26.4. unittest
— 单元测试框架¶
(如果你已经对测试的概念比较熟悉了,你可能想直接跳转到这一部分 断言方法。)
unittest
单元测试框架是受到 JUnit 的启发,与其他语言中的主流单元测试框架有着相似的风格。其支持测试自动化,配置共享和关机代码测试。支持将测试样例聚合到测试集中,并将测试与报告框架独立。
为了实现这些,unittest
通过面向对象的方式支持了一些重要的概念。
- 测试脚手架
test fixture 表示为了开展一项或多项测试所需要进行的准备工作,以及所有相关的清理操作。举个例子,这可能包含创建临时或代理的数据库、目录,再或者启动一个服务器进程。
- 测试用例
一个测试用例是一个独立的测试单元。它检查输入特定的数据时的响应。
unittest
提供一个基类:TestCase
,用于新建测试用例。- 测试套件
test suite 是一系列的测试用例,或测试套件,或两者皆有。它用于归档需要一起执行的测试。
- 测试运行器(test runner)
test runner 是一个用于执行和输出测试结果的组件。这个运行器可能使用图形接口、文本接口,或返回一个特定的值表示运行测试的结果。
参见
doctest
— 文档测试模块另一个风格完全不同的测试模块。
- 简单 Smalltalk 测试:便用模式
Kent Beck 有关使用
unittest
所共享的模式的测试框架的原创论文。- Nose and pytest
Third-party unittest frameworks with a lighter-weight syntax for writing tests. For example,
assert func(10) == 42
.- Python 测试工具分类
一个 Python 测试工具的详细列表,包含测试框架和模拟对象库。
- Python 中的测试 邮件列表
一个讨论 Python 中的测试和测试工具的特别兴趣小组。
包含在源代码分发中的 Tools/unittestgui/unittestgui.py
文件是一个用于显示测试覆盖率和执行情况的 GUI 工具。它的目的是给那些单元测试的新手们提供方便。在生产环境中建议测试应由持续集成系统(continuous integration system)驱动,例如:Buildbot、 Jenkins 或 Hudson。
26.4.1. 基本实例¶
unittest
模块提供了一系列创建和运行测试的工具。这一段落演示了这些工具的一小部分,但也足以满足大部分用户的需求。
这是一段简短的代码,来测试三种字符串方法:
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()
继承 unittest.TestCase
就创建了一个测试样例。上述三个独立的测试是三个类的方法,这些方法的命名都以 test
开头。 这个命名约定告诉测试运行者类的哪些方法表示测试。
每个测试的关键是:调用 assertEqual()
来检查预期的输出; 调用 assertTrue()
或 assertFalse()
来验证一个条件;调用 assertRaises()
来验证抛出了一个特定的异常。使用这些方法而不是 assert
语句是为了让测试运行者能聚合所有的测试结果并产生结果报告。
通过 setUp()
和 tearDown()
方法,可以设置测试开始前与完成后需要执行的指令。 在 组织你的测试代码 中,对此有更为详细的描述。
最后的代码块中,演示了运行测试的一个简单的方法。 unittest.main()
提供了一个测试脚本的命令行接口。当在命令行运行该测试脚本,上文的脚本生成如以下格式的输出:
...
