`unittest` --- 單元測試框架?

（如果你已經對測試的概念比較熟悉了，你可能想直接跳轉到這一部分斷言方法。）

unittest 單元測試框架是受到 JUnit 的啟發，與其他語言中的主流單元測試框架有著相似的風格。其支持測試自動化，配置共享和關機代碼測試。支持將測試樣例聚合到測試集中，并將測試與報告框架獨立。

為了實現這些，unittest 通過面向對象的方式支持了一些重要的概念。

測試腳手架: test fixture 表示為了開展一項或多項測試所需要進行的準備工作，以及所有相關的清理操作。舉個例子，這可能包含創建臨時或代理的數據庫、目錄，再或者啟動一個服務器進程。
測試用例: 一個測試用例是一個獨立的測試單元。它檢查輸入特定的數據時的響應。 unittest 提供一個基類： TestCase ，用于新建測試用例。
測試套件: test suite 是一系列的測試用例，或測試套件，或兩者皆有。它用于歸檔需要一起執行的測試。
測試運行器（test runner）: test runner 是一個用于執行和輸出測試結果的組件。這個運行器可能使用圖形接口、文本接口，或返回一個特定的值表示運行測試的結果。

參見

doctest --- 文檔測試模塊: 另一個風格完全不同的測試模塊。
簡單 Smalltalk 測試：便用模式: Kent Beck 有關使用 unittest 所共享的模式的測試框架的原創論文。
pytest: 第三方單元測試框架，提供輕量化的語法來編寫測試，例如：assert func(10) == 42。
Python 測試工具分類: 一個 Python 測試工具的詳細列表，包含測試框架和模擬對象庫。
Python 中的測試郵件列表: 一個討論 Python 中的測試和測試工具的特別興趣小組。

包含在源代碼分發中的 Tools/unittestgui/unittestgui.py 文件是一個用于顯示測試覆蓋率和執行情況的 GUI 工具。它的目的是給那些單元測試的新手們提供方便。在生產環境中建議測試應由持續集成系統（continuous integration system）驅動，例如：Buildbot、 Jenkins 或 Hudson。

基本實例?

unittest 模塊提供了一系列創建和運行測試的工具。這一段落演示了這些工具的一小部分，但也足以滿足大部分用戶的需求。

這是一段簡短的代碼，來測試三種字符串方法:

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()

繼承 unittest.TestCase 就創建了一個測試樣例。上述三個獨立的測試是三個類的方法，這些方法的命名都以 test 開頭。這個命名約定告訴測試運行者類的哪些方法表示測試。

每個測試的關鍵是：調用 assertEqual() 來檢查預期的輸出；調用 assertTrue() 或 assertFalse() 來驗證一個條件；調用 assertRaises() 來驗證拋出了一個特定的異常。使用這些方法而不是 assert 語句是為了讓測試運行者能聚合所有的測試結果并產生結果報告。

通過 setUp() 和 tearDown() 方法，可以設置測試開始前與完成后需要執行的指令。在組織你的測試代碼中，對此有更為詳細的描述。

最后的代碼塊中，演示了運行測試的一個簡單的方法。 unittest.main() 提供了一個測試腳本的命令行接口。當在命令行運行該測試腳本，上文的腳本生成如以下格式的輸出:

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

OK

在調用測試腳本時添加 -v 參數使 unittest.main() 顯示更為詳細的信息，生成如以下形式的輸出:

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

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

OK

以上例子演示了 unittest 中最常用的、足夠滿足許多日常測試需求的特性。文檔的剩余部分詳述該框架的完整特性。

命令行界面?

unittest 模塊可以通過命令行運行模塊、類和獨立測試方法的測試:

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

你可以傳入模塊名、類或方法名或他們的任意組合。

同樣的，測試模塊可以通過文件路徑指定:

python -m unittest tests/test_something.py

這樣就可以使用 shell 的文件名補全指定測試模塊。所指定的文件仍需要可以被作為模塊導入。路徑通過去除 '.py' 、把分隔符轉換為 '.' 轉換為模塊名。若你需要執行不能被作為模塊導入的測試文件，你需要直接執行該測試文件。

