 `test` 開頭。這樣的命名方式能告知 test runner 哪些物件方法為定義的測試。

每個測試的關鍵為呼叫 `assertEqual()` 來確認是否為期望的結果； `assertTrue()` 或是 `assertFalse()` 用來驗證一個條件式； `assertRaises()` 用來驗證是否觸發一個特定的 exception。使用這些物件方法來取代 `assert` 陳述句，將能使 test runner 收集所有的測試結果並產生一個報表。

通过 `setUp()` 和 `tearDown()` 方法，可以设置测试开始前与完成后需要执行的指令。 在 组织你的测试代码 中，对此有更为详细的描述。

最後將顯示一個簡單的方法去執行測試 `unittest.main()` 提供一個命令執行列介面測試腳本。當透過命令執行列執行，輸出結果將會像是：

    ...
    ----------------------------------------------------------------------
    Ran 3 tests in 0.000s

    OK

在測試時加入 `-v` 選項將指示 `unittest.main()` 提高 verbosity 層級，產生以下的輸出：

    test_isupper (__main__.TestStringMethods) ... ok
    test_split (__main__.TestStringMethods) ... ok
    test_upper (__main__.TestStringMethods) ... ok

    ----------------------------------------------------------------------
    Ran 3 tests in 0.001s

    OK

以上的例子顯示大多數使用 `unittest` 特徵足以滿足大多數日常測試的需求。接下來第一部分文件的剩餘部分將繼續探索完整特徵設定。

## 命令執行列介面 (Command-Line Interface)

單元測試模組可以透過命令執行列執行測試模組，物件甚至個別的測試方法：

    python -m unittest test_module1 test_module2
    python -m unittest test_module.TestClass
    python -m unittest test_module.TestClass.test_method

你可以通過一個串列與任何模組名稱的組合，完全符合類別與方法的名稱。

測試模組可以根據檔案路徑指定：

    python -m unittest tests/test_something.py

這允許你使用 shell 檔案名稱補完功能 (filename completion) 來指定測試模組。給定的檔案路徑必須亦能被當作模組 import。此路徑轉換為模組名稱的方式為移除 '.py' 並將路徑分隔符 (path separator) 轉換成 '.'。 假如你的測試檔案無法被 import 成模組，你應該直接執行該測試檔案。

通過增加 -v 的旗標數，可以在你執行測試時得到更多細節（更高的 verbosity）：

    python -m unittest -v test_module

若執行時不代任何引數，將執行 Test Discovery（測試探索）：

    python -m unittest

列出所有命令列選項：

    python -m unittest -h

3.2 版更變: 在早期的版本可以個別執行測試方法和不需要模組或是類別。

### 命令列模式選項

unittest supports these command-line options:

`-b````,` `--buffer```

  Standard output 與 standard error stream 將在測試執行被緩衝 (buffer)。這些輸出在測試通過時被丟棄。若是測試錯誤或失則，這些輸出將會正常地被印出，並且被加入至錯誤訊息中。

`-c````,` `--catch```

  `Control-C` 測試執行過程中等待正確的測試結果並回報目前為止所有的測試結果。第二個 `Control-C` 拋出一般例外 `KeyboardInterrupt`。

  參照 Signal Handling 針對函式提供的功能。

`-f````,` `--failfast```

  在第一次錯誤或是失敗停止執行測試。

`-k```

  Only run test methods and classes that match the pattern or substring. This option may be used multiple times, in which case all test cases that match any of the given patterns are included.

  包含通配符（*）的模式使用 `fnmatch.fnmatchcase()` 对测试名称进行匹配。另外，该匹配是大小写敏感的。

  模式对测试加载器导入的测试方法全名进行匹配。

  例如，`-k foo` 可以匹配到 `foo_tests.SomeTest.test_something` 和 `bar_tests.SomeTest.test_foo` ，但是不能匹配到 `bar_tests.FooTest.test_something` 。

`--locals```

  透過 traceback 顯示本地變數。

3.2 版新加入: 增加命令列模式選項 `-b` 、 `-c` 與 `-f`。

3.5 版新加入: 命令列選項 `--locals`。

3.7 版新加入: 命令行选项 `-k` 。

對執行所有的專案或是一個子集合測試，命令列模式可以可以被用來做測試探索。

## Test Discovery（測試探索）

3.2 版新加入.

單元測試支援簡單的 test discovery（測試探索）。為了相容於測試探索，所有的測試檔案都要是模組或是套件（包含 namespace packages），並能從專案的最上層目錄中 import（代表它們的檔案名稱必須是有效的 identifiers）。

Test discovery（測試探索）實作在 `TestLoader.discover()`，但也可以被用於命令列模式。基本的命令列模式用法如下：

    cd project_directory
    python -m unittest discover

備註

`python -m unittest` 作為捷徑，其功能相當於 `python -m unittest discover`。假如你想傳遞引數至探索測試的話，一定要明確地加入 `discover` 子指令。

`discover` 子指令有以下幾個選項：

`-v````,` `--verbose```

  詳細（verbose）輸出

`-s````,` `--start-directory` `directory`

  開始尋找的資料夾（預設為 `.`）

`-p````,` `--pattern` `pattern`

  匹配測試檔案的模式（預設為 `test*.py`）

`-t````,` `--top-level-directory` `directory`

  專案的最高階層目錄 (defaults to start directory)

`-s`, `-p`, 和 `-t` 選項依照傳遞位置作為引數排序順序。以下兩個命令列被視為等價:

    python -m unittest discover -s project_directory -p "*_test.py"
    python -m unittest discover project_directory "*_test.py"

正如可以传入路径那样，传入一个包名作为起始目录也是可行的，如 `myproject.subpackage.test` 。你提供的包名会被导入，它在文件系统中的位置会被作为起始目录。

警示

探索性测试通过导入测试对测试进行加载。在找到所有你指定的开始目录下的所有测试文件后，它把路径转换为包名并进行导入。如 `foo/bar/baz.py` 会被导入为 `foo.bar.baz` 。

如果你有一个全局安装的包，并尝试对这个包的副本进行探索性测试，可能会从错误的地方开始导入。如果出现这种情况，测试会输出警告并退出。

如果你使用包名而不是路径作为开始目录，搜索时会假定它导入的是你想要的目录，所以你不会收到警告。

测试模块和包可以通过 load_tests protocol 自定义测试的加载和搜索。

3.4 版更變: 测试发现支持初始目录下的 命名空间包。注意你也需要指定顶层目录（例如：`python -m unittest discover -s root/namespace -t root`）。

## 组织你的测试代码

单元测试的构建单位是 test cases ：独立的、包含执行条件与正确性检查的方案。在 `unittest` 中，测试用例表示为 `unittest.TestCase` 的实例。通过编写 `TestCase` 的子类或使用 `FunctionTestCase` 编写你自己的测试用例。

一个 `TestCase` 实例的测试代码必须是完全自含的，因此它可以独立运行，或与其它任意组合任意数量的测试用例一起运行。

`TestCase` 的最简单的子类需要实现一个测试方法（例如一个命名以 `test` 开头的方法）以执行特定的测试代码：

    import unittest

    class DefaultWidgetSizeTestCase(unittest.TestCase):
        def test_default_widget_size(self):
            widget = Widget('The widget')
            self.assertEqual(widget.size(), (50, 50))

可以看到，为了进行测试，我们使用了基类 `TestCase` 提供的其中一个 `assert*()` 方法。若测试不通过，将会引发一个带有说明信息的异常，并且 `unittest` 会将这个测试用例标记为测试不通过。任何其它类型的异常将会被当做错误处理。

可能同时存在多个前置操作相同的测试，我们可以把测试的前置操作从测试代码中拆解出来，并实现测试前置方法 `setUp()` 。在运行测试时，测试框架会自动地为每个单独测试调用前置方法。

    import unittest

    class WidgetTestCase(unittest.TestCase):
        def setUp(self):
            self.widget = Widget('The widget')

        def test_default_widget_size(self):
            self.assertEqual(self.widget.size(), (50,50),
                             'incorrect default size')

        def test_widget_resize(self):
            self.widget.resize(100,150)
            self.assertEqual(self.widget.size(), (100,150),
                             'wrong size after resize')

備註

多个测试运行的顺序由内置字符串排序方法对测试名进行排序的结果决定。

在测试运行时，若 `setUp()` 方法引发异常，测试框架会认为测试发生了错误，因此测试方法不会被运行。

相似的，我们提供了一个 `tearDown()` 方法在测试方法运行后进行清理工作。

    import unittest

    class WidgetTestCase(unittest.TestCase):
        def setUp(self):
            self.widget = Widget('The widget')

        def tearDown(self):
            self.widget.dispose()