----------------------------------------------------------------------
Ran 3 tests in 0.000s
OK
在调用测试脚本时添加 -v
参数使 unittest.main()
显示更为详细的信息,生成如以下形式的输出:
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、足够满足许多日常测试需求的特性。文档的剩余部分详述该框架的完整特性。
26.4.2. 命令行界面¶
unittest 模块可以通过命令行运行模块、类和独立测试方法的测试:
python -m unittest test_module1 test_module2
python -m unittest test_module.TestClass
python -m unittest test_module.TestClass.test_method
你可以传入模块名、类或方法名或他们的任意组合。
同样的,测试模块可以通过文件路径指定:
python -m unittest tests/test_something.py
这样就可以使用 shell 的文件名补全指定测试模块。所指定的文件仍需要可以被作为模块导入。路径通过去除 ‘.py’ 、把分隔符转换为 ‘.’ 转换为模块名。若你需要执行不能被作为模块导入的测试文件,你需要直接执行该测试文件。
在运行测试时,你可以通过添加 -v 参数获取更详细(更多的冗余)的信息。
python -m unittest -v test_module
当运行时不包含参数,开始 探索性测试
python -m unittest
用于获取命令行选项列表:
python -m unittest -h
在 3.2 版更改: 在早期版本中,只支持运行独立的测试方法,而不支持模块和类。
26.4.2.1. 命令行选项¶
unittest supports these command-line options:
-
-b
,
--buffer
¶
在测试运行时,标准输出流与标准错误流会被放入缓冲区。成功的测试的运行时输出会被丢弃;测试不通过时,测试运行中的输出会正常显示,错误会被加入到测试失败信息。
-
-c
,
--catch
¶
当测试正在运行时, Control-C 会等待当前测试完成,并在完成后报告已执行的测试的结果。当再次按下 Control-C 时,引发平常的
KeyboardInterrupt
异常。See Signal Handling for the functions that provide this functionality.
-
-f
,
--failfast
¶
当出现第一个错误或者失败时,停止运行测试。
-
--locals
¶
在回溯中显示局部变量。
3.2 新版功能: 添加命令行选项 -b
, -c
和 -f
。
3.5 新版功能: 命令行选项 --locals
。
命令行亦可用于探索性测试,以运行一个项目的所有测试或其子集。
26.4.3. 探索性测试¶
3.2 新版功能.
Unittest支持简单的测试搜索。若需要使用探索性测试,所有的测试文件必须是 modules 或 packages (包括 namespace packages )并可从项目根目录导入(即它们的文件名必须是有效的 identifiers )。
探索性测试在 TestLoader.discover()
中实现,但也可以通过命令行使用。它在命令行中的基本用法如下:
cd project_directory
python -m unittest discover
注解
方便起见, python -m unittest
与 python -m unittest discover
等价。如果你需要向探索性测试传入参数,必须显式地使用 discover
子命令。
discover
有以下选项:
-
-v
,
--verbose
¶
更详细地输出结果。
-
-s
,
--start-directory
directory
¶ 开始进行搜索的目录(默认值为当前目录
.
)。
-
-p
,
--pattern
pattern
¶ 用于匹配测试文件的模式(默认为
test*.py
)。
-
-t
,
--top-level-directory
directory
¶ 指定项目的最上层目录(通常为开始时所在目录)。
-s
,-p
和 -t
选项可以按顺序作为位置参数传入。以下两条命令是等价的:
python -m unittest discover -s project_directory -p "*_test.py"
python -m unittest discover project_directory "*_test.py"
正如可以传入路径那样,传入一个包名作为起始目录也是可行的,如 myproject.subpackage.test
。你提供的包名会被导入,它在文件系统中的位置会被作为起始目录。
警告
探索性测试通过导入测试对测试进行加载。在找到所有你指定的开始目录下的所有测试文件后,它把路径转换为包名并进行导入。如 foo/bar/baz.py
会被导入为 foo.bar.baz
。
如果你有一个全局安装的包,并尝试对这个包的副本进行探索性测试,可能会从错误的地方开始导入。如果出现这种情况,测试会输出警告并退出。
如果你使用包名而不是路径作为开始目录,搜索时会假定它导入的是你想要的目录,所以你不会收到警告。
测试模块和包可以通过 load_tests protocol 自定义测试的加载和搜索。
在 3.4 版更改: 探索性测试支持命名空间包( namespace packages )。
26.4.4. 组织你的测试代码¶
单元测试的构建单位是 test cases :独立的、包含执行条件与正确性检查的方案。在 unittest
中,测试用例表示为 unittest.TestCase
的实例。通过编写 TestCase
的子类或使用 FunctionTestCase
编写你自己的测试用例。
