`unittest` --- 單元測試框架¶

（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: 一個 test fixture 代表執行一個或多個測試所需要的準備，以及其他相關清理操作，例如可以是建立臨時性的或是代理用 (proxy) 資料庫、目錄、或是啟動一個伺服器程序。
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: 第三方的單元測試框架，但在撰寫測試時使用更輕量的語法。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。

The script Tools/unittestgui/unittestgui.py in the Python source distribution is a GUI tool for test discovery and execution. This is intended largely for ease of use for those new to unit testing. For production environments it is recommended that tests be driven by a continuous integration system such as Buildbot, Jenkins, GitHub Actions, or 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。

The setUp() and tearDown() methods allow you to define instructions that will be executed before and after each test method. They are covered in more detail in the section Organizing test code.

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

在 3.11 版的變更: The behavior of returning a value from a test method (other than the default None value), is now deprecated.

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

在 3.2 版的變更: 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 支援以下命令列選項：

-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.

Patterns that contain a wildcard character (*) are matched against the test name using fnmatch.fnmatchcase(); otherwise simple case-sensitive substring matching is used.

Patterns are matched against the fully qualified test method name as imported by the test loader.

For example, -k foo matches foo_tests.SomeTest.test_something, bar_tests.SomeTest.test_foo, but not bar_tests.FooTest.test_something.

--locals¶: 透過 traceback 顯示本地變數。

--durations N¶: Show the N slowest test cases (N=0 for all).

在 3.2 版被加入: 增加命令列模式選項 -b 、 -c 與 -f。

在 3.5 版被加入: 命令列選項 --locals。

在 3.7 版被加入: 命令列選項 -k。

在 3.12 版被加入: 命令列選項 --durations。

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）¶

在 3.2 版被加入.

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，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"

As well as being a path it is possible to pass a package name, for example myproject.subpackage.test, as the start directory. The package name you supply will then be imported and its location on the filesystem will be used as the start directory.

警示

Test discovery loads tests by importing them. Once test discovery has found all the test files from the start directory you specify it turns the paths into package names to import. For example foo/bar/baz.py will be imported as foo.bar.baz.

If you have a package installed globally and attempt test discovery on a different copy of the package then the import could happen from the wrong place. If this happens test discovery will warn you and exit.

If you supply the start directory as a package name rather than a path to a directory then discover assumes that whichever location it imports from is the location you intended, so you will not get the warning.

Test modules and packages can customize test loading and discovery by through the load_tests protocol.

在 3.4 版的變更: Test discovery supports namespace packages for the start directory. Note that you need to specify the top level directory too (e.g. python -m unittest discover -s root/namespace -t root).

在 3.11 版的變更: unittest dropped the namespace packages support in Python 3.11. It has been broken since Python 3.7. Start directory and subdirectories containing tests must be regular package that have __init__.py file.

Directories containing start directory still can be a namespace package. In this case, you need to specify start directory as dotted package name, and target directory explicitly. For example:

# proj/  <-- current directory
#   namespace/
#     mypkg/
#       __init__.py
#       test_mypkg.py

python -m unittest discover -s namespace.mypkg -t .

Organizing test code¶

The basic building blocks of unit testing are test cases --- single scenarios that must be set up and checked for correctness. In unittest, test cases are represented by unittest.TestCase instances. To make your own test cases you must write subclasses of TestCase or use FunctionTestCase.

The testing code of a TestCase instance should be entirely self contained, such that it can be run either in isolation or in arbitrary combination with any number of other test cases.

The simplest TestCase subclass will simply implement a test method (i.e. a method whose name starts with test) in order to perform specific testing code:

import unittest

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

Note that in order to test something, we use one of the assert* methods provided by the TestCase base class. If the test fails, an exception will be raised with an explanatory message, and unittest will identify the test case as a failure. Any other exceptions will be treated as errors.

Tests can be numerous, and their set-up can be repetitive. Luckily, we can factor out set-up code by implementing a method called setUp(), which the testing framework will automatically call for every single test we run:

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

The order in which the various tests will be run is determined by sorting the test method names with respect to the built-in ordering for strings.

If the setUp() method raises an exception while the test is running, the framework will consider the test to have suffered an error, and the test method will not be executed.

Similarly, we can provide a tearDown() method that tidies up after the test method has been run:

import unittest

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

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

If setUp() succeeded, tearDown() will be run whether the test method succeeded or not.