在運行測試時，你可以通過添加 -v 參數獲取更詳細（更多的冗余）的信息。

python -m unittest -v test_module

當運行時不包含參數，開始探索性測試

python -m unittest

用于獲取命令行選項列表：

python -m unittest -h

在 3.2 版更改: 在早期版本中，只支持運行獨立的測試方法，而不支持模塊和類。

命令行選項?

unittest supports these command-line options:

-b, --buffer?: 在測試運行時，標準輸出流與標準錯誤流會被放入緩沖區。成功的測試的運行時輸出會被丟棄；測試不通過時，測試運行中的輸出會正常顯示，錯誤會被加入到測試失敗信息。

-c, --catch?

當測試正在運行時， Control-C 會等待當前測試完成，并在完成后報告已執行的測試的結果。當再次按下 Control-C 時，引發平常的 KeyboardInterrupt 異常。

See Signal Handling for the functions that provide this functionality.

-f, --failfast?: 當出現第一個錯誤或者失敗時，停止運行測試。

-k?

只運行匹配模式或子串的測試方法和類。可以多次使用這個選項，以便包含匹配子串的所有測試用例。

包含通配符（*）的模式使用 fnmatch.fnmatchcase() 對測試名稱進行匹配。另外，該匹配是大小寫敏感的。

模式對測試加載器導入的測試方法全名進行匹配。

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?: 在回溯中顯示局部變量。

3.2 新版功能: 添加命令行選項 -b, -c 和 -f 。

3.5 新版功能: 命令行選項 --locals 。

3.7 新版功能: 命令行選項 -k 。

命令行亦可用于探索性測試，以運行一個項目的所有測試或其子集。

探索性測試?

3.2 新版功能.

Unittest支持簡單的測試搜索。若需要使用探索性測試，所有的測試文件必須是 modules 或 packages （包括 namespace packages )并可從項目根目錄導入（即它們的文件名必須是有效的 identifiers ）。

探索性測試在 TestLoader.discover() 中實現，但也可以通過命令行使用。它在命令行中的基本用法如下：

cd project_directory
python -m unittest discover

注解

方便起見， python -m unittest 與 python -m unittest discover 等價。如果你需要向探索性測試傳入參數，必須顯式地使用 discover 子命令。

discover 有以下選項：

-v, --verbose?: 更詳細地輸出結果。

-s, --start-directory directory?: 開始進行搜索的目錄(默認值為當前目錄 . )。

-p, --pattern pattern?: 用于匹配測試文件的模式（默認為 test*.py ）。

-t, --top-level-directory directory?: 指定項目的最上層目錄（通常為開始時所在目錄）。

-s ，-p 和 -t 選項可以按順序作為位置參數傳入。以下兩條命令是等價的：

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

正如可以傳入路徑那樣，傳入一個包名作為起始目錄也是可行的，如 myproject.subpackage.test 。你提供的包名會被導入，它在文件系統中的位置會被作為起始目錄。

警告

探索性測試通過導入測試對測試進行加載。在找到所有你指定的開始目錄下的所有測試文件后，它把路徑轉換為包名并進行導入。如 foo/bar/baz.py 會被導入為 foo.bar.baz 。

如果你有一個全局安裝的包，并嘗試對這個包的副本進行探索性測試，可能會從錯誤的地方開始導入。如果出現這種情況，測試會輸出警告并退出。

如果你使用包名而不是路徑作為開始目錄，搜索時會假定它導入的是你想要的目錄，所以你不會收到警告。

測試模塊和包可以通過 load_tests protocol 自定義測試的加載和搜索。

在 3.4 版更改: 探索性測試支持命名空間包（ namespace packages ）。

組織你的測試代碼?