一个 TestCase
实例的测试代码必须是完全自含的,因此它可以独立运行,或与其它任意组合任意数量的测试用例一起运行。
TestCase
的最简单的子类需要实现一个测试方法(例如一个命名以 test
开头的方法)以执行特定的测试代码:
import unittest
class DefaultWidgetSizeTestCase(unittest.TestCase):
def test_default_widget_size(self):
widget = Widget('The widget')
self.assertEqual(widget.size(), (50, 50))
可以看到,为了进行测试,我们使用了基类 TestCase
提供的其中一个 assert*()
方法。若测试不通过,将会引发一个带有说明信息的异常,并且 unittest
会将这个测试用例标记为测试不通过。任何其它类型的异常将会被当做错误处理。
可能同时存在多个前置操作相同的测试,我们可以把测试的前置操作从测试代码中拆解出来,并实现测试前置方法 setUp()
。在运行测试时,测试框架会自动地为每个单独测试调用前置方法。
import unittest
class WidgetTestCase(unittest.TestCase):
def setUp(self):
self.widget = Widget('The widget')
def test_default_widget_size(self):
self.assertEqual(self.widget.size(), (50,50),
'incorrect default size')
def test_widget_resize(self):
self.widget.resize(100,150)
self.assertEqual(self.widget.size(), (100,150),
'wrong size after resize')
注解
多个测试运行的顺序由内置字符串排序方法对测试名进行排序的结果决定。
在测试运行时,若 setUp()
方法引发异常,测试框架会认为测试发生了错误,因此测试方法不会被运行。
相似的,我们提供了一个 tearDown()
方法在测试方法运行后进行清理工作。
import unittest
class WidgetTestCase(unittest.TestCase):
def setUp(self):
self.widget = Widget('The widget')
def tearDown(self):
self.widget.dispose()
若 setUp()
成功运行,无论测试方法是否成功,都会运行 tearDown()
。
这样的一个测试代码运行的环境被称为 test fixture 。一个新的 TestCase 实例作为一个测试脚手架,用于运行各个独立的测试方法。在运行每个测试时,setUp()
、tearDown()
和 __init__()
会被调用一次。
建议你根据所测试的功能,将测试用 TestCase 实现集合起来。unittest
为此提供了机制:test suite,以 unittest
的类 TestSuite
为代表。大部分情况下,调用 unittest.main()
即可,并且它会为你集合所有模块的测试用例并执行。
然而,如果你需要自定义你的测试套件的话,你可以参考以下方法组织你的测试:
def suite():
suite = unittest.TestSuite()
suite.addTest(WidgetTestCase('test_default_widget_size'))
suite.addTest(WidgetTestCase('test_widget_resize'))
return suite
if __name__ == '__main__':
runner = unittest.TextTestRunner()
runner.run(suite())
你可以把测试用例和测试套件放在与被测试代码相同的模块中(比如 widget.py
),但将测试代码放在单独的模块中(比如 test_widget.py
)有几个优势。
测试模块可以从命令行被独立调用。
更容易在分发的代码中剥离测试代码。
降低没有好理由的情况下修改测试代码以通过测试的诱惑。
测试代码应比被测试代码更少地被修改。
被测试代码可以更容易地被重构。
对用 C 语言写成的模块无论如何都得单独写成一个模块,为什么不保持一致呢?
如果测试策略发生了改变,没有必要修改源代码。
26.4.5. 复用已有的测试代码¶
一些用户希望直接使用 unittest
运行已有的测试代码,而不需要把已有的每个测试函数转化为一个 TestCase
的子类。
因此, unittest
提供 FunctionTestCase
类。这个 TestCase
的子类可用于打包已有的测试函数,并支持设置前置与后置函数。
假定有一个测试函数:
def testSomething():
something = makeSomething()
assert something.name is not None
# ...
可以创建等价的测试用例如下,其中前置和后置方法是可选的。
testcase = unittest.FunctionTestCase(testSomething,
setUp=makeSomethingDB,
tearDown=deleteSomethingDB)
注解
可以用 FunctionTestCase
快速将现有的测试转换成基于 unittest
的测试,但不推荐。花点时间继承 TestCase
会让以后重构测试无比轻松。
在某些情况下,现有的测试可能是用 doctest
模块编写的。 如果是这样, doctest
提供了一个 DocTestSuite
类,可以从现有基于 doctest
的测试中自动构建 unittest.TestSuite
用例。
26.4.6. 跳过测试与预计的失败¶
3.1 新版功能.