Such a working environment for the testing code is called a test fixture. A new TestCase instance is created as a unique test fixture used to execute each individual test method. Thus setUp(), tearDown(), and __init__() will be called once per test.

It is recommended that you use TestCase implementations to group tests together according to the features they test. unittest provides a mechanism for this: the test suite, represented by unittest's TestSuite class. In most cases, calling unittest.main() will do the right thing and collect all the module's test cases for you and execute them.

However, should you want to customize the building of your test suite, you can do it yourself:

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())

You can place the definitions of test cases and test suites in the same modules as the code they are to test (such as widget.py), but there are several advantages to placing the test code in a separate module, such as test_widget.py:

The test module can be run standalone from the command line.
The test code can more easily be separated from shipped code.
There is less temptation to change test code to fit the code it tests without a good reason.
Test code should be modified much less frequently than the code it tests.
Tested code can be refactored more easily.
Tests for modules written in C must be in separate modules anyway, so why not be consistent?
If the testing strategy changes, there is no need to change the source code.

Re-using old test code¶

Some users will find that they have existing test code that they would like to run from unittest, without converting every old test function to a TestCase subclass.

For this reason, unittest provides a FunctionTestCase class. This subclass of TestCase can be used to wrap an existing test function. Set-up and tear-down functions can also be provided.

Given the following test function:

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

one can create an equivalent test case instance as follows, with optional set-up and tear-down methods:

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

備註

Even though FunctionTestCase can be used to quickly convert an existing test base over to a unittest-based system, this approach is not recommended. Taking the time to set up proper TestCase subclasses will make future test refactorings infinitely easier.

In some cases, the existing tests may have been written using the doctest module. If so, doctest provides a DocTestSuite class that can automatically build unittest.TestSuite instances from the existing doctest-based tests.

Skipping tests and expected failures¶

在 3.1 版被加入.

Unittest supports skipping individual test methods and even whole classes of tests. In addition, it supports marking a test as an "expected failure," a test that is broken and will fail, but shouldn't be counted as a failure on a TestResult.

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.

Basic skipping looks like this:

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

This is the output of running the example above in verbose mode:

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

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

OK (skipped=4)

Classes can be skipped just like methods:

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

TestCase.setUp() can also skip the test. This is useful when a resource that needs to be set up is not available.

Expected failures use the expectedFailure() decorator.

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))

The following decorators and exception implement test skipping and expected failures:

@unittest.skip(reason)¶: Unconditionally skip the decorated test. reason should describe why the test is being skipped.

@unittest.skipIf(condition, reason)¶: Skip the decorated test if condition is true.

@unittest.skipUnless(condition, reason)¶: Skip the decorated test unless condition is true.

@unittest.expectedFailure¶: Mark the test as an expected failure or error. If the test fails or errors in the test function itself (rather than in one of the test fixture methods) then it will be considered a success. If the test passes, it will be considered a failure.

exception unittest.SkipTest(reason)¶

This exception is raised to skip a test.

Usually you can use TestCase.skipTest() or one of the skipping decorators instead of raising this directly.

Skipped tests will not have setUp() or tearDown() run around them. Skipped classes will not have setUpClass() or tearDownClass() run. Skipped modules will not have setUpModule() or tearDownModule() run.

Distinguishing test iterations using subtests¶

在 3.4 版被加入.

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.

舉例來說，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)

會有以下輸出：

======================================================================
FAIL: test_even (__main__.NumbersTest.test_even) (i=1)
Test that numbers between 0 and 5 are all even.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "subtests.py", line 11, in test_even
    self.assertEqual(i % 2, 0)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 1 != 0

======================================================================
FAIL: test_even (__main__.NumbersTest.test_even) (i=3)
Test that numbers between 0 and 5 are all even.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "subtests.py", line 11, in test_even
    self.assertEqual(i % 2, 0)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 1 != 0

======================================================================
FAIL: test_even (__main__.NumbersTest.test_even) (i=5)
Test that numbers between 0 and 5 are all even.
----------------------------------------------------------------------
Traceback (most recent call last):
  File "subtests.py", line 11, in test_even
    self.assertEqual(i % 2, 0)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 1 != 0

Without using a subtest, execution would stop after the first failure, and the error would be less easy to diagnose because the value of i wouldn't be displayed:

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

Classes and functions¶

This section describes in depth the API of unittest.

Test cases¶

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 版的變更: 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.

Methods in the first group (running the test) are:

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):
    ...

更多細節請見 Class and Module Fixtures。

在 3.2 版被加入.