若 `setUp()` 成功运行，无论测试方法是否成功，都会运行 `tearDown()` 。

这样的一个测试代码运行的环境被称为 test fixture 。一个新的 TestCase 实例作为一个测试脚手架，用于运行各个独立的测试方法。在运行每个测试时，`setUp()` 、`tearDown()` 和 `__init__()` 会被调用一次。

推荐你根据用例所测试的功能将测试用 TestCase 分组。`unittest` 为此提供了 test suite：`unittest` 的 `TestSuite` 类是一个代表。通常情况下，调用 `unittest.main()` 就能正确地找到并执行这个模块下所有用 TestCase 分组的测试。

然而，如果你需要自定义你的测试套件的话，你可以参考以下方法组织你的测试：

    def suite():
        suite = unittest.TestSuite()
        suite.addTest(WidgetTestCase('test_default_widget_size'))
        suite.addTest(WidgetTestCase('test_widget_resize'))
        return suite

    if __name__ == '__main__':
        runner = unittest.TextTestRunner()
        runner.run(suite())

你可以把测试用例和测试套件放在与被测试代码相同的模块中（比如 `widget.py`），但将测试代码放在单独的模块中（比如 `test_widget.py`）有几个优势。

- 测试模块可以从命令行被独立调用。

- 更容易在分发的代码中剥离测试代码。

- 降低没有好理由的情况下修改测试代码以通过测试的诱惑。

- 测试代码应比被测试代码更少地被修改。

- 被测试代码可以更容易地被重构。

- 对用 C 语言写成的模块无论如何都得单独写成一个模块，为什么不保持一致呢？

- 如果测试策略发生了改变，没有必要修改源代码。

## 复用已有的测试代码

一些用户希望直接使用 `unittest` 运行已有的测试代码，而不需要把已有的每个测试函数转化为一个 `TestCase` 的子类。

因此， `unittest` 提供 `FunctionTestCase` 类。这个 `TestCase` 的子类可用于打包已有的测试函数，并支持设置前置与后置函数。

假定有一个测试函数：

    def testSomething():
        something = makeSomething()
        assert something.name is not None
        # ...

可以创建等价的测试用例如下，其中前置和后置方法是可选的。

    testcase = unittest.FunctionTestCase(testSomething,
                                         setUp=makeSomethingDB,
                                         tearDown=deleteSomethingDB)

備註

用 `FunctionTestCase` 可以快速将现有的测试转换成基于 `unittest` 的测试，但不推荐你这样做。花点时间继承 `TestCase` 会让以后重构测试无比轻松。

在某些情况下，现有的测试可能是用 `doctest` 模块编写的。 如果是这样， `doctest` 提供了一个 `DocTestSuite` 类，可以从现有基于 `doctest` 的测试中自动构建 `unittest.TestSuite` 用例。

## 跳过测试与预计的失败

3.1 版新加入.

Unittest 支持跳过单个或整组的测试用例。它还支持把测试标注成“预期失败”的测试，这些坏测试会失败，但不会算进 `TestResult` 的失败里。

要跳过测试只需使用 `skip()` decorator 或其附带条件的版本，在 `setUp()` 内部使用 `TestCase.skipTest()`，或是直接引发 `SkipTest`。

跳过测试的基本用法如下:

    class MyTestCase(unittest.TestCase):

        @unittest.skip("demonstrating skipping")
        def test_nothing(self):
            self.fail("shouldn't happen")

        @unittest.skipIf(mylib.__version__ < (1, 3),
                         "not supported in this library version")
        def test_format(self):
            # Tests that work for only a certain version of the library.
            pass

        @unittest.skipUnless(sys.platform.startswith("win"), "requires Windows")
        def test_windows_support(self):
            # windows specific testing code
            pass

        def test_maybe_skipped(self):
            if not external_resource_available():
                self.skipTest("external resource not available")
            # test code that depends on the external resource
            pass

在啰嗦模式下运行以上测试例子时，程序输出如下：

    test_format (__main__.MyTestCase) ... skipped 'not supported in this library version'
    test_nothing (__main__.MyTestCase) ... skipped 'demonstrating skipping'
    test_maybe_skipped (__main__.MyTestCase) ... skipped 'external resource not available'
    test_windows_support (__main__.MyTestCase) ... skipped 'requires Windows'

    ----------------------------------------------------------------------
    Ran 4 tests in 0.005s

    OK (skipped=4)

跳过测试类的写法跟跳过测试方法的写法相似:

    @unittest.skip("showing class skipping")
    class MySkippedTestCase(unittest.TestCase):
        def test_not_run(self):
            pass

`TestCase.setUp()` 也可以跳过测试。可以用于所需资源不可用的情况下跳过接下来的测试。

使用 `expectedFailure()` 装饰器表明这个测试预计失败。:

    class ExpectedFailureTestCase(unittest.TestCase):
        @unittest.expectedFailure
        def test_fail(self):
            self.assertEqual(1, 0, "broken")

你可以很容易地编写在测试时调用 `skip()` 的装饰器作为自定义的跳过测试装饰器。 下面这个装饰器会跳过测试，除非所传入的对象具有特定的属性:

    def skipUnlessHasattr(obj, attr):
        if hasattr(obj, attr):
            return lambda func: func
        return unittest.skip("{!r} doesn't have {!r}".format(obj, attr))

以下的装饰器和异常实现了跳过测试和预期失败两种功能：

`@``unittest.``skip`(reason)

  跳过被此装饰器装饰的测试。 reason 为测试被跳过的原因。

`@``unittest.``skipIf`(condition, reason)

  当 condition 为真时，跳过被装饰的测试。

`@``unittest.``skipUnless`(condition, reason)

  跳过被装饰的测试，除非 condition 为真。

`@``unittest.``expectedFailure`

  将测试标记为预期的失败或错误。 如果测试失败或在测试函数自身（而非在某个 test fixture 方法）中出现错误则将认为是测试成功。 如果测试通过，则将认为是测试失败。

exception `unittest.``SkipTest`(reason)

  引发此异常以跳过一个测试。

  通常来说，你可以使用 `TestCase.skipTest()` 或其中一个跳过测试的装饰器实现跳过测试的功能，而不是直接引发此异常。

被跳过的测试的 `setUp()` 和 `tearDown()` 不会被运行。被跳过的类的 `setUpClass()` 和 `tearDownClass()` 不会被运行。被跳过的模组的 `setUpModule()` 和 `tearDownModule()` 不会被运行。

## 使用子测试区分测试迭代

3.4 版新加入.

当你的几个测试之间的差异非常小，例如只有某些形参不同时，unittest 允许你使用 `subTest()` 上下文管理器在一个测试方法体的内部区分它们。

例如，以下测试:

    class NumbersTest(unittest.TestCase):

        def test_even(self):
            """
            Test that numbers between 0 and 5 are all even.
            """
            for i in range(0, 6):
                with self.subTest(i=i):
                    self.assertEqual(i % 2, 0)

可以得到以下输出:

    ======================================================================
    FAIL: test_even (__main__.NumbersTest) (i=1)
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "subtests.py", line 32, in test_even
        self.assertEqual(i % 2, 0)
    AssertionError: 1 != 0

    ======================================================================
    FAIL: test_even (__main__.NumbersTest) (i=3)
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "subtests.py", line 32, in test_even
        self.assertEqual(i % 2, 0)
    AssertionError: 1 != 0

    ======================================================================
    FAIL: test_even (__main__.NumbersTest) (i=5)
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "subtests.py", line 32, in test_even
        self.assertEqual(i % 2, 0)
    AssertionError: 1 != 0

如果不使用子测试，程序遇到第一次错误之后就会停止。而且因为``i``的值不显示，错误也更难找。

    ======================================================================
    FAIL: test_even (__main__.NumbersTest)
    ----------------------------------------------------------------------
    Traceback (most recent call last):
      File "subtests.py", line 32, in test_even
        self.assertEqual(i % 2, 0)
    AssertionError: 1 != 0

## 类与函数

本节深入介绍了 `unittest` 的 API。

### 测试用例

class `unittest.``TestCase`(methodName='runTest')

  `TestCase` 类的实例代表了 `unittest` 宇宙中的逻辑测试单元。 该类旨在被当作基类使用，特定的测试将由其实体子类来实现。 该类实现了测试运行器所需的接口以允许它驱动测试，并实现了可被测试代码用来检测和报告各种类型的失败的方法。

  每个 `TestCase` 实例将运行一个单位的基础方法：即名为 methodName 的方法。 在使用 `TestCase` 的大多数场景中，你都不需要修改 methodName 或重新实现默认的 `runTest()` 方法。