Unittest 支持跳过单个或整组的测试用例。它还支持把测试标注成“预期失败”的测试。这些坏测试会失败,但不会算进 TestResult
的失败里。
Skipping a test is simply a matter of using the skip()
decorator
or one of its conditional variants.
跳过测试的基本用法如下:
class MyTestCase(unittest.TestCase):
@unittest.skip("demonstrating skipping")
def test_nothing(self):
self.fail("shouldn't happen")
@unittest.skipIf(mylib.__version__ < (1, 3),
"not supported in this library version")
def test_format(self):
# Tests that work for only a certain version of the library.
pass
@unittest.skipUnless(sys.platform.startswith("win"), "requires Windows")
def test_windows_support(self):
# windows specific testing code
pass
在啰嗦模式下运行以上测试例子时,程序输出如下:
test_format (__main__.MyTestCase) ... skipped 'not supported in this library version'
test_nothing (__main__.MyTestCase) ... skipped 'demonstrating skipping'
test_windows_support (__main__.MyTestCase) ... skipped 'requires Windows'
----------------------------------------------------------------------
Ran 3 tests in 0.005s
OK (skipped=3)
跳过测试类的写法跟跳过测试方法的写法相似:
@unittest.skip("showing class skipping")
class MySkippedTestCase(unittest.TestCase):
def test_not_run(self):
pass
TestCase.setUp()
也可以跳过测试。可以用于所需资源不可用的情况下跳过接下来的测试。
使用 expectedFailure()
装饰器表明这个测试预计失败。:
class ExpectedFailureTestCase(unittest.TestCase):
@unittest.expectedFailure
def test_fail(self):
self.assertEqual(1, 0, "broken")
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 implement test skipping and expected failures:
-
@
unittest.
skip
(reason)¶ 跳过被此装饰器装饰的测试。 reason 为测试被跳过的原因。
-
@
unittest.
skipIf
(condition, reason)¶ 当 condition 为真时,跳过被装饰的测试。
-
@
unittest.
skipUnless
(condition, reason)¶ 跳过被装饰的测试,除非 condition 为真。
-
@
unittest.
expectedFailure
¶ Mark the test as an expected failure. If the test fails when run, the test is not counted as a failure.
-
exception
unittest.
SkipTest
(reason)¶ 引发此异常以跳过一个测试。
通常来说,你可以使用
TestCase.skipTest()
或其中一个跳过测试的装饰器实现跳过测试的功能,而不是直接引发此异常。
被跳过的测试的 setUp()
和 tearDown()
不会被运行。被跳过的类的 setUpClass()
和 tearDownClass()
不会被运行。被跳过的模组的 setUpModule()
和 tearDownModule()
不会被运行。
26.4.7. 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,以下测试:
class NumbersTest(unittest.TestCase):
def test_even(self):
"""
Test that numbers between 0 and 5 are all even.
"""
for i in range(0, 6):
with self.subTest(i=i):
self.assertEqual(i % 2, 0)
可以得到以下输出:
======================================================================
FAIL: test_even (__main__.NumbersTest) (i=1)
----------------------------------------------------------------------
Traceback (most recent call last):
File "subtests.py", line 32, in test_even
self.assertEqual(i % 2, 0)
AssertionError: 1 != 0
======================================================================
FAIL: test_even (__main__.NumbersTest) (i=3)
----------------------------------------------------------------------
Traceback (most recent call last):
File "subtests.py", line 32, in test_even
self.assertEqual(i % 2, 0)
AssertionError: 1 != 0
======================================================================
FAIL: test_even (__main__.NumbersTest) (i=5)
----------------------------------------------------------------------
Traceback (most recent call last):
File "subtests.py", line 32, in test_even
self.assertEqual(i % 2, 0)
AssertionError: 1 != 0
如果不使用子测试,程序遇到第一次错误之后就会停止。而且因为``i``的值不显示,错误也更难找。
======================================================================
FAIL: test_even (__main__.NumbersTest)
----------------------------------------------------------------------
Traceback (most recent call last):
File "subtests.py", line 32, in test_even
self.assertEqual(i % 2, 0)
AssertionError: 1 != 0
26.4.8. 类与函数¶
本节深入介绍了 unittest
的 API。
26.4.8.1. 测试用例¶
-
class
unittest.