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):
    ...

更多細節請見 Class and Module Fixtures。

在 3.2 版被加入.

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 版的變更: 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 Skipping tests and expected failures for more information.

在 3.1 版被加入.

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.

更多資訊請見 Distinguishing test iterations using subtests。

在 3.4 版被加入.

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 版的變更: Added the automatic calling of type-specific equality function.

在 3.2 版的變更: 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 are (or are not) the same object.

在 3.1 版被加入.

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

在 3.1 版被加入.

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

在 3.1 版被加入.

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).

在 3.2 版被加入.

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
`assertNoLogs(logger, level)`	The `with` block does not log on logger with minimum level	3.10

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 版的變更: 新增 assertRaises() 可作為情境管理器使用的能力。

在 3.2 版的變更: 新增 exception 屬性。

在 3.3 版的變更: 新增作為情境管理器使用時的 msg 引數。

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')

或是：

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

在 3.1 版被加入: 以 assertRaisesRegexp 為名新增。

在 3.2 版的變更: 重新命名為 assertRaisesRegex()。

在 3.3 版的變更: 新增作為情境管理器使用時的 msg 引數。

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.

在 3.2 版被加入.

在 3.3 版的變更: 新增作為情境管理器使用時的 msg 引數。

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')

或是：

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

在 3.2 版被加入.

在 3.3 版的變更: 新增作為情境管理器使用時的 msg 引數。

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 that were not blocked by a non-propagating descendent logger.

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.

範例：

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'])

在 3.4 版被加入.

assertNoLogs(logger=None, level=None)¶

A context manager to test that no messages are 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.

Unlike assertLogs(), nothing will be returned by the context manager.

在 3.10 版被加入.

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 版的變更: 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"

在 3.1 版被加入.

assertRegex(text, regex, msg=None)¶
assertNotRegex(text, regex, msg=None)¶: Test that a regex search matches (or does not match) text. In case of failure, the error message will include the pattern and the text (or the pattern and the part of text that unexpectedly matched). regex may be a regular expression object or a string containing a regular expression suitable for use by re.search().

在 3.1 版被加入: 以 assertRegexpMatches 為名新增。

在 3.2 版的變更: The method assertRegexpMatches() has been renamed to assertRegex().

在 3.2 版被加入: assertNotRegex()。

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.

在 3.2 版被加入.

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.

在 3.1 版被加入.

The list of type-specific methods automatically used by assertEqual() are summarized in the following table. Note that it's usually not necessary to invoke these methods directly.

Method	Used to compare	New in
`assertMultiLineEqual(a, b)`	strings	3.1
`assertSequenceEqual(a, b)`	sequences	3.1
`assertListEqual(a, b)`	lists	3.1
`assertTupleEqual(a, b)`	tuples	3.1
`assertSetEqual(a, b)`	sets or frozensets	3.1
`assertDictEqual(a, b)`	dicts	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().

在 3.1 版被加入.

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().

在 3.1 版被加入.

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().

在 3.1 版被加入.

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.

在 3.1 版被加入.

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().

在 3.1 版被加入.

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.

在 3.1 版被加入.

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.

在 3.2 版被加入.

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 版的變更: 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.

在 3.1 版被加入.

enterContext(cm)¶: Enter the supplied context manager. If successful, also add its __exit__() method as a cleanup function by addCleanup() and return the result of the __enter__() method.

在 3.11 版被加入.

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.

在 3.1 版被加入.

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

Add a function to be called after tearDownClass() 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 addClassCleanup() when they are added.

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

在 3.8 版被加入.

classmethod enterClassContext(cm)¶: Enter the supplied context manager. If successful, also add its __exit__() method as a cleanup function by addClassCleanup() and return the result of the __enter__() method.

在 3.11 版被加入.

classmethod doClassCleanups()¶

This method is called unconditionally after tearDownClass(), or after setUpClass() if setUpClass() raises an exception.

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.

在 3.8 版被加入.

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

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

在 3.8 版被加入.

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.

coroutine enterAsyncContext(cm)¶: Enter the supplied asynchronous context manager. If successful, also add its __aexit__() method as a cleanup function by addAsyncCleanup() and return the result of the __aenter__() method.

在 3.11 版被加入.

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.

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 版的變更: In earlier versions the TestSuite accessed tests directly rather than through iteration, so overriding __iter__() wasn't sufficient for providing tests.

在 3.4 版的變更: 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 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.

在 3.5 版被加入.