  3.2 版更變: `TestCase` 不需要提供 methodName 即可成功初始化。 这使得从交互式解释器试验 `TestCase` 更为容易。

  `TestCase` 的实例提供了三组方法：一组用来运行测试，另一组被测试实现用来检查条件和报告失败，还有一些查询方法用来收集有关测试本身的信息。

  第一组（用于运行测试的）方法是：

  `setUp`()

    为测试预备而调用的方法。 此方法会在调用测试方法之前被调用；除了 `AssertionError` 或 `SkipTest`，此方法所引发的任何异常都将被视为错误而非测试失败。 默认的实现将不做任何事情。

  `tearDown`()

    在测试方法被调用并记录结果之后立即被调用的方法。 此方法即使在测试方法引发异常时仍会被调用，因此子类中的实现将需要特别注意检查内部状态。 除 `AssertionError` 或 `SkipTest` 外，此方法所引发的任何异常都将被视为额外的错误而非测试失败（因而会增加总计错误报告数）。 此方法将只在 `setUp()` 成功执行时被调用，无论测试方法的结果如何。 默认的实现将不做任何事情。

  `setUpClass`()

    在一个单独类中的测试运行之前被调用的类方法。 `setUpClass` 会被作为唯一的参数在类上调用且必须使用 `classmethod()` 装饰器:

        @classmethod
        def setUpClass(cls):
            ...

    查看 Class and Module Fixtures 获取更详细的说明。

    3.2 版新加入.

  `tearDownClass`()

    在一个单独类的测试完成运行之后被调用的类方法。 `tearDownClass` 会被作为唯一的参数在类上调用且必须使用 `classmethod()` 装饰器:

        @classmethod
        def tearDownClass(cls):
            ...

    查看 Class and Module Fixtures 获取更详细的说明。

    3.2 版新加入.

  `run`(result=None)

    运行测试，将结果收集至作为 result 传入的 `TestResult`。 如果 result 被省略或为 `None`，则会创建一个临时的结果对象（通过调用 `defaultTestResult()` 方法）并使用它。 结果对象会被返回给 `run()` 的调用方。

    同样的效果也可通过简单地调用 `TestCase` 实例来达成。

    3.3 版更變: 之前版本的 `run` 不会返回结果。 也不会调用实例。

  `skipTest`(reason)

    在测试方法或 `setUp()` 执行期间调用此方法将跳过当前测试。 详情参见 跳过测试与预计的失败。

    3.1 版新加入.

  `subTest`(msg=None, **params)

    返回一个上下文管理器以将其中的代码块作为子测试来执行。 可选的 msg 和 params 是将在子测试失败时显示的任意值，以便让你能清楚地标识它们。

    一个测试用例可以包含任意数量的子测试声明，并且它们可以任意地嵌套。

    查看 使用子测试区分测试迭代 获取更详细的信息。

    3.4 版新加入.

  `debug`()

    运行测试而不收集结果。 这允许测试所引发的异常被传递给调用方，并可被用于支持在调试器中运行测试。

  `TestCase` 类提供了一些断言方法用于检查并报告失败。 下表列出了最常用的方法（请查看下文的其他表来了解更多的断言方法）:

  方法 | 检查对象 | 引入版本
  --- | --- | ---
  `assertEqual(a, b)` | `a == b` |
  `assertNotEqual(a, b)` | `a != b` |
  `assertTrue(x)` | `bool(x) is True` |
  `assertFalse(x)` | `bool(x) is False` |
  `assertIs(a, b)` | `a is b` | 3.1
  `assertIsNot(a, b)` | `a is not b` | 3.1
  `assertIsNone(x)` | `x is None` | 3.1
  `assertIsNotNone(x)` | `x is not None` | 3.1
  `assertIn(a, b)` | `a in b` | 3.1
  `assertNotIn(a, b)` | `a not in b` | 3.1
  `assertIsInstance(a, b)` | `isinstance(a, b)` | 3.2
  `assertNotIsInstance(a, b)` | `not isinstance(a, b)` | 3.2

  这些断言方法都支持 msg 参数，如果指定了该参数，它将被用作测试失败时的错误消息 (另请参阅 `longMessage`)。 请注意将 msg 关键字参数传给 `assertRaises()`, `assertRaisesRegex()`, `assertWarns()`, `assertWarnsRegex()` 的前提是它们必须被用作上下文管理器。

  `assertEqual`(first, second, msg=None)

    测试 first 和 second 是否相等。 如果两个值的比较结果是不相等，则测试将失败。

    此外，如果 first 和 second 的类型完全相同且属于 list, tuple, dict, set, frozenset 或 str 或者属于通过 `addTypeEqualityFunc()` 注册子类的类型则将会调用类型专属的相等判断函数以便生成更有用的默认错误消息 (另请参阅 类型专属方法列表)。

    3.1 版更變: 增加了对类型专属的相等判断函数的自动调用。

    3.2 版更變: 增加了 `assertMultiLineEqual()` 作为用于比较字符串的默认类型相等判断函数。

  `assertNotEqual`(first, second, msg=None)

    测试 first 和 second 是否不等。 如果两个值的比较结果是相等，则测试将失败。

  `assertTrue`(expr, msg=None)
  `assertFalse`(expr, msg=None)

    测试 expr 是否为真值（或假值）。

    请注意这等价于 `bool(expr) is True` 而不等价于 `expr is True` (后者要使用 `assertIs(expr, True)`)。 当存在更专门的方法时也应避免使用此方法 (例如应使用 `assertEqual(a, b)` 而不是 `assertTrue(a == b)`)，因为它们在测试失败时会提供更有用的错误消息。

  `assertIs`(first, second, msg=None)
  `assertIsNot`(first, second, msg=None)

    测试 first 和 second 是（或不是）同一个对象。

    3.1 版新加入.

  `assertIsNone`(expr, msg=None)
  `assertIsNotNone`(expr, msg=None)

    测试 expr 是 (或不是) `None`。

    3.1 版新加入.

  `assertIn`(member, container, msg=None)
  `assertNotIn`(member, container, msg=None)

    测试 member 是 (或不是) container 的成员。

    3.1 版新加入.

  `assertIsInstance`(obj, cls, msg=None)
  `assertNotIsInstance`(obj, cls, msg=None)

    测试 obj 是 (或不是) cls (此参数可以为一个类或包含类的元组，即 `isinstance()` 所接受的参数) 的实例。 要检测是否为指定类型，请使用 `assertIs(type(obj), cls)`。

    3.2 版新加入.

  还可以使用下列方法来检查异常、警告和日志消息的产生:

  方法 | 检查对象 | 引入版本
  --- | --- | ---
  `assertRaises(exc, fun, *args, **kwds)` | `fun(*args, **kwds)` 引发 exc |
  `assertRaisesRegex(exc, r, fun, *args, **kwds)` | `fun(*args, **kwds)` 引发了 exc 并且消息可与正则表达式 r 相匹配 | 3.1
  `assertWarns(warn, fun, *args, **kwds)` | `fun(*args, **kwds)` 引发了 warn | 3.2
  `assertWarnsRegex(warn, r, fun, *args, **kwds)` | `fun(*args, **kwds)` 引发了 warn 并且消息可与正则表达式 r 相匹配 | 3.2
  `assertLogs(logger, level)` | `with` 代码块在 logger 上使用最小的 level 级别写入了日志 | 3.4

  `assertRaises`(exception, callable, *args, **kwds)
  `assertRaises`(exception, *, msg=None)

    测试当 callable 附带任何同时被传给 `assertRaises()` 的位置或关键字参数被调用时是否引发了异常。 如果引发了 exception 则测试通过，如果引发了另一个异常则报错，或者如果未引发任何异常则测试失败。 要捕获一组异常中的任何一个，可以将包含多个异常类的元组作为 exception 传入。

    如果只给出了 exception 和可能的 msg 参数，则返回一个上下文管理器以便被测试的代码可以被写成内联形式而不是被写成函数:

        with self.assertRaises(SomeException):
            do_something()

    当被作为上下文管理器使用时，`assertRaises()` 接受额外的关键字参数 msg。

    上下文管理器将把捕获的异常对象存入在其 `exception` 属性中。 这适用于需要对所引发异常执行额外检查的场合:

        with self.assertRaises(SomeException) as cm:
            do_something()

        the_exception = cm.exception
        self.assertEqual(the_exception.error_code, 3)

    3.1 版更變: 添加了将 `assertRaises()` 用作上下文管理器的功能。

    3.2 版更變: 增加了 `exception` 属性。

    3.3 版更變: 增加了 msg 关键字参数在作为上下文管理器时使用。

  `assertRaisesRegex`(exception, regex, callable, *args, **kwds)
  `assertRaisesRegex`(exception, regex, *, msg=None)