單元測試的構建單位是 test cases ：獨立的、包含執行條件與正確性檢查的方案。在 unittest 中，測試用例表示為 unittest.TestCase 的實例。通過編寫 TestCase 的子類或使用 FunctionTestCase 編寫你自己的測試用例。

一個 TestCase 實例的測試代碼必須是完全自含的，因此它可以獨立運行，或與其它任意組合任意數量的測試用例一起運行。

TestCase 的最簡單的子類需要實現一個測試方法（例如一個命名以 test 開頭的方法）以執行特定的測試代碼：

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，為了進行測試，我們使用了基類 TestCase 提供的其中一個 assert*() 方法。若測試不通過，將會引發一個帶有說明信息的異常，并且 unittest 會將這個測試用例標記為測試不通過。任何其它類型的異常將會被當做錯誤處理。

可能同時存在多個前置操作相同的測試，我們可以把測試的前置操作從測試代碼中拆解出來，并實現測試前置方法 setUp() 。在運行測試時，測試框架會自動地為每個單獨測試調用前置方法。

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')

注解

多個測試運行的順序由內置字符串排序方法對測試名進行排序的結果決定。

在測試運行時，若 setUp() 方法引發異常，測試框架會認為測試發生了錯誤，因此測試方法不會被運行。

相似的，我們提供了一個 tearDown() 方法在測試方法運行后進行清理工作。

import unittest

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

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

若 setUp() 成功運行，無論測試方法是否成功，都會運行 tearDown() 。

這樣的一個測試代碼運行的環境被稱為 test fixture 。一個新的 TestCase 實例作為一個測試腳手架，用于運行各個獨立的測試方法。在運行每個測試時，setUp() 、tearDown() 和 __init__() 會被調用一次。

建議你根據所測試的功能，將測試用 TestCase 實現集合起來。unittest 為此提供了機制：test suite，以 unittest 的類 TestSuite 為代表。大部分情況下，調用 unittest.main() 即可，并且它會為你集合所有模塊的測試用例并執行。

然而，如果你需要自定義你的測試套件的話，你可以參考以下方法組織你的測試：

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())

你可以把測試用例和測試套件放在與被測試代碼相同的模塊中（比如 widget.py），但將測試代碼放在單獨的模塊中（比如 test_widget.py）有幾個優勢。

測試模塊可以從命令行被獨立調用。
更容易在分發的代碼中剝離測試代碼。
降低沒有好理由的情況下修改測試代碼以通過測試的誘惑。
測試代碼應比被測試代碼更少地被修改。
被測試代碼可以更容易地被重構。
對用 C 語言寫成的模塊無論如何都得單獨寫成一個模塊，為什么不保持一致呢？
如果測試策略發生了改變，沒有必要修改源代碼。

復用已有的測試代碼?

一些用戶希望直接使用 unittest 運行已有的測試代碼，而不需要把已有的每個測試函數轉化為一個 TestCase 的子類。

因此， unittest 提供 FunctionTestCase 類。這個 TestCase 的子類可用于打包已有的測試函數，并支持設置前置與后置函數。

假定有一個測試函數：

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

可以創建等價的測試用例如下，其中前置和后置方法是可選的。

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

注解

可以用 FunctionTestCase 快速將現有的測試轉換成基于 unittest 的測試，但不推薦。花點時間繼承 TestCase 會讓以后重構測試無比輕松。

在某些情況下，現有的測試可能是用 doctest 模塊編寫的。如果是這樣， doctest 提供了一個 DocTestSuite 類，可以從現有基于 doctest 的測試中自動構建 unittest.TestSuite 用例。

跳過測試與預計的失敗?

3.1 新版功能.

Unittest 支持跳過單個或整組的測試用例。它還支持把測試標注成“預期失敗”的測試。這些壞測試會失敗，但不會算進 TestResult 的失敗里。

Skipping a test is simply a matter of using the skip() decorator or one of its conditional variants, calling TestCase.skipTest() within a setUp() or test method, or raising SkipTest directly.