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.

在 3.2 版的變更: Support for load_tests added.

在 3.5 版的變更: Support for a keyword-only argument pattern has been added.

在 3.12 版的變更: The undocumented and unofficial use_load_tests parameter has been removed.

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 版的變更: 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 top_level_dir 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 internally, and used as a default to any nested calls to discover(). That is, if a package's load_tests calls loader.discover(), it does not need to pass this argument.

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

在 3.2 版被加入.

在 3.4 版的變更: Modules that raise SkipTest on import are recorded as skips, not errors.

在 3.4 版的變更: start_dir can be a namespace packages.

在 3.4 版的變更: 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 版的變更: 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.

在 3.11 版的變更: start_dir can not be a namespace packages. It has been broken since Python 3.7 and Python 3.11 officially remove it.

在 3.12.4 版的變更: top_level_dir is only stored for the duration of discover call.

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 -k 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 -k option, simple substring patterns will have to be converted using * wildcards.

This affects all the loadTestsFrom* methods.

在 3.7 版被加入.

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 assert* methods.

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

在 3.1 版被加入.

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.

collectedDurations¶: A list containing 2-tuples of test case names and floats representing the elapsed time of each test which was run.

在 3.12 版被加入.

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.

在 3.2 版被加入.

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

在 3.2 版被加入.

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

在 3.5 版被加入.

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

在 3.4 版的變更: 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.

在 3.1 版被加入.

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

在 3.1 版被加入.

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.

在 3.4 版被加入.

addDuration(test, elapsed)¶: Called when the test case finishes. elapsed is the time represented in seconds, and it includes the execution of cleanup functions.

在 3.12 版被加入.

class unittest.TextTestResult(stream, descriptions, verbosity, *, durations=None)¶: A concrete implementation of TestResult used by the TextTestRunner. Subclasses should accept **kwargs to ensure compatibility as the interface changes.

在 3.2 版被加入.

在 3.12 版的變更: 新增 durations 關鍵字參數。

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, durations=None)¶

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. This behavior can be overridden using Python's -Wd or -Wa options (see Warning control) and leaving warnings to None.

在 3.2 版的變更: 新增 warnings 參數。

在 3.2 版的變更: The default stream is set to sys.stderr at instantiation time rather than import time.

在 3.5 版的變更: 新增 tb_locals 參數。

在 3.12 版的變更: 新增 durations 參數。

_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 (0) or failure (1) of the tests run. An exit code of 5 indicates that no tests were run or skipped.

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 returns an object with the result attribute that contains the result of the tests run as a unittest.TestResult.

在 3.1 版的變更: 新增 exit 參數。

在 3.2 版的變更: The verbosity, failfast, catchbreak, buffer and warnings parameters were added.

在 3.4 版的變更: The defaultTest parameter was changed to also accept an iterable of test names.

load_tests Protocol¶

在 3.2 版被加入.

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

在 3.5 版的變更: 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.

在 3.8 版被加入.

classmethod unittest.enterModuleContext(cm)¶: Enter the supplied context manager. If successful, also add its __exit__() method as a cleanup function by addModuleCleanup() and return the result of the __enter__() method.

在 3.11 版被加入.

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 addModuleCleanup(). 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.

在 3.8 版被加入.

Signal Handling¶

在 3.2 版被加入.

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):
    ...

`unittest` --- 單元測試框架¶

簡單範例¶

命令執行列介面 (Command-Line Interface)¶

命令列模式選項¶

Test Discovery（測試探索）¶

Organizing test code¶

Re-using old test code¶

Skipping tests and expected failures¶

Distinguishing test iterations using subtests¶

Classes and functions¶

Test cases¶

Grouping tests¶

Loading and running tests¶

load_tests Protocol¶

Class and Module Fixtures¶

setUpClass and tearDownClass¶

setUpModule and tearDownModule¶

Signal Handling¶

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unittest --- 單元測試框架¶

簡單範例¶

命令執行列介面 (Command-Line Interface)¶

命令列模式選項¶

Test Discovery（測試探索）¶

Organizing test code¶

Re-using old test code¶

Skipping tests and expected failures¶

Distinguishing test iterations using subtests¶

Classes and functions¶

Test cases¶

Grouping tests¶

Loading and running tests¶

load_tests Protocol¶

Class and Module Fixtures¶

setUpClass and tearDownClass¶

setUpModule and tearDownModule¶

Signal Handling¶

`unittest` --- 單元測試框架¶