    与 `assertRaises()` 类似但还会测试 regex 是否匹配被引发异常的字符串表示形式。 regex 可以是一个正则表达式对象或包含正则表达式的字符串以提供给 `re.search()` 使用。 例如:

        self.assertRaisesRegex(ValueError, "invalid literal for.*XYZ'$",
                               int, 'XYZ')

    或是：

        with self.assertRaisesRegex(ValueError, 'literal'):
           int('XYZ')

    3.1 版新加入: 以方法名``assertRaisesRegexp``添加。

    3.2 版更變: 重命名为 `assertRaisesRegex()`。

    3.3 版更變: 增加了 msg 关键字参数在作为上下文管理器时使用。

  `assertWarns`(warning, callable, *args, **kwds)
  `assertWarns`(warning, *, msg=None)

    测试当 callable 附带任何同时被传给 `assertWarns()` 的位置或关键字参数被调用时是否触发了警告。 如果触发了 warning 则测试通过，否则测试失败。 引发任何异常则报错。 要捕获一组警告中的任何一个，可将包含多个警告类的元组作为 warnings 传入。

    如果只给出了 warning 和可能的 msg 参数，则返回一个上下文管理器以便被测试的代码可以被写成内联形式而不是被写成函数:

        with self.assertWarns(SomeWarning):
            do_something()

    当被作为上下文管理器使用时，`assertWarns()` 接受额外的关键字参数 msg。

    上下文管理器将把捕获的警告对象保存在其 `warning` 属性中，并把触发警告的源代码行保存在 `filename` 和 `lineno` 属性中。 这适用于需要对捕获的警告执行额外检查的场合:

        with self.assertWarns(SomeWarning) as cm:
            do_something()

        self.assertIn('myfile.py', cm.filename)
        self.assertEqual(320, cm.lineno)

    无论被调用时警告过滤器是否就位此方法均可工作。

    3.2 版新加入.

    3.3 版更變: 增加了 msg 关键字参数在作为上下文管理器时使用。

  `assertWarnsRegex`(warning, regex, callable, *args, **kwds)
  `assertWarnsRegex`(warning, regex, *, msg=None)

    与 `assertWarns()` 类似但还会测试 regex 是否匹配被触发警告的消息文本。 regex 可以是一个正则表达式对象或包含正则表达式的字符串以提供给 `re.search()` 使用。 例如:

        self.assertWarnsRegex(DeprecationWarning,
                              r'legacy_function\(\) is deprecated',
                              legacy_function, 'XYZ')

    或是：

        with self.assertWarnsRegex(RuntimeWarning, 'unsafe frobnicating'):
            frobnicate('/etc/passwd')

    3.2 版新加入.

    3.3 版更變: 增加了 msg 关键字参数在作为上下文管理器时使用。

  `assertLogs`(logger=None, level=None)

    一个上下文管理器，它测试在 logger 或其子对象上是否至少记录了一条至少为指定 level 以上级别的消息。

    如果给出了 logger 则它应为一个 `logging.Logger` 对象或为一个指定日志记录器名称的 `str`。 默认为根日志记录器，它将捕获未被非传播型后继日志记录器所拦阻的所有消息。

    如果给出了 level 则它应为一个用数字表示的日志记录级别或其字符串形式 (例如 `"ERROR"` 或 `logging.ERROR`)。 默认为 `logging.INFO`。

    如果在 `with` 代码块内部发出了至少一条与 logger 和 level 条件相匹配的消息则测试通过，否则测试失败。

    上下文管理器返回的对象是一个记录辅助器，它会记录所匹配的日志消息。 它有两个属性:

    `records`

      所匹配的日志消息 `logging.LogRecord` 对象组成的列表。

    `output`

      由 `str` 对象组成的列表，内容为所匹配消息经格式化后的输出。

    示例:

        with self.assertLogs('foo', level='INFO') as cm:
           logging.getLogger('foo').info('first message')
           logging.getLogger('foo.bar').error('second message')
        self.assertEqual(cm.output, ['INFO:foo:first message',
                                     'ERROR:foo.bar:second message'])

    3.4 版新加入.

  还有其他一些方法可用于执行更专门的检查，例如:

  方法 | 检查对象 | 引入版本
  --- | --- | ---
  `assertAlmostEqual(a, b)` | `round(a-b, 7) == 0` |
  `assertNotAlmostEqual(a, b)` | `round(a-b, 7) != 0` |
  `assertGreater(a, b)` | `a > b` | 3.1
  `assertGreaterEqual(a, b)` | `a >= b` | 3.1
  `assertLess(a, b)` | `a < b` | 3.1
  `assertLessEqual(a, b)` | `a <= b` | 3.1
  `assertRegex(s, r)` | `r.search(s)` | 3.1
  `assertNotRegex(s, r)` | `not r.search(s)` | 3.2
  `assertCountEqual(a, b)` | a 和 b 具有同样数量的相同元素，无论其顺序如何。 | 3.2

  `assertAlmostEqual`(first, second, places=7, msg=None, delta=None)
  `assertNotAlmostEqual`(first, second, places=7, msg=None, delta=None)

    测试 first 是否约等于 second，比较的标准是计算差值并舍入到 places 所指定的十进制位数 (默认为 7 位)，再与零相比较。 请注意此方法是将结果值舍入到指定的 十进制位数 (即相当于 `round()` 函数) 而非 有效位数。

    如果提供了 delta 而非 places 则 first 和 second 之间的差值必须小于等于 (或大于) delta。

    同时提供 delta 和 places 将引发 `TypeError`。

    3.2 版更變: `assertAlmostEqual()` 会自动将几乎相等的对象视为相等。 而如果对象相等则 `assertNotAlmostEqual()` 会自动测试失败。 增加了 delta 关键字参数。

  `assertGreater`(first, second, msg=None)
  `assertGreaterEqual`(first, second, msg=None)
  `assertLess`(first, second, msg=None)
  `assertLessEqual`(first, second, msg=None)

    根据方法名分别测试 first 是否 >, >=, < 或 <= second。 如果不是，则测试失败:

        >>> self.assertGreaterEqual(3, 4)
        AssertionError: "3" unexpectedly not greater than or equal to "4"

    3.1 版新加入.

  `assertRegex`(text, regex, msg=None)
  `assertNotRegex`(text, regex, msg=None)

    测试一个 regex 是否匹配 文本。如果不匹配，错误信息中将包含匹配模式和 文本*（或部分匹配失败的 *文本）。regex 可以是正则表达式对象或能够用于 `re.search()` 的包含正则表达式的字符串。

    3.1 版新加入: 以方法名``assertRegexpMatches``添加。

    3.2 版更變: 方法 `assertRegexpMatches()` 已被改名为 `assertRegex()`。

    3.2 版新加入: `assertNotRegex()`

    3.5 版新加入: `assertNotRegexpMatches` 这个名字是 `assertNotRegex()` 的已被弃用的别名。

  `assertCountEqual`(first, second, msg=None)

    测试序列 first 与 second 是否包含同样的元素，无论其顺序如何。 当存在差异时，将生成一条错误消息来列出两个序列之间的差异。

    重复的元素 不会 在 first 和 second 的比较中被忽略。 它会检查每个元素在两个序列中的出现次数是否相同。 等价于: `assertEqual(Counter(list(first)), Counter(list(second)))` 但还适用于包含不可哈希对象的序列。

    3.2 版新加入.

  `assertEqual()` 方法会将相同类型对象的相等性检查分派给不同的类型专属方法。 这些方法已被大多数内置类型所实现，但也可以使用 `addTypeEqualityFunc()` 来注册新的方法:

  `addTypeEqualityFunc`(typeobj, function)

    注册一个由 `assertEqual()` 调用的特定类型专属方法来检查恰好为相同 typeobj (而非子类) 的两个对象是否相等。 function 必须接受两个位置参数和第三个 msg=None 关键字参数，就像 `assertEqual()` 那样。 当检测到前两个形参之间不相等时它必须引发 `self.failureException(msg)` -- 可能还会提供有用的信息并在错误消息中详细解释不相等的原因。

    3.1 版新加入.

  以下是 `assertEqual()` 自动选用的不同类型的比较方法。一般情况下不需要直接在测试中调用这些方法。

  方法 | 用作比较 | 引入版本
  --- | --- | ---
  `assertMultiLineEqual(a, b)` | 字符串 | 3.1
  `assertSequenceEqual(a, b)` | 序列 | 3.1
  `assertListEqual(a, b)` | 列表 | 3.1
  `assertTupleEqual(a, b)` | 元组 | 3.1
  `assertSetEqual(a, b)` | 集合 | 3.1
  `assertDictEqual(a, b)` | 字典 | 3.1

  `assertMultiLineEqual`(first, second, msg=None)

    测试多行字符串 first 是否与字符串 second 相等。 当不相等时将在错误消息中包括两个字符串之间差异的高亮显示。 此方法会在通过 `assertEqual()` 进行字符串比较时默认被使用。

    3.1 版新加入.