跳過測試的基本用法如下:

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

在啰嗦模式下運行以上測試例子時，程序輸出如下：

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)

跳過測試類的寫法跟跳過測試方法的寫法相似:

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

TestCase.setUp() 也可以跳過測試。可以用于所需資源不可用的情況下跳過接下來的測試。

使用 expectedFailure() 裝飾器表明這個測試預計失敗。:

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

It's easy to roll your own skipping decorators by making a decorator that calls skip() on the test when it wants it to be skipped. This decorator skips the test unless the passed object has a certain attribute:

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

以下的裝飾器和異常實現了跳過測試和預期失敗兩種功能：

@unittest.skip(reason)?: 跳過被此裝飾器裝飾的測試。 reason 為測試被跳過的原因。

@unittest.skipIf(condition, reason)?: 當 condition 為真時，跳過被裝飾的測試。

@unittest.skipUnless(condition, reason)?: 跳過被裝飾的測試，除非 condition 為真。

@unittest.expectedFailure?: 把測試標記為預計失敗。如果測試不通過，會被認為測試成功；如果測試通過了，則被認為是測試失敗。

exception unittest.SkipTest(reason)?

引發此異常以跳過一個測試。

通常來說，你可以使用 TestCase.skipTest() 或其中一個跳過測試的裝飾器實現跳過測試的功能，而不是直接引發此異常。

被跳過的測試的 setUp() 和 tearDown() 不會被運行。被跳過的類的 setUpClass() 和 tearDownClass() 不會被運行。被跳過的模組的 setUpModule() 和 tearDownModule() 不會被運行。

Distinguishing test iterations using subtests?

3.4 新版功能.

When there are very small differences among your tests, for instance some parameters, unittest allows you to distinguish them inside the body of a test method using the subTest() context manager.

例如，以下測試:

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)

可以得到以下輸出:

======================================================================
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

如果不使用子測試，程序遇到第一次錯誤之后就會停止。而且因為``i``的值不顯示，錯誤也更難找。

======================================================================
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

類與函數?

本節深入介紹了 unittest 的 API。

測試用例?

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

Instances of the TestCase class represent the logical test units in the unittest universe. This class is intended to be used as a base class, with specific tests being implemented by concrete subclasses. This class implements the interface needed by the test runner to allow it to drive the tests, and methods that the test code can use to check for and report various kinds of failure.

Each instance of TestCase will run a single base method: the method named methodName. In most uses of TestCase, you will neither change the methodName nor reimplement the default runTest() method.

在 3.2 版更改: TestCase can be instantiated successfully without providing a methodName. This makes it easier to experiment with TestCase from the interactive interpreter.

TestCase instances provide three groups of methods: one group used to run the test, another used by the test implementation to check conditions and report failures, and some inquiry methods allowing information about the test itself to be gathered.

第一組（用于運行測試的）方法是：

setUp()?: Method called to prepare the test fixture. 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.

tearDown()?: Method called immediately after the test method has been called and the result recorded. 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 setUp() succeeds, regardless of the outcome of the test method. The default implementation does nothing.

setUpClass()?

A class method called before tests in an individual class are run. setUpClass is called with the class as the only argument and must be decorated as a classmethod():

@classmethod
def setUpClass(cls):
    ...

查看 Class and Module Fixtures 獲取更詳細的說明。

3.2 新版功能.

tearDownClass()?

A class method called after tests in an individual class have run. tearDownClass is called with the class as the only argument and must be decorated as a classmethod():

@classmethod
def tearDownClass(cls):
    ...

查看 Class and Module Fixtures 獲取更詳細的說明。

3.2 新版功能.

run(result=None)?

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.

The same effect may be had by simply calling the TestCase instance.

在 3.3 版更改: Previous versions of run did not return the result. Neither did calling an instance.

skipTest(reason)?: Calling this during a test method or setUp() skips the current test. See 跳過測試與預計的失敗 for more information.

3.1 新版功能.

subTest(msg=None, **params)?

Return a context manager which executes the enclosed code block as a subtest. msg and params are optional, arbitrary values which are displayed whenever a subtest fails, allowing you to identify them clearly.

A test case can contain any number of subtest declarations, and they can be arbitrarily nested.

