Unittest Framework 简明教程

UnitTest Framework - Assertion

Python 测试框架使用 Python 的内置 assert() 函数，该函数测试特定条件。如果断言失败，则会引发 AssertionError。然后，测试框架会将测试识别为失败。其他异常被视为错误。

Python testing framework uses Python’s built-in assert() function which tests a particular condition. If the assertion fails, an AssertionError will be raised. The testing framework will then identify the test as Failure. Other exceptions are treated as Error.

在 unittest 模块中定义了以下三组断言函数：

The following three sets of assertion functions are defined in unittest module −

Basic Boolean Asserts
Comparative Asserts
Asserts for Collections

基本断言函数评估运算结果是 True 还是 False。所有 assert 方法都接受一个 msg 参数，如果指定，则该参数在失败时用作错误消息。

Basic assert functions evaluate whether the result of an operation is True or False. All the assert methods accept a msg argument that, if specified, is used as the error message on failure.

Sr.No.	Method & Description
1	assertEqual(arg1, arg2, msg = None) Test that arg1 and arg2 are equal. If the values do not compare equal, the test will fail.
2	assertNotEqual(arg1, arg2, msg = None) Test that arg1 and arg2 are not equal. If the values do compare equal, the test will fail.
3	assertTrue(expr, msg = None) Test that expr is true. If false, test fails
4	assertFalse(expr, msg = None) Test that expr is false. If true, test fails
5	assertIs(arg1, arg2, msg = None) Test that arg1 and arg2 evaluate to the same object.
6	assertIsNot(arg1, arg2, msg = None) Test that arg1 and arg2 don’t evaluate to the same object.
7	assertIsNone(expr, msg = None) Test that expr is None. If not None, test fails
8	assertIsNotNone(expr, msg = None) Test that expr is not None. If None, test fails
9	assertIn(arg1, arg2, msg = None) Test that arg1 is in arg2.
10	assertNotIn(arg1, arg2, msg = None) Test that arg1 is not in arg2.
11	assertIsInstance(obj, cls, msg = None) Test that obj is an instance of cls
12	assertNotIsInstance(obj, cls, msg = None) Test that obj is not an instance of cls

上面的部分断言函数在下面的代码中实现 −

Some of the above assertion functions are implemented in the following code −

import unittest

class SimpleTest(unittest.TestCase):
   def test1(self):
      self.assertEqual(4 + 5,9)
   def test2(self):
      self.assertNotEqual(5 * 2,10)
   def test3(self):
      self.assertTrue(4 + 5 == 9,"The result is False")
   def test4(self):
      self.assertTrue(4 + 5 == 10,"assertion fails")
   def test5(self):
      self.assertIn(3,[1,2,3])
   def test6(self):
      self.assertNotIn(3, range(5))

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

当运行上面的脚本时，test2、test4 和 test6 将显示失败，其他将会成功运行。

When the above script is run, test2, test4 and test6 will show failure and others run successfully.

FAIL: test2 (__main__.SimpleTest)
----------------------------------------------------------------------
Traceback (most recent call last):
   File "C:\Python27\SimpleTest.py", line 9, in test2
      self.assertNotEqual(5*2,10)
AssertionError: 10 == 10

FAIL: test4 (__main__.SimpleTest)
----------------------------------------------------------------------
Traceback (most recent call last):
   File "C:\Python27\SimpleTest.py", line 13, in test4
      self.assertTrue(4+5==10,"assertion fails")
AssertionError: assertion fails

FAIL: test6 (__main__.SimpleTest)
----------------------------------------------------------------------
Traceback (most recent call last):
   File "C:\Python27\SimpleTest.py", line 17, in test6
      self.assertNotIn(3, range(5))
AssertionError: 3 unexpectedly found in [0, 1, 2, 3, 4]

----------------------------------------------------------------------
Ran 6 tests in 0.001s

FAILED (failures = 3)

第二组断言函数如下： comparative asserts −

The second set of assertion functions are comparative asserts −

assertAlmostEqual (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),
assertNotAlmostEqual (first, second, places, msg, delta) Test that first and second are not approximately equal by computing the difference, rounding to the given number of decimal places (default 7), and comparing to zero. In both the above functions, 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.
assertGreater (first, second, msg = None) Test that first is greater than second depending on the method name. If not, the test will fail.
assertGreaterEqual (first, second, msg = None) Test that first is greater than or equal to second depending on the method name. If not, the test will fail
assertLess (first, second, msg = None) Test that first is less than second depending on the method name. If not, the test will fail
assertLessEqual (first, second, msg = None) Test that first is less than or equal to second depending upon the method name. If not, the test will fail.
assertRegexpMatches (text, regexp, msg = None) Test that a regexp search matches the text. In case of failure, the error message will include the pattern and the text. regexp may be a regular expression object or a string containing a regular expression suitable for use by re.search().
assertNotRegexpMatches (text, regexp, msg = None) Verifies that a regexp search does not match text. Fails with an error message including the pattern and the part of text that matches. regexp may be a regular expression object or a string containing a regular expression suitable for use by re.search() .