  `assertSequenceEqual`(first, second, msg=None, seq_type=None)

    测试两个序列是否相等。 如果提供了 seq_type，则 first 和 second 都必须为 seq_type 的实例否则将引发失败。 如果两个序列不相等则会构造一个错误消息来显示两者之间的差异。

    此方法不会被 `assertEqual()` 直接调用，但它会被用于实现 `assertListEqual()` 和 `assertTupleEqual()`。

    3.1 版新加入.

  `assertListEqual`(first, second, msg=None)
  `assertTupleEqual`(first, second, msg=None)

    测试两个列表或元组是否相等。 如果不相等，则会构造一个错误消息来显示两者之间的差异。 如果某个形参的类型不正确也会引发错误。 这些方法会在通过 `assertEqual()` 进行列表或元组比较时默认被使用。

    3.1 版新加入.

  `assertSetEqual`(first, second, msg=None)

    测试两个集合是否相等。 如果不相等，则会构造一个错误消息来列出两者之间的差异。 此方法会在通过 `assertEqual()` 进行集合或冻结集合比较时默认被使用。

    如果 first 或 second 没有 `set.difference()` 方法则测试失败。

    3.1 版新加入.

  `assertDictEqual`(first, second, msg=None)

    测试两个字典是否相等。 如果不相等，则会构造一个错误消息来显示两个字典的差异。 此方法会在对 `assertEqual()` 的调用中默认被用来进行字典的比较。

    3.1 版新加入.

  最后 `TestCase` 还提供了以下的方法和属性:

  `fail`(msg=None)

    无条件地发出测试失败消息，附带错误消息 msg 或 `None`。

  `failureException`

    这个类属性给出测试方法所引发的异常。 如果某个测试框架需要使用专门的异常，并可能附带额外的信息，则必须子类化该类以便与框架“正常互动”。 这个属性的初始值为 `AssertionError`。

  `longMessage`

    这个类属性决定当将一个自定义失败消息作为 msg 参数传给一个失败的 assertXYY 调用时会发生什么。默认值为 `True`。 在此情况下，自定义消息会被添加到标准失败消息的末尾。 当设为 `False` 时，自定义消息会替换标准消息。

    类设置可以通过在调用断言方法之前将一个实例属性 self.longMessage 赋值为 `True` 或 `False` 在单个测试方法中进行重载。

    类设置会在每个测试调用之前被重置。

    3.1 版新加入.

  `maxDiff`

    这个属性控制来自在测试失败时报告 diffs 的断言方法的 diffs 输出的最大长度。 它默认为 80*8 个字符。 这个属性所影响的断言方法有 `assertSequenceEqual()` (包括所有委托给它的序列比较方法), `assertDictEqual()` 以及 `assertMultiLineEqual()`。

    将 `maxDiff` 设为 `None` 表示不限制 diffs 的最大长度。

    3.2 版新加入.

  测试框架可使用下列方法在测试时收集信息:

  `countTestCases`()

    返回此测试对象所提供的测试数量。 对于 `TestCase` 实例，该数量将总是为 `1`。

  `defaultTestResult`()

    返回此测试类所要使用的测试结果类的实例（如果未向 `run()` 方法提供其他结果实例）。

    对于 `TestCase` 实例，该返回值将总是为 `TestResult` 的实例；`TestCase` 的子类应当在有必要时重载此方法。

  `id`()

    返回一个标识指定测试用例的字符串。 该返回值通常为测试方法的完整名称，包括模块名和类名。

  `shortDescription`()

    返回测试的描述，如果未提供描述则返回 `None`。 此方法的默认实现将在可用的情况下返回测试方法的文档字符串的第一行，或者返回 `None`。

    3.1 版更變: 在 3.1 中已修改此方法将测试名称添加到简短描述中，即使存在文档字符串。 这导致了与单元测试扩展的兼容性问题因而在 Python 3.2 中将添加测试名称操作改到 `TextTestResult` 中。

  `addCleanup`(function, /, *args, **kwargs)

    在 `tearDown()` 之后添加了一个要调用的函数来清理测试期间所使用的资源。 函数将按它们被添加的相反顺序被调用 (LIFO)。 它们在调用时将附带它们被添加时传给 `addCleanup()` 的任何参数和关键字参数。

    如果 `setUp()` 失败，即意味着 `tearDown()` 未被调用，则已添加的任何清理函数仍将被调用。

    3.1 版新加入.

  `doCleanups`()

    此方法会在 `tearDown()` 之后无条件地被调用，或者如果 `setUp()` 引发了异常则会在 `setUp()` 之后被调用。

    它将负责调用由 `addCleanup()` 添加的所有清理函数。 如果你需要在 `tearDown()` 之前 调用清理函数则可以自行调用 `doCleanups()`。

    `doCleanups()` 每次会弹出清理函数栈中的一个方法，因此它可以在任何时候被调用。

    3.1 版新加入.

  classmethod `addClassCleanup`(function, /, *args, **kwargs)

    在Add a function to be called after `tearDownClass()` 之后添加了一个要调用的函数来清理测试类运行期间所使用的资源。 函数将按它们被添加的相反顺序被调用 (LIFO)。 它们在调用时将附带它们被添加时传给 `addClassCleanup()` 的任何参数和关键字参数。

    如果 `setUpClass()` 失败，即意味着 `tearDownClass()` 未被调用，则已添加的任何清理函数仍将被调用。

    3.8 版新加入.

  classmethod `doClassCleanups`()

    此方法会在 `tearDownClass()` 之后无条件地被调用，或者如果 `setUpClass()` 引发了异常则会在 `setUpClass()` 之后被调用。

    It is responsible for calling all the cleanup functions added by `addClassCleanup()`. If you need cleanup functions to be called prior to `tearDownClass()` then you can call `doClassCleanups()` yourself.

    `doClassCleanups()` pops methods off the stack of cleanup functions one at a time, so it can be called at any time.

    3.8 版新加入.

class `unittest.``IsolatedAsyncioTestCase`(methodName='runTest')

  This class provides an API similar to `TestCase` and also accepts coroutines as test functions.

  3.8 版新加入.

  coroutine `asyncSetUp`()

    Method called to prepare the test fixture. This is called after `setUp()`. This is called immediately before calling the test method; other than `AssertionError` or `SkipTest`, any exception raised by this method will be considered an error rather than a test failure. The default implementation does nothing.

  coroutine `asyncTearDown`()

    Method called immediately after the test method has been called and the result recorded. This is called before `tearDown()`. This is called even if the test method raised an exception, so the implementation in subclasses may need to be particularly careful about checking internal state. Any exception, other than `AssertionError` or `SkipTest`, raised by this method will be considered an additional error rather than a test failure (thus increasing the total number of reported errors). This method will only be called if the `asyncSetUp()` succeeds, regardless of the outcome of the test method. The default implementation does nothing.

  `addAsyncCleanup`(function, /, *args, **kwargs)

    This method accepts a coroutine that can be used as a cleanup function.

  `run`(result=None)

    Sets up a new event loop to run the test, collecting the result into the `TestResult` object passed as result. If result is omitted or `None`, a temporary result object is created (by calling the `defaultTestResult()` method) and used. The result object is returned to `run()`'s caller. At the end of the test all the tasks in the event loop are cancelled.

  An example illustrating the order:

      from unittest import IsolatedAsyncioTestCase

      events = []

      class Test(IsolatedAsyncioTestCase):

          def setUp(self):
              events.append("setUp")

          async def asyncSetUp(self):
              self._async_connection = await AsyncConnection()
              events.append("asyncSetUp")

          async def test_response(self):
              events.append("test_response")
              response = await self._async_connection.get("https://example.com")
              self.assertEqual(response.status_code, 200)
              self.addAsyncCleanup(self.on_cleanup)

          def tearDown(self):
              events.append("tearDown")

          async def asyncTearDown(self):
              await self._async_connection.close()
              events.append("asyncTearDown")

          async def on_cleanup(self):
              events.append("cleanup")

      if __name__ == "__main__":
          unittest.main()

  After running the test, `events` would contain `["setUp", "asyncSetUp", "test_response", "asyncTearDown", "tearDown", "cleanup"]`.

class `unittest.``FunctionTestCase`(testFunc, setUp=None, tearDown=None, description=None)

  This class implements the portion of the `TestCase` interface which allows the test runner to drive the test, but does not provide the methods which test code can use to check and report errors. This is used to create test cases using legacy test code, allowing it to be integrated into a `unittest`-based test framework.