查看 Distinguishing test iterations using subtests 獲取更詳細的信息。

3.4 新版功能.

debug()?: Run the test 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.

The TestCase class provides several assert methods to check for and report failures. The following table lists the most commonly used methods (see the tables below for more assert methods):

Method	Checks that	New in
`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

All the assert methods accept a msg argument that, if specified, is used as the error message on failure (see also longMessage). Note that the msg keyword argument can be passed to assertRaises(), assertRaisesRegex(), assertWarns(), assertWarnsRegex() only when they are used as a context manager.

assertEqual(first, second, msg=None)?

Test that first and second are equal. If the values do not compare equal, the test will fail.

In addition, if first and second are the exact same type and one of list, tuple, dict, set, frozenset or str or any type that a subclass registers with addTypeEqualityFunc() the type-specific equality function will be called in order to generate a more useful default error message (see also the list of type-specific methods).

在 3.1 版更改: Added the automatic calling of type-specific equality function.

在 3.2 版更改: assertMultiLineEqual() added as the default type equality function for comparing strings.

assertNotEqual(first, second, msg=None)?: Test that first and second are not equal. If the values do compare equal, the test will fail.

assertTrue(expr, msg=None)?

assertFalse(expr, msg=None)?

Test that expr is true (or false).

Note that this is equivalent to bool(expr) is True and not to expr is True (use assertIs(expr, True) for the latter). This method should also be avoided when more specific methods are available (e.g. assertEqual(a, b) instead of assertTrue(a == b)), because they provide a better error message in case of failure.

assertIs(first, second, msg=None)?
assertIsNot(first, second, msg=None)?: Test that first and second evaluate (or don't evaluate) to the same object.

3.1 新版功能.

assertIsNone(expr, msg=None)?
assertIsNotNone(expr, msg=None)?: Test that expr is (or is not) None.

3.1 新版功能.

assertIn(member, container, msg=None)?
assertNotIn(member, container, msg=None)?: Test that member is (or is not) in container.

3.1 新版功能.

assertIsInstance(obj, cls, msg=None)?
assertNotIsInstance(obj, cls, msg=None)?: Test that obj is (or is not) an instance of cls (which can be a class or a tuple of classes, as supported by isinstance()). To check for the exact type, use assertIs(type(obj), cls).

3.2 新版功能.

It is also possible to check the production of exceptions, warnings, and log messages using the following methods:

Method	Checks that	New in
`assertRaises(exc, fun, args, *kwds)`	`fun(args, kwds)` raises exc*
`assertRaisesRegex(exc, r, fun, args, *kwds)`	`fun(args, kwds)` raises exc* and the message matches regex r	3.1
`assertWarns(warn, fun, args, *kwds)`	`fun(args, kwds)` raises warn*	3.2
`assertWarnsRegex(warn, r, fun, args, *kwds)`	`fun(args, kwds)` raises warn* and the message matches regex r	3.2
`assertLogs(logger, level)`	The `with` block logs on logger with minimum level	3.4

assertRaises(exception, callable, *args, **kwds)?

assertRaises(exception, *, msg=None)

Test that an exception is raised when callable is called with any positional or keyword arguments that are also passed to assertRaises(). The test passes if exception is raised, is an error if another exception is raised, or fails if no exception is raised. To catch any of a group of exceptions, a tuple containing the exception classes may be passed as exception.

If only the exception and possibly the msg arguments are given, return a context manager so that the code under test can be written inline rather than as a function:

with self.assertRaises(SomeException):
    do_something()

When used as a context manager, assertRaises() accepts the additional keyword argument msg.

The context manager will store the caught exception object in its exception attribute. This can be useful if the intention is to perform additional checks on the exception raised:

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

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

在 3.1 版更改: Added the ability to use assertRaises() as a context manager.

在 3.2 版更改: Added the exception attribute.

