前言

在測試用例中，執行完測試用例後，最後一步是判斷測試結果是pass還是fail，自動化測試腳本裏面一般把這種生成測試結果的方法稱為斷言（assert）。

用unittest組件測試用例的時候，斷言的方法還是很多的，下面介紹幾種常用的斷言方法：assertEqual、assertIn、assertTrue

一、簡單案例

1.下面寫了4個case，其中第四個是執行失敗的

# coding:utf-8
import unittest
class Test(unittest.TestCase):
def test01(self):
‘‘‘判斷 a == b ‘‘‘
a = 1
b = 1
self.assertEqual(a, b)

def test02(self):
‘‘‘判斷 a in b ‘‘‘
a = "hello"
b = "hello world!"
self.assertIn(a, b)

def test03(self):
‘‘‘判斷 a is True ‘‘‘
a = True
self.assertTrue(a)

def test04(self):
‘‘‘失敗案例‘‘‘
a = "上海-悠悠"
b = "yoyo"
self.assertEqual(a, b)

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

2.執行結果如下

Failure
Expected :‘\xe4\xb8\x8a\xe6\xb5\xb7-\xe6\x82\xa0\xe6\x82\xa0‘
Actual :‘yoyo‘
<Click to see difference>

Traceback (most recent call last):
File "D:\test\yoyotest\kecheng\test12.py", line 27, in test04
self.assertEqual(a, b)
AssertionError: ‘\xe4\xb8\x8a\xe6\xb5\xb7-\xe6\x82\xa0\xe6\x82\xa0‘ != ‘yoyo‘
3.執行的結果，中文編碼不對，沒正常顯示中文，遇到這種情況，可以自定義異常輸出

二、自定義異常

1.以assertEqual為例分析：

assertEqual(self, first, second, msg=None)
Fail if the two objects are unequal as determined by the ‘==‘
operator.

2.翻譯：如果兩個對象不能相等，就返回失敗，相當於return: first==second

3.這裏除了相比較的兩個參數first和second，還有第三個參數msg=None,這個msg參數就是遇到異常後自定義輸出信息

三、unittest常用的斷言方法

1.assertEqual(self, first, second, msg=None)

--判斷兩個參數相等：first == second

2.assertNotEqual(self, first, second, msg=None)

--判斷兩個參數不相等：first ！= second

3.assertIn(self, member, container, msg=None)

--判斷是字符串是否包含：member in container

4.assertNotIn(self, member, container, msg=None)

--判斷是字符串是否不包含：member not in container

5.assertTrue(self, expr, msg=None)

--判斷是否為真：expr is True

6.assertFalse(self, expr, msg=None)

--判斷是否為假：expr is False

7.assertIsNone(self, obj, msg=None)