断言函数在以下示例中实现 −

The assertion functions are implemented in the following example −

import unittest
import math
import re

class SimpleTest(unittest.TestCase):
   def test1(self):
      self.assertAlmostEqual(22.0/7,3.14)
   def test2(self):
      self.assertNotAlmostEqual(10.0/3,3)
   def test3(self):
      self.assertGreater(math.pi,3)
   def test4(self):
      self.assertNotRegexpMatches("Tutorials Point (I) Private Limited","Point")

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

上述脚本将 test1 和 test4 报告为失败。在 test1 中，22/7 的除法不在 3.14 的 7 个小数位之内。类似地，由于第二个参数与第一个参数中的文本匹配，test4 导致 AssertionError。

The above script reports test1 and test4 as Failure. In test1, the division of 22/7 is not within 7 decimal places of 3.14. Similarly, since the second argument matches with the text in first argument, test4 results in AssertionError.

=====================================================FAIL: test1 (__main__.SimpleTest)
----------------------------------------------------------------------
Traceback (most recent call last):
   File "asserttest.py", line 7, in test1
      self.assertAlmostEqual(22.0/7,3.14)
AssertionError: 3.142857142857143 != 3.14 within 7 places
================================================================
FAIL: test4 (__main__.SimpleTest)
----------------------------------------------------------------------
Traceback (most recent call last):
   File "asserttest.py", line 13, in test4
      self.assertNotRegexpMatches("Tutorials Point (I) Private Limited","Point")
AssertionError: Regexp matched: 'Point' matches 'Point' in 'Tutorials Point (I)
Private Limited'
----------------------------------------------------------------------

Ran 4 tests in 0.001s

FAILED (failures = 2)

Assert for Collections

这组断言函数旨在与 Python 中的集合数据类型一起使用，例如 List、Tuple、Dictionary 和 Set。

This set of assert functions are meant to be used with collection data types in Python, such as List, Tuple, Dictionary and Set.

Sr.No.	Method & Description
1	assertListEqual (list1, list2, msg = None) Tests that two lists are equal. If not, an error message is constructed that shows only the differences between the two.
2	assertTupleEqual (tuple1, tuple2, msg = None) Tests that two tuples are equal. If not, an error message is constructed that shows only the differences between the two.
3	assertSetEqual (set1, set2, msg = None) Tests that two sets are equal. If not, an error message is constructed that lists the differences between the sets.
4	assertDictEqual (expected, actual, msg = None) Test that two dictionaries are equal. If not, an error message is constructed that shows the differences in the dictionaries.

以下示例实现了上述方法 −

The following example implements the above methods −

import unittest

class SimpleTest(unittest.TestCase):
   def test1(self):
      self.assertListEqual([2,3,4], [1,2,3,4,5])
   def test2(self):
      self.assertTupleEqual((1*2,2*2,3*2), (2,4,6))
   def test3(self):
      self.assertDictEqual({1:11,2:22},{3:33,2:22,1:11})

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

在上例中，test1 和 test3 会显示 AssertionError。错误消息显示了 List 和 Dictionary 对象中的差异。

In the above example, test1 and test3 show AssertionError. Error message displays the differences in List and Dictionary objects.

FAIL: test1 (__main__.SimpleTest)
----------------------------------------------------------------------
Traceback (most recent call last):
   File "asserttest.py", line 5, in test1
      self.assertListEqual([2,3,4], [1,2,3,4,5])
AssertionError: Lists differ: [2, 3, 4] != [1, 2, 3, 4, 5]

First differing element 0:
2
1

Second list contains 2 additional elements.
First extra element 3:
4

- [2, 3, 4]
+ [1, 2, 3, 4, 5]
? +++       +++

FAIL: test3 (__main__.SimpleTest)
----------------------------------------------------------------------
Traceback (most recent call last):
   File "asserttest.py", line 9, in test3
      self.assertDictEqual({1:11,2:22},{3:33,2:22,1:11})
AssertionError: {1: 11, 2: 22} != {1: 11, 2: 22, 3: 33}
- {1: 11, 2: 22}
+ {1: 11, 2: 22, 3: 33}
?              +++++++

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

FAILED (failures = 2)