在 3.3 版更改: Added the msg keyword argument when used as a context manager.

assertRaisesRegex(exception, regex, callable, *args, **kwds)?

assertRaisesRegex(exception, regex, *, msg=None)

Like assertRaises() but also tests that regex matches on the string representation of the raised exception. regex may be a regular expression object or a string containing a regular expression suitable for use by re.search(). Examples:

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

或者：

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

3.1 新版功能: 以方法名``assertRaisesRegexp``添加。

在 3.2 版更改: Renamed to assertRaisesRegex().

在 3.3 版更改: Added the msg keyword argument when used as a context manager.

assertWarns(warning, callable, *args, **kwds)?

assertWarns(warning, *, msg=None)

Test that a warning is triggered when callable is called with any positional or keyword arguments that are also passed to assertWarns(). The test passes if warning is triggered and fails if it isn't. Any exception is an error. To catch any of a group of warnings, a tuple containing the warning classes may be passed as warnings.

If only the warning and possibly the msg arguments are given, return a context manager so that the code under test can be written inline rather than as a function:

with self.assertWarns(SomeWarning):
    do_something()

When used as a context manager, assertWarns() accepts the additional keyword argument msg.

The context manager will store the caught warning object in its warning attribute, and the source line which triggered the warnings in the filename and lineno attributes. This can be useful if the intention is to perform additional checks on the warning caught:

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

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

This method works regardless of the warning filters in place when it is called.

3.2 新版功能.

在 3.3 版更改: Added the msg keyword argument when used as a context manager.

assertWarnsRegex(warning, regex, callable, *args, **kwds)?

assertWarnsRegex(warning, regex, *, msg=None)

Like assertWarns() but also tests that regex matches on the message of the triggered warning. regex may be a regular expression object or a string containing a regular expression suitable for use by re.search(). Example:

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

或者：

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

3.2 新版功能.

在 3.3 版更改: Added the msg keyword argument when used as a context manager.

assertLogs(logger=None, level=None)?

A context manager to test that at least one message is logged on the logger or one of its children, with at least the given level.

If given, logger should be a logging.Logger object or a str giving the name of a logger. The default is the root logger, which will catch all messages.

If given, level should be either a numeric logging level or its string equivalent (for example either "ERROR" or logging.ERROR). The default is logging.INFO.

The test passes if at least one message emitted inside the with block matches the logger and level conditions, otherwise it fails.

The object returned by the context manager is a recording helper which keeps tracks of the matching log messages. It has two attributes:

records?: A list of logging.LogRecord objects of the matching log messages.

output?: A list of str objects with the formatted output of matching messages.

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 新版功能.

There are also other methods used to perform more specific checks, such as:

Method	Checks that	New in
`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 and b have the same elements in the same number, regardless of their order.	3.2

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

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

Test that first and second are approximately (or not approximately) equal by computing the difference, rounding to the given number of decimal places (default 7), and comparing to zero. Note that these methods round the values to the given number of decimal places (i.e. like the round() function) and not significant digits.

If delta is supplied instead of places then the difference between first and second must be less or equal to (or greater than) delta.

Supplying both delta and places raises a TypeError.

在 3.2 版更改: assertAlmostEqual() automatically considers almost equal objects that compare equal. assertNotAlmostEqual() automatically fails if the objects compare equal. Added the delta keyword argument.

assertGreater(first, second, msg=None)?

assertGreaterEqual(first, second, msg=None)?

assertLess(first, second, msg=None)?

assertLessEqual(first, second, msg=None)?

Test that first is respectively >, >=, < or <= than second depending on the method name. If not, the test will fail:

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

3.1 新版功能.

assertRegex(text, regex, msg=None)?
assertNotRegex(text, regex, msg=None)?: 測試一個 regex 是否匹配文本。如果不匹配，錯誤信息中將包含匹配模式和 文本*（或部分匹配失敗的 *文本）。regex 可以是正則表達式對象或能夠用于 re.search() 的包含正則表達式的字符串。

3.1 新版功能: 以方法名``assertRegexpMatches``添加。

在 3.2 版更改: 方法 assertRegexpMatches() 已被改名為 assertRegex()。

3.2 新版功能: assertNotRegex()

3.5 新版功能: assertNotRegexpMatches 這個名字是 assertNotRegex() 的已被棄用的別名。

assertCountEqual(first, second, msg=None)?