--判斷是否為None：obj is None

8.assertIsNotNone(self, obj, msg=None)
--判斷是否不為None：obj is not None

四、unittest所有斷言方法

1.下面是unittest框架支持的所有斷言方法，有興趣的同學可以慢慢看。

| assertAlmostEqual(self, first, second, places=None, msg=None, delta=None)
| Fail if the two objects are unequal as determined by their
| difference rounded to the given number of decimal places
| (default 7) and comparing to zero, or by comparing that the
| between the two objects is more than the given delta.
|
| Note that decimal places (from zero) are usually not the same
| as significant digits (measured from the most signficant digit).
|
| If the two objects compare equal then they will automatically
| compare almost equal.
|
| assertAlmostEquals = assertAlmostEqual(self, first, second, places=None, msg=None, delta=None)
|
| assertDictContainsSubset(self, expected, actual, msg=None)
| Checks whether actual is a superset of expected.
|
| assertDictEqual(self, d1, d2, msg=None)
|
| assertEqual(self, first, second, msg=None)
| Fail if the two objects are unequal as determined by the ‘==‘
| operator.
|
| assertEquals = assertEqual(self, first, second, msg=None)
|
| assertFalse(self, expr, msg=None)
| Check that the expression is false.
|
| assertGreater(self, a, b, msg=None)
| Just like self.assertTrue(a > b), but with a nicer default message.
|
| assertGreaterEqual(self, a, b, msg=None)
| Just like self.assertTrue(a >= b), but with a nicer default message.
|
| assertIn(self, member, container, msg=None)
| Just like self.assertTrue(a in b), but with a nicer default message.
|
| assertIs(self, expr1, expr2, msg=None)
| Just like self.assertTrue(a is b), but with a nicer default message.
|
| assertIsInstance(self, obj, cls, msg=None)
| Same as self.assertTrue(isinstance(obj, cls)), with a nicer
| default message.
|
| assertIsNone(self, obj, msg=None)
| Same as self.assertTrue(obj is None), with a nicer default message.
|
| assertIsNot(self, expr1, expr2, msg=None)
| Just like self.assertTrue(a is not b), but with a nicer default message.
|
| assertIsNotNone(self, obj, msg=None)
| Included for symmetry with assertIsNone.
|
| assertItemsEqual(self, expected_seq, actual_seq, msg=None)
| An unordered sequence specific comparison. It asserts that
| actual_seq and expected_seq have the same element counts.
| Equivalent to::
|
| self.assertEqual(Counter(iter(actual_seq)),
| Counter(iter(expected_seq)))
|
| Asserts that each element has the same count in both sequences.
| Example:
| - [0, 1, 1] and [1, 0, 1] compare equal.
| - [0, 0, 1] and [0, 1] compare unequal.
|
| assertLess(self, a, b, msg=None)
| Just like self.assertTrue(a < b), but with a nicer default message.
|
| assertLessEqual(self, a, b, msg=None)
| Just like self.assertTrue(a <= b), but with a nicer default message.
|
| assertListEqual(self, list1, list2, msg=None)
| A list-specific equality assertion.
|
| Args:
| list1: The first list to compare.
| list2: The second list to compare.
| msg: Optional message to use on failure instead of a list of
| differences.
|
| assertMultiLineEqual(self, first, second, msg=None)
| Assert that two multi-line strings are equal.
|
| assertNotAlmostEqual(self, first, second, places=None, msg=None, delta=None)
| Fail if the two objects are equal as determined by their
| difference rounded to the given number of decimal places
| (default 7) and comparing to zero, or by comparing that the
| between the two objects is less than the given delta.
|
| Note that decimal places (from zero) are usually not the same
| as significant digits (measured from the most signficant digit).
|
| Objects that are equal automatically fail.
|
| assertNotAlmostEquals = assertNotAlmostEqual(self, first, second, places=None, msg=None, delta=None)
|
| assertNotEqual(self, first, second, msg=None)
| Fail if the two objects are equal as determined by the ‘!=‘
| operator.
|
| assertNotEquals = assertNotEqual(self, first, second, msg=None)
|
| assertNotIn(self, member, container, msg=None)
| Just like self.assertTrue(a not in b), but with a nicer default message.
|
| assertNotIsInstance(self, obj, cls, msg=None)
| Included for symmetry with assertIsInstance.
|
| assertNotRegexpMatches(self, text, unexpected_regexp, msg=None)
| Fail the test if the text matches the regular expression.
|
| assertRaises(self, excClass, callableObj=None, *args, **kwargs)
| Fail unless an exception of class excClass is raised
| by callableObj when invoked with arguments args and keyword
| arguments kwargs. If a different type of exception is
| raised, it will not be caught, and the test case will be
| deemed to have suffered an error, exactly as for an
| unexpected exception.
|
| If called with callableObj omitted or None, will return a
| context object used like this::
|
| with self.assertRaises(SomeException):
| do_something()
|
| The context manager keeps a reference to the exception as
| the ‘exception‘ attribute. This allows you to inspect the
| exception after the assertion::
|
| with self.assertRaises(SomeException) as cm:
| do_something()
| the_exception = cm.exception
| self.assertEqual(the_exception.error_code, 3)
|
| assertRaisesRegexp(self, expected_exception, expected_regexp, callable_obj=None, *args, **kwargs)
| Asserts that the message in a raised exception matches a regexp.
|
| Args:
| expected_exception: Exception class expected to be raised.
| expected_regexp: Regexp (re pattern object or string) expected
| to be found in error message.
| callable_obj: Function to be called.
| args: Extra args.
| kwargs: Extra kwargs.
|
| assertRegexpMatches(self, text, expected_regexp, msg=None)
| Fail the test unless the text matches the regular expression.
|
| assertSequenceEqual(self, seq1, seq2, msg=None, seq_type=None)
| An equality assertion for ordered sequences (like lists and tuples).
|
| For the purposes of this function, a valid ordered sequence type is one
| which can be indexed, has a length, and has an equality operator.
|
| Args:
| seq1: The first sequence to compare.
| seq2: The second sequence to compare.
| seq_type: The expected datatype of the sequences, or None if no
| datatype should be enforced.
| msg: Optional message to use on failure instead of a list of
| differences.
|
| assertSetEqual(self, set1, set2, msg=None)
| A set-specific equality assertion.
|
| Args:
| set1: The first set to compare.
| set2: The second set to compare.
| msg: Optional message to use on failure instead of a list of
| differences.
|
| assertSetEqual uses ducktyping to support different types of sets, and
| is optimized for sets specifically (parameters must support a
| difference method).
|
| assertTrue(self, expr, msg=None)
| Check that the expression is true.
|
| assertTupleEqual(self, tuple1, tuple2, msg=None)
| A tuple-specific equality assertion.
|
| Args:
| tuple1: The first tuple to compare.
| tuple2: The second tuple to compare.
| msg: Optional message to use on failure instead of a list of
| differences.

Selenium2+python自動化56-unittest之斷言（assert）【轉載】