TestCase
(methodName='runTest')¶ Instances of the
TestCase
class represent the logical test units in theunittest
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 ofTestCase
, you will neither change the methodName nor reimplement the defaultrunTest()
method.在 3.2 版更改:
TestCase
can be instantiated successfully without providing a methodName. This makes it easier to experiment withTestCase
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.第一组(用于运行测试的)方法是:
-
setUp
()¶ Method called to prepare the test fixture. This is called immediately before calling the test method; other than
AssertionError
orSkipTest
, 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
orSkipTest
, 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 thesetUp()
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 aclassmethod()
:@classmethod def setUpClass(cls): ...
查看 Class and Module Fixtures 获取更详细的说明。
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 aclassmethod()
:@classmethod def tearDownClass(cls): ...
查看 Class and Module Fixtures 获取更详细的说明。
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 orNone
, a temporary result object is created (by calling thedefaultTestResult()
method) and used. The result object is returned torun()
’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 跳过测试与预计的失败 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 获取更详细的信息。
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
a == b
a != b
bool(x) is True
bool(x) is False
a is b
3.1
a is not b
3.1
x is None
3.1
x is not None
3.1
a in b
3.1
a not in b
3.1
isinstance(a, b)
3.2
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 toassertRaises()
,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 toexpr is True
(useassertIs(expr, True)
for the latter). This method should also be avoided when more specific methods are available (e.g.assertEqual(a, b)
instead ofassertTrue(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
(first, second, msg=None)¶ -
assertNotIn
(first, second, msg=None)¶ Test that first is (or is not) in second.
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, useassertIs(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
fun(*args, **kwds)
raises excfun(*args, **kwds)
raises exc and the message matches regex r3.1
fun(*args, **kwds)
raises warn3.2
fun(*args, **kwds)
raises warn and the message matches regex r3.2
The
with
block logs on logger with minimum level3.4
-
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 byre.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: under the name
assertRaisesRegexp
.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 thefilename
andlineno
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 byre.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 astr
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"
orlogging.ERROR
). The default islogging.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.
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
round(a-b, 7) == 0
round(a-b, 7) != 0
a > b
3.1
a >= b
3.1
a < b
3.1
a <= b
3.1
r.search(s)
3.1
not r.search(s)
3.2
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)¶ 测试一个 regex 是否匹配 文本。如果不匹配,错误信息中将包含匹配模式和 文本*(或部分匹配失败的 *文本)。regex 可以是正则表达式对象或能够用于
re.search()
的包含正则表达式的字符串。3.1 新版功能: under the name
assertRegexpMatches
.在 3.2 版更改: 方法
assertRegexpMatches()
已被改名为assertRegex()
。3.2 新版功能:
assertNotRegex()
3.5 新版功能:
assertNotRegexpMatches
这个名字是assertNotRegex()
的已被弃用的别名。
-
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 usingaddTypeEqualityFunc()
:-
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 asassertEqual()
does. It must raiseself.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()
自动选用的不同类型的比较方法。一般情况下不需要直接在测试中调用这些方法。Method
用作比较
New in
字符串
3.1
序列
3.1
列表
3.1
元组
3.1
集合
3.1
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 implementassertListEqual()
andassertTupleEqual()
.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 toFalse
, 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
orFalse
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()
andassertMultiLineEqual()
.Setting
maxDiff
toNone
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 be1
.
-
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 ofTestResult
; subclasses ofTestCase
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, orNone
.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 intoaddCleanup()
when they are added.If
setUp()
fails, meaning thattearDown()
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 aftersetUp()
ifsetUp()
raises an exception.It is responsible for calling all the cleanup functions added by
addCleanup()
. If you need cleanup functions to be called prior totearDown()
then you can calldoCleanups()
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 aunittest
-based test framework.