Test that sequence first contains the same elements as second, regardless of their order. When they don't, an error message listing the differences between the sequences will be generated.

Duplicate elements are not ignored when comparing first and second. It verifies whether each element has the same count in both sequences. Equivalent to: assertEqual(Counter(list(first)), Counter(list(second))) but works with sequences of unhashable objects as well.

3.2 新版功能.

The assertEqual() method dispatches the equality check for objects of the same type to different type-specific methods. These methods are already implemented for most of the built-in types, but it's also possible to register new methods using addTypeEqualityFunc():

addTypeEqualityFunc(typeobj, function)?: Registers a type-specific method called by assertEqual() to check if two objects of exactly the same typeobj (not subclasses) compare equal. function must take two positional arguments and a third msg=None keyword argument just as assertEqual() does. It must raise self.failureException(msg) when inequality between the first two parameters is detected -- possibly providing useful information and explaining the inequalities in details in the error message.

3.1 新版功能.

以下是 assertEqual() 自動選用的不同類型的比較方法。一般情況下不需要直接在測試中調用這些方法。

Method	用作比較	New in
`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)`	元組	3.1
`assertSetEqual(a, b)`	集合	3.1
`assertDictEqual(a, b)`	字典	3.1

assertMultiLineEqual(first, second, msg=None)?: Test that the multiline string first is equal to the string second. When not equal a diff of the two strings highlighting the differences will be included in the error message. This method is used by default when comparing strings with assertEqual().

3.1 新版功能.

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

Tests that two sequences are equal. If a seq_type is supplied, both first and second must be instances of seq_type or a failure will be raised. If the sequences are different an error message is constructed that shows the difference between the two.

This method is not called directly by assertEqual(), but it's used to implement assertListEqual() and assertTupleEqual().

3.1 新版功能.

assertListEqual(first, second, msg=None)?
assertTupleEqual(first, second, msg=None)?: Tests that two lists or tuples are equal. If not, an error message is constructed that shows only the differences between the two. An error is also raised if either of the parameters are of the wrong type. These methods are used by default when comparing lists or tuples with assertEqual().

3.1 新版功能.

assertSetEqual(first, second, msg=None)?

Tests that two sets are equal. If not, an error message is constructed that lists the differences between the sets. This method is used by default when comparing sets or frozensets with assertEqual().

Fails if either of first or second does not have a set.difference() method.

3.1 新版功能.

assertDictEqual(first, second, msg=None)?: Test that two dictionaries are equal. If not, an error message is constructed that shows the differences in the dictionaries. This method will be used by default to compare dictionaries in calls to assertEqual().

3.1 新版功能.

Finally the TestCase provides the following methods and attributes:

fail(msg=None)?: Signals a test failure unconditionally, with msg or None for the error message.

failureException?: This class attribute gives the exception raised by the test method. If a test framework needs to use a specialized exception, possibly to carry additional information, it must subclass this exception in order to "play fair" with the framework. The initial value of this attribute is AssertionError.

longMessage?

This class attribute determines what happens when a custom failure message is passed as the msg argument to an assertXYY call that fails. True is the default value. In this case, the custom message is appended to the end of the standard failure message. When set to False, the custom message replaces the standard message.

The class setting can be overridden in individual test methods by assigning an instance attribute, self.longMessage, to True or False before calling the assert methods.

The class setting gets reset before each test call.

3.1 新版功能.

maxDiff?

This attribute controls the maximum length of diffs output by assert methods that report diffs on failure. It defaults to 80*8 characters. Assert methods affected by this attribute are assertSequenceEqual() (including all the sequence comparison methods that delegate to it), assertDictEqual() and assertMultiLineEqual().

Setting maxDiff to None means that there is no maximum length of diffs.

3.2 新版功能.