#### Deprecated aliases

For historical reasons, some of the `TestCase` methods had one or more aliases that are now deprecated. The following table lists the correct names along with their deprecated aliases:

> 方法名 | Deprecated alias | Deprecated alias
> --- | --- | ---
> `assertEqual()` | failUnlessEqual | assertEquals
> `assertNotEqual()` | failIfEqual | assertNotEquals
> `assertTrue()` | failUnless | assert_
> `assertFalse()` | failIf |
> `assertRaises()` | failUnlessRaises |
> `assertAlmostEqual()` | failUnlessAlmostEqual | assertAlmostEquals
> `assertNotAlmostEqual()` | failIfAlmostEqual | assertNotAlmostEquals
> `assertRegex()` |  | assertRegexpMatches
> `assertNotRegex()` |  | assertNotRegexpMatches
> `assertRaisesRegex()` |  | assertRaisesRegexp

> 3.1 版後已棄用: The fail* aliases listed in the second column have been deprecated.

> 3.2 版後已棄用: The assert* aliases listed in the third column have been deprecated.

> 3.2 版後已棄用: `assertRegexpMatches` and `assertRaisesRegexp` have been renamed to `assertRegex()` and `assertRaisesRegex()`.

> 3.5 版後已棄用: The `assertNotRegexpMatches` name is deprecated in favor of `assertNotRegex()`.

### Grouping tests

class `unittest.``TestSuite`(tests=())

  This class represents an aggregation of individual test cases and test suites. The class presents the interface needed by the test runner to allow it to be run as any other test case. Running a `TestSuite` instance is the same as iterating over the suite, running each test individually.

  If tests is given, it must be an iterable of individual test cases or other test suites that will be used to build the suite initially. Additional methods are provided to add test cases and suites to the collection later on.

  `TestSuite` objects behave much like `TestCase` objects, except they do not actually implement a test. Instead, they are used to aggregate tests into groups of tests that should be run together. Some additional methods are available to add tests to `TestSuite` instances:

  `addTest`(test)

    Add a `TestCase` or `TestSuite` to the suite.

  `addTests`(tests)

    Add all the tests from an iterable of `TestCase` and `TestSuite` instances to this test suite.

    This is equivalent to iterating over tests, calling `addTest()` for each element.

  `TestSuite` shares the following methods with `TestCase`:

  `run`(result)

    Run the tests associated with this suite, collecting the result into the test result object passed as result. Note that unlike `TestCase.run()`, `TestSuite.run()` requires the result object to be passed in.

  `debug`()

    Run the tests associated with this suite without collecting the result. This allows exceptions raised by the test to be propagated to the caller and can be used to support running tests under a debugger.

  `countTestCases`()

    Return the number of tests represented by this test object, including all individual tests and sub-suites.

  `__iter__`()

    Tests grouped by a `TestSuite` are always accessed by iteration. Subclasses can lazily provide tests by overriding `__iter__()`. Note that this method may be called several times on a single suite (for example when counting tests or comparing for equality) so the tests returned by repeated iterations before `TestSuite.run()` must be the same for each call iteration. After `TestSuite.run()`, callers should not rely on the tests returned by this method unless the caller uses a subclass that overrides `TestSuite._removeTestAtIndex()` to preserve test references.

    3.2 版更變: In earlier versions the `TestSuite` accessed tests directly rather than through iteration, so overriding `__iter__()` wasn't sufficient for providing tests.

    3.4 版更變: In earlier versions the `TestSuite` held references to each `TestCase` after `TestSuite.run()`. Subclasses can restore that behavior by overriding `TestSuite._removeTestAtIndex()`.

  In the typical usage of a `TestSuite` object, the `run()` method is invoked by a `TestRunner` rather than by the end-user test harness.

### Loading and running tests

class `unittest.``TestLoader`

  The `TestLoader` class is used to create test suites from classes and modules. Normally, there is no need to create an instance of this class; the `unittest` module provides an instance that can be shared as `unittest.defaultTestLoader`. Using a subclass or instance, however, allows customization of some configurable properties.

  `TestLoader` objects have the following attributes:

  `errors`

    A list of the non-fatal errors encountered while loading tests. Not reset by the loader at any point. Fatal errors are signalled by the relevant a method raising an exception to the caller. Non-fatal errors are also indicated by a synthetic test that will raise the original error when run.

    3.5 版新加入.

  `TestLoader` objects have the following methods:

  `loadTestsFromTestCase`(testCaseClass)

    Return a suite of all test cases contained in the `TestCase`-derived `testCaseClass`.

    A test case instance is created for each method named by `getTestCaseNames()`. By default these are the method names beginning with `test`. If `getTestCaseNames()` returns no methods, but the `runTest()` method is implemented, a single test case is created for that method instead.

  `loadTestsFromModule`(module, pattern=None)

    Return a suite of all test cases contained in the given module. This method searches module for classes derived from `TestCase` and creates an instance of the class for each test method defined for the class.

    備註

    While using a hierarchy of `TestCase`-derived classes can be convenient in sharing fixtures and helper functions, defining test methods on base classes that are not intended to be instantiated directly does not play well with this method. Doing so, however, can be useful when the fixtures are different and defined in subclasses.

    If a module provides a `load_tests` function it will be called to load the tests. This allows modules to customize test loading. This is the load_tests protocol. The pattern argument is passed as the third argument to `load_tests`.

    3.2 版更變: Support for `load_tests` added.

    3.5 版更變: The undocumented and unofficial use_load_tests default argument is deprecated and ignored, although it is still accepted for backward compatibility. The method also now accepts a keyword-only argument pattern which is passed to `load_tests` as the third argument.

  `loadTestsFromName`(name, module=None)

    Return a suite of all test cases given a string specifier.

    The specifier name is a "dotted name" that may resolve either to a module, a test case class, a test method within a test case class, a `TestSuite` instance, or a callable object which returns a `TestCase` or `TestSuite` instance. These checks are applied in the order listed here; that is, a method on a possible test case class will be picked up as "a test method within a test case class", rather than "a callable object".

    For example, if you have a module `SampleTests` containing a `TestCase`-derived class `SampleTestCase` with three test methods (`test_one()`, `test_two()`, and `test_three()`), the specifier `'SampleTests.SampleTestCase'` would cause this method to return a suite which will run all three test methods. Using the specifier `'SampleTests.SampleTestCase.test_two'` would cause it to return a test suite which will run only the `test_two()` test method. The specifier can refer to modules and packages which have not been imported; they will be imported as a side-effect.

    The method optionally resolves name relative to the given module.

    3.5 版更變: If an `ImportError` or `AttributeError` occurs while traversing name then a synthetic test that raises that error when run will be returned. These errors are included in the errors accumulated by self.errors.

  `loadTestsFromNames`(names, module=None)

    Similar to `loadTestsFromName()`, but takes a sequence of names rather than a single name. The return value is a test suite which supports all the tests defined for each name.

  `getTestCaseNames`(testCaseClass)

    Return a sorted sequence of method names found within testCaseClass; this should be a subclass of `TestCase`.

  `discover`(start_dir, pattern='test*.py', top_level_dir=None)

    Find all the test modules by recursing into subdirectories from the specified start directory, and return a TestSuite object containing them. Only test files that match pattern will be loaded. (Using shell style pattern matching.) Only module names that are importable (i.e. are valid Python identifiers) will be loaded.

    All test modules must be importable from the top level of the project. If the start directory is not the top level directory then the top level directory must be specified separately.

    If importing a module fails, for example due to a syntax error, then this will be recorded as a single error and discovery will continue. If the import failure is due to `SkipTest` being raised, it will be recorded as a skip instead of an error.

    If a package (a directory containing a file named `__init__.py`) is found, the package will be checked for a `load_tests` function. If this exists then it will be called `package.load_tests(loader, tests, pattern)`. Test discovery takes care to ensure that a package is only checked for tests once during an invocation, even if the load_tests function itself calls `loader.discover`.

    If `load_tests` exists then discovery does not recurse into the package, `load_tests` is responsible for loading all tests in the package.

    The pattern is deliberately not stored as a loader attribute so that packages can continue discovery themselves. top_level_dir is stored so `load_tests` does not need to pass this argument in to `loader.discover()`.

    start_dir can be a dotted module name as well as a directory.

    3.2 版新加入.

    3.4 版更變: Modules that raise `SkipTest` on import are recorded as skips, not errors.

    3.4 版更變: start_dir can be a namespace packages.