26.4.8.1.1. 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
failUnlessEqual
assertEquals
failIfEqual
assertNotEquals
failUnless
assert_
failIf
failUnlessRaises
failUnlessAlmostEqual
assertAlmostEquals
failIfAlmostEqual
assertNotAlmostEquals
assertRegexpMatches
assertNotRegexpMatches
assertRaisesRegexp
3.1 版后已移除: the fail* aliases listed in the second column.
3.2 版后已移除: the assert* aliases listed in the third column.
3.2 版后已移除:
assertRegexpMatches
andassertRaisesRegexp
have been renamed toassertRegex()
andassertRaisesRegex()
.3.5 版后已移除: the
assertNotRegexpMatches
name in favor ofassertNotRegex()
.
26.4.8.2. 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 likeTestCase
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 toTestSuite
instances:-
addTests
(tests)¶ Add all the tests from an iterable of
TestCase
andTestSuite
instances to this test suite.This is equivalent to iterating over tests, calling
addTest()
for each element.
TestSuite
shares the following methods withTestCase
:-
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 beforeTestSuite.run()
must be the same for each call iteration. AfterTestSuite.run()
, callers should not rely on the tests returned by this method unless the caller uses a subclass that overridesTestSuite._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 eachTestCase
afterTestSuite.run()
. Subclasses can restore that behavior by overridingTestSuite._removeTestAtIndex()
.
In the typical usage of a
TestSuite
object, therun()
method is invoked by aTestRunner
rather than by the end-user test harness.-
26.4.8.3. 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; theunittest
module provides an instance that can be shared asunittest.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
-derivedtestCaseClass
.A test case instance is created for each method named by
getTestCaseNames()
. By default these are the method names beginning withtest
. IfgetTestCaseNames()
returns no methods, but therunTest()
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 toload_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 aTestCase
orTestSuite
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 aTestCase
-derived classSampleTestCase
with three test methods (test_one()
,test_two()
, andtest_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 thetest_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
orAttributeError
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 aload_tests
function. If this exists then it will be calledpackage.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 callsloader.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 toloader.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 theloadTestsFrom*()
methods.
-
sortTestMethodsUsing
¶ Function to be used to compare method names when sorting them in
getTestCaseNames()
and all theloadTestsFrom*()
methods.
-
-
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. TheTestCase
andTestSuite
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 theTestResult
object generated by running a set of tests for reporting purposes; aTestResult
instance is returned by theTestRunner.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 theTestCase.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.
-
testsRun
¶ The total number of tests run so far.
-
buffer
¶ If set to true,
sys.stdout
andsys.stderr
will be buffered in betweenstartTest()
andstopTest()
being called. Collected output will only be echoed onto the realsys.stdout
andsys.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 returnsFalse
.在 3.4 版更改: Returns
False
if there were anyunexpectedSuccesses
from tests marked with theexpectedFailure()
decorator.
-
stop
()¶ This method can be called to signal that the set of tests being run should be aborted by setting the
shouldStop
attribute toTrue
.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 provideTestRunner
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’serrors
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’sfailures
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’sskipped
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’sexpectedFailures
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 bysys.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 theTextTestRunner
.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 theTestLoader
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
andImportWarning
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 toNone
.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 byrun()
. It is not intended to be called directly, but can be overridden in subclasses to provide a customTestResult
._makeResult()
instantiates the class or callable passed in theTextTestRunner
constructor as theresultclass
argument. It defaults toTextTestResult
if noresultclass
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
orTestCase
instance. ATestResult
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 ofsys.argv
are used.The testRunner argument can either be a test runner class or an already created instance of it. By default
main
callssys.exit()
with an exit code indicating success or failure of the tests run.The testLoader argument has to be a
TestLoader
instance, and defaults todefaultTestLoader
.main
supports being used from the interactive interpreter by passing in the argumentexit=False
. This displays the result on standard output without callingsys.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 theTestProgram
class. This stores the result of the tests run as theresult
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.
26.4.8.3.1. 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.
26.4.9. 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.
26.4.9.1. 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.
26.4.9.2. 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.
26.4.10. 信号处理¶
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 havestop()
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): ...