Testing frameworks can use the following methods to collect information on the test:

countTestCases()?: Return the number of tests represented by this test object. For TestCase instances, this will always be 1.

defaultTestResult()?

Return an instance of the test result class that should be used for this test case class (if no other result instance is provided to the run() method).

For TestCase instances, this will always be an instance of TestResult; subclasses of TestCase should override this as necessary.

id()?: Return a string identifying the specific test case. This is usually the full name of the test method, including the module and class name.

shortDescription()?: Returns a description of the test, or None if no description has been provided. The default implementation of this method returns the first line of the test method's docstring, if available, or None.

在 3.1 版更改: In 3.1 this was changed to add the test name to the short description even in the presence of a docstring. This caused compatibility issues with unittest extensions and adding the test name was moved to the TextTestResult in Python 3.2.

addCleanup(function, *args, **kwargs)?

Add a function to be called after tearDown() to cleanup resources used during the test. 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 addCleanup() when they are added.

If setUp() fails, meaning that tearDown() is not called, then any cleanup functions added will still be called.

3.1 新版功能.

doCleanups()?

This method is called unconditionally after tearDown(), or after setUp() if setUp() raises an exception.

It is responsible for calling all the cleanup functions added by addCleanup(). If you need cleanup functions to be called prior to tearDown() then you can call doCleanups() yourself.

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

3.1 新版功能.

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 版后已移除: The fail* aliases listed in the second column have been deprecated.

3.2 版后已移除: The assert* aliases listed in the third column have been deprecated.

3.2 版后已移除: assertRegexpMatches and assertRaisesRegexp have been renamed to assertRegex() and assertRaisesRegex().

3.5 版后已移除: 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.

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

在 3.4 版更改: 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 新版功能.

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.

注解

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.

在 3.2 版更改: Support for load_tests added.

在 3.5 版更改: 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.

在 3.5 版更改: 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 新版功能.

在 3.4 版更改: Modules that raise SkipTest on import are recorded as skips, not errors. Discovery works for namespace packages. 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.

在 3.5 版更改: 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 新版功能.

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 新版功能.

expectedFailures?: A list containing 2-tuples of TestCase instances and strings holding formatted tracebacks. Each tuple represents an expected failure 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 新版功能.

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

3.2 新版功能.

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

3.5 新版功能.

wasSuccessful()?: Return True if all tests run so far have passed, otherwise returns False.

在 3.4 版更改: 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 新版功能.

stopTestRun()?: Called once after all tests are executed.

3.1 新版功能.

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, 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 新版功能.

class unittest.TextTestResult(stream, descriptions, verbosity)?: A concrete implementation of TestResult used by the TextTestRunner.

3.2 新版功能: 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.

在 3.2 版更改: Added the warnings argument.

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

在 3.5 版更改: 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.

在 3.1 版更改: The exit parameter was added.

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

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

load_tests Protocol?

3.2 新版功能.

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

在 3.5 版更改: 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.

信號處理?

3.2 新版功能.

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):
    ...

`unittest` --- 單元測試框架?

基本實例?

命令行界面?

命令行選項?

探索性測試?

組織你的測試代碼?

復用已有的測試代碼?

跳過測試與預計的失敗?

Distinguishing test iterations using subtests?

類與函數?

測試用例?

Deprecated aliases?

Grouping tests?

Loading and running tests?

load_tests Protocol?

Class and Module Fixtures?

setUpClass and tearDownClass?

setUpModule and tearDownModule?

信號處理?

目錄

上一個主題

下一個主題

本頁

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

unittest --- 單元測試框架?

基本實例?

命令行界面?

命令行選項?

探索性測試?

組織你的測試代碼?

復用已有的測試代碼?

跳過測試與預計的失敗?

Distinguishing test iterations using subtests?

類與函數?

測試用例?

Deprecated aliases?

Grouping tests?

Loading and running tests?

load_tests Protocol?

Class and Module Fixtures?

setUpClass and tearDownClass?

setUpModule and tearDownModule?

信號處理?

`unittest` --- 單元測試框架?