    3.4 版更變: Paths are sorted before being imported so that execution order is the same even if the underlying file system's ordering is not dependent on file name.

    3.5 版更變: Found packages are now checked for `load_tests` regardless of whether their path matches pattern, because it is impossible for a package name to match the default pattern.

  The following attributes of a `TestLoader` can be configured either by subclassing or assignment on an instance:

  `testMethodPrefix`

    String giving the prefix of method names which will be interpreted as test methods. The default value is `'test'`.

    This affects `getTestCaseNames()` and all the `loadTestsFrom*()` methods.

  `sortTestMethodsUsing`

    Function to be used to compare method names when sorting them in `getTestCaseNames()` and all the `loadTestsFrom*()` methods.

  `suiteClass`

    Callable object that constructs a test suite from a list of tests. No methods on the resulting object are needed. The default value is the `TestSuite` class.

    This affects all the `loadTestsFrom*()` methods.

  `testNamePatterns`

    List of Unix shell-style wildcard test name patterns that test methods have to match to be included in test suites (see `-v` option).

    If this attribute is not `None` (the default), all test methods to be included in test suites must match one of the patterns in this list. Note that matches are always performed using `fnmatch.fnmatchcase()`, so unlike patterns passed to the `-v` option, simple substring patterns will have to be converted using `*` wildcards.

    This affects all the `loadTestsFrom*()` methods.

    3.7 版新加入.

class `unittest.``TestResult`

  This class is used to compile information about which tests have succeeded and which have failed.

  A `TestResult` object stores the results of a set of tests. The `TestCase` and `TestSuite` classes ensure that results are properly recorded; test authors do not need to worry about recording the outcome of tests.

  Testing frameworks built on top of `unittest` may want access to the `TestResult` object generated by running a set of tests for reporting purposes; a `TestResult` instance is returned by the `TestRunner.run()` method for this purpose.

  `TestResult` instances have the following attributes that will be of interest when inspecting the results of running a set of tests:

  `errors`

    A list containing 2-tuples of `TestCase` instances and strings holding formatted tracebacks. Each tuple represents a test which raised an unexpected exception.

  `failures`

    A list containing 2-tuples of `TestCase` instances and strings holding formatted tracebacks. Each tuple represents a test where a failure was explicitly signalled using the `TestCase.assert*()` methods.

  `skipped`

    A list containing 2-tuples of `TestCase` instances and strings holding the reason for skipping the test.

    3.1 版新加入.

  `expectedFailures`

    A list containing 2-tuples of `TestCase` instances and strings holding formatted tracebacks. Each tuple represents an expected failure or error of the test case.

  `unexpectedSuccesses`

    A list containing `TestCase` instances that were marked as expected failures, but succeeded.

  `shouldStop`

    Set to `True` when the execution of tests should stop by `stop()`.

  `testsRun`

    The total number of tests run so far.

  `buffer`

    If set to true, `sys.stdout` and `sys.stderr` will be buffered in between `startTest()` and `stopTest()` being called. Collected output will only be echoed onto the real `sys.stdout` and `sys.stderr` if the test fails or errors. Any output is also attached to the failure / error message.

    3.2 版新加入.

  `failfast`

    If set to true `stop()` will be called on the first failure or error, halting the test run.

    3.2 版新加入.

  `tb_locals`

    If set to true then local variables will be shown in tracebacks.

    3.5 版新加入.

  `wasSuccessful`()

    Return `True` if all tests run so far have passed, otherwise returns `False`.

    3.4 版更變: Returns `False` if there were any `unexpectedSuccesses` from tests marked with the `expectedFailure()` decorator.

  `stop`()

    This method can be called to signal that the set of tests being run should be aborted by setting the `shouldStop` attribute to `True`. `TestRunner` objects should respect this flag and return without running any additional tests.

    For example, this feature is used by the `TextTestRunner` class to stop the test framework when the user signals an interrupt from the keyboard. Interactive tools which provide `TestRunner` implementations can use this in a similar manner.

  The following methods of the `TestResult` class are used to maintain the internal data structures, and may be extended in subclasses to support additional reporting requirements. This is particularly useful in building tools which support interactive reporting while tests are being run.

  `startTest`(test)

    Called when the test case test is about to be run.

  `stopTest`(test)

    Called after the test case test has been executed, regardless of the outcome.

  `startTestRun`()

    Called once before any tests are executed.

    3.1 版新加入.

  `stopTestRun`()

    Called once after all tests are executed.

    3.1 版新加入.

  `addError`(test, err)

    Called when the test case test raises an unexpected exception. err is a tuple of the form returned by `sys.exc_info()`: `(type, value, traceback)`.

    The default implementation appends a tuple `(test, formatted_err)` to the instance's `errors` attribute, where formatted_err is a formatted traceback derived from err.

  `addFailure`(test, err)

    Called when the test case test signals a failure. err is a tuple of the form returned by `sys.exc_info()`: `(type, value, traceback)`.

    The default implementation appends a tuple `(test, formatted_err)` to the instance's `failures` attribute, where formatted_err is a formatted traceback derived from err.

  `addSuccess`(test)

    Called when the test case test succeeds.

    The default implementation does nothing.

  `addSkip`(test, reason)

    Called when the test case test is skipped. reason is the reason the test gave for skipping.

    The default implementation appends a tuple `(test, reason)` to the instance's `skipped` attribute.

  `addExpectedFailure`(test, err)

    Called when the test case test fails or errors, but was marked with the `expectedFailure()` decorator.

    The default implementation appends a tuple `(test, formatted_err)` to the instance's `expectedFailures` attribute, where formatted_err is a formatted traceback derived from err.

  `addUnexpectedSuccess`(test)

    Called when the test case test was marked with the `expectedFailure()` decorator, but succeeded.

    The default implementation appends the test to the instance's `unexpectedSuccesses` attribute.

  `addSubTest`(test, subtest, outcome)

    Called when a subtest finishes. test is the test case corresponding to the test method. subtest is a custom `TestCase` instance describing the subtest.

    If outcome is `None`, the subtest succeeded. Otherwise, it failed with an exception where outcome is a tuple of the form returned by `sys.exc_info()`: `(type, value, traceback)`.

    The default implementation does nothing when the outcome is a success, and records subtest failures as normal failures.

    3.4 版新加入.

class `unittest.``TextTestResult`(stream, descriptions, verbosity)

  A concrete implementation of `TestResult` used by the `TextTestRunner`.

  3.2 版新加入: This class was previously named `_TextTestResult`. The old name still exists as an alias but is deprecated.

`unittest.``defaultTestLoader`

  Instance of the `TestLoader` class intended to be shared. If no customization of the `TestLoader` is needed, this instance can be used instead of repeatedly creating new instances.

class `unittest.``TextTestRunner`(stream=None, descriptions=True, verbosity=1, failfast=False, buffer=False, resultclass=None, warnings=None, *, tb_locals=False)

  A basic test runner implementation that outputs results to a stream. If stream is `None`, the default, `sys.stderr` is used as the output stream. This class has a few configurable parameters, but is essentially very simple. Graphical applications which run test suites should provide alternate implementations. Such implementations should accept `**kwargs` as the interface to construct runners changes when features are added to unittest.

  By default this runner shows `DeprecationWarning`, `PendingDeprecationWarning`, `ResourceWarning` and `ImportWarning` even if they are ignored by default. Deprecation warnings caused by deprecated unittest methods are also special-cased and, when the warning filters are `'default'` or `'always'`, they will appear only once per-module, in order to avoid too many warning messages. This behavior can be overridden using Python's `-Wd` or `-Wa` options (see Warning control) and leaving warnings to `None`.

  3.2 版更變: Added the `warnings` argument.

  3.2 版更變: The default stream is set to `sys.stderr` at instantiation time rather than import time.

  3.5 版更變: Added the tb_locals parameter.

  `_makeResult`()

    This method returns the instance of `TestResult` used by `run()`. It is not intended to be called directly, but can be overridden in subclasses to provide a custom `TestResult`.

    `_makeResult()` instantiates the class or callable passed in the `TextTestRunner` constructor as the `resultclass` argument. It defaults to `TextTestResult` if no `resultclass` is provided. The result class is instantiated with the following arguments:

        stream, descriptions, verbosity

  `run`(test)

    This method is the main public interface to the `TextTestRunner`. This method takes a `TestSuite` or `TestCase` instance. A `TestResult` is created by calling `_makeResult()` and the test(s) are run and the results printed to stdout.

`unittest.``main`(module='__main__', defaultTest=None, argv=None, testRunner=None, testLoader=unittest.defaultTestLoader, exit=True, verbosity=1, failfast=None, catchbreak=None, buffer=None, warnings=None)

  A command-line program that loads a set of tests from module and runs them; this is primarily for making test modules conveniently executable. The simplest use for this function is to include the following line at the end of a test script:

      if __name__ == '__main__':
          unittest.main()

  You can run tests with more detailed information by passing in the verbosity argument:

      if __name__ == '__main__':
          unittest.main(verbosity=2)

  The defaultTest argument is either the name of a single test or an iterable of test names to run if no test names are specified via argv. If not specified or `None` and no test names are provided via argv, all tests found in module are run.

  The argv argument can be a list of options passed to the program, with the first element being the program name. If not specified or `None`, the values of `sys.argv` are used.

  The testRunner argument can either be a test runner class or an already created instance of it. By default `main` calls `sys.exit()` with an exit code indicating success or failure of the tests run.

  The testLoader argument has to be a `TestLoader` instance, and defaults to `defaultTestLoader`.

  `main` supports being used from the interactive interpreter by passing in the argument `exit=False`. This displays the result on standard output without calling `sys.exit()`:

      >>> from unittest import main
      >>> main(module='test_module', exit=False)

  The failfast, catchbreak and buffer parameters have the same effect as the same-name command-line options.

  The warnings argument specifies the warning filter that should be used while running the tests. If it's not specified, it will remain `None` if a `-W` option is passed to python (see Warning control), otherwise it will be set to `'default'`.

  Calling `main` actually returns an instance of the `TestProgram` class. This stores the result of the tests run as the `result` attribute.

  3.1 版更變: The exit parameter was added.

  3.2 版更變: The verbosity, failfast, catchbreak, buffer and warnings parameters were added.

  3.4 版更變: The defaultTest parameter was changed to also accept an iterable of test names.

#### load_tests Protocol

3.2 版新加入.

Modules or packages can customize how tests are loaded from them during normal test runs or test discovery by implementing a function called `load_tests`.

If a test module defines `load_tests` it will be called by `TestLoader.loadTestsFromModule()` with the following arguments:

    load_tests(loader, standard_tests, pattern)

where pattern is passed straight through from `loadTestsFromModule`. It defaults to `None`.

It should return a `TestSuite`.

loader is the instance of `TestLoader` doing the loading. standard_tests are the tests that would be loaded by default from the module. It is common for test modules to only want to add or remove tests from the standard set of tests. The third argument is used when loading packages as part of test discovery.

A typical `load_tests` function that loads tests from a specific set of `TestCase` classes may look like:

    test_cases = (TestCase1, TestCase2, TestCase3)

    def load_tests(loader, tests, pattern):
        suite = TestSuite()
        for test_class in test_cases:
            tests = loader.loadTestsFromTestCase(test_class)
            suite.addTests(tests)
        return suite

If discovery is started in a directory containing a package, either from the command line or by calling `TestLoader.discover()`, then the package `__init__.py` will be checked for `load_tests`. If that function does not exist, discovery will recurse into the package as though it were just another directory. Otherwise, discovery of the package's tests will be left up to `load_tests` which is called with the following arguments:

    load_tests(loader, standard_tests, pattern)

This should return a `TestSuite` representing all the tests from the package. (`standard_tests` will only contain tests collected from `__init__.py`.)

Because the pattern is passed into `load_tests` the package is free to continue (and potentially modify) test discovery. A 'do nothing' `load_tests` function for a test package would look like:

    def load_tests(loader, standard_tests, pattern):
        # top level directory cached on loader instance
        this_dir = os.path.dirname(__file__)
        package_tests = loader.discover(start_dir=this_dir, pattern=pattern)
        standard_tests.addTests(package_tests)
        return standard_tests

3.5 版更變: Discovery no longer checks package names for matching pattern due to the impossibility of package names matching the default pattern.

## Class and Module Fixtures

Class and module level fixtures are implemented in `TestSuite`. When the test suite encounters a test from a new class then `tearDownClass()` from the previous class (if there is one) is called, followed by `setUpClass()` from the new class.

Similarly if a test is from a different module from the previous test then `tearDownModule` from the previous module is run, followed by `setUpModule` from the new module.

After all the tests have run the final `tearDownClass` and `tearDownModule` are run.

Note that shared fixtures do not play well with [potential] features like test parallelization and they break test isolation. They should be used with care.

The default ordering of tests created by the unittest test loaders is to group all tests from the same modules and classes together. This will lead to `setUpClass` / `setUpModule` (etc) being called exactly once per class and module. If you randomize the order, so that tests from different modules and classes are adjacent to each other, then these shared fixture functions may be called multiple times in a single test run.

Shared fixtures are not intended to work with suites with non-standard ordering. A `BaseTestSuite` still exists for frameworks that don't want to support shared fixtures.

If there are any exceptions raised during one of the shared fixture functions the test is reported as an error. Because there is no corresponding test instance an `_ErrorHolder` object (that has the same interface as a `TestCase`) is created to represent the error. If you are just using the standard unittest test runner then this detail doesn't matter, but if you are a framework author it may be relevant.

### setUpClass and tearDownClass

These must be implemented as class methods:

    import unittest

    class Test(unittest.TestCase):
        @classmethod
        def setUpClass(cls):
            cls._connection = createExpensiveConnectionObject()

        @classmethod
        def tearDownClass(cls):
            cls._connection.destroy()

If you want the `setUpClass` and `tearDownClass` on base classes called then you must call up to them yourself. The implementations in `TestCase` are empty.

If an exception is raised during a `setUpClass` then the tests in the class are not run and the `tearDownClass` is not run. Skipped classes will not have `setUpClass` or `tearDownClass` run. If the exception is a `SkipTest` exception then the class will be reported as having been skipped instead of as an error.

### setUpModule and tearDownModule

These should be implemented as functions:

    def setUpModule():
        createConnection()

    def tearDownModule():
        closeConnection()

If an exception is raised in a `setUpModule` then none of the tests in the module will be run and the `tearDownModule` will not be run. If the exception is a `SkipTest` exception then the module will be reported as having been skipped instead of as an error.

To add cleanup code that must be run even in the case of an exception, use `addModuleCleanup`:

`unittest.``addModuleCleanup`(function, /, *args, **kwargs)

  Add a function to be called after `tearDownModule()` to cleanup resources used during the test class. Functions will be called in reverse order to the order they are added (LIFO). They are called with any arguments and keyword arguments passed into `addModuleCleanup()` when they are added.

  If `setUpModule()` fails, meaning that `tearDownModule()` is not called, then any cleanup functions added will still be called.

  3.8 版新加入.

`unittest.``doModuleCleanups`()

  This function is called unconditionally after `tearDownModule()`, or after `setUpModule()` if `setUpModule()` raises an exception.

  It is responsible for calling all the cleanup functions added by `addCleanupModule()`. If you need cleanup functions to be called prior to `tearDownModule()` then you can call `doModuleCleanups()` yourself.

  `doModuleCleanups()` pops methods off the stack of cleanup functions one at a time, so it can be called at any time.

  3.8 版新加入.

## 信号处理

3.2 版新加入.

The `-c/--catch` command-line option to unittest, along with the `catchbreak` parameter to `unittest.main()`, provide more friendly handling of control-C during a test run. With catch break behavior enabled control-C will allow the currently running test to complete, and the test run will then end and report all the results so far. A second control-c will raise a `KeyboardInterrupt` in the usual way.

The control-c handling signal handler attempts to remain compatible with code or tests that install their own `signal.SIGINT` handler. If the `unittest` handler is called but isn't the installed `signal.SIGINT` handler, i.e. it has been replaced by the system under test and delegated to, then it calls the default handler. This will normally be the expected behavior by code that replaces an installed handler and delegates to it. For individual tests that need `unittest` control-c handling disabled the `removeHandler()` decorator can be used.

There are a few utility functions for framework authors to enable control-c handling functionality within test frameworks.

`unittest.``installHandler`()

  Install the control-c handler. When a `signal.SIGINT` is received (usually in response to the user pressing control-c) all registered results have `stop()` called.

`unittest.``registerResult`(result)

  Register a `TestResult` object for control-c handling. Registering a result stores a weak reference to it, so it doesn't prevent the result from being garbage collected.

  Registering a `TestResult` object has no side-effects if control-c handling is not enabled, so test frameworks can unconditionally register all results they create independently of whether or not handling is enabled.

`unittest.``removeResult`(result)

  Remove a registered result. Once a result has been removed then `stop()` will no longer be called on that result object in response to a control-c.

`unittest.``removeHandler`(function=None)

  When called without arguments this function removes the control-c handler if it has been installed. This function can also be used as a test decorator to temporarily remove the handler while the test is being executed:

      @unittest.removeHandler
      def test_signal_handling(self):
          ...