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unittest 筆記

Python unittest 測試框架發想自 JUnit 並與其他單元測試的框架有類似的味道：

  • 支援自動化測試
  • 測試間共享 setup 與 shutdown 程式碼
  • 每次測試皆是獨立，結果不會受其他測試影響
名詞 解釋
測試夾具 (test fixture) 包含一個或多個被執行的測試，與相關的初始與結束動作。
測試案例 (test case) 個別單元測試，用來檢查特定輸入的反應。
測試套組 (test suite) 由測試案例、測試套組構成，用來集合應該被一起執行的測試。
測試執行 (test runner) 負責執行測試與回報結果。

基本範例

Arithmetic.py:

import unittest

def add(a, b):
    return a + b

def subtract(a, b):
    return a - b

def multiply(a, b):
    return a * b

def divide(a, b):
    return a / b

class TestArithmetic(unittest.TestCase):

    def test_add(self):
        self.assertEqual(add(1, 1), 2)

    def test_subtract(self):
        self.assertEqual(subtract(5, 2), 3)

    def test_multiply(self):
        self.assertEqual(multiply(3, 2), 6)

    def test_divide(self):
        self.assertEqual(divide(3.0, 2), 1.5)

if __name__ == '__main__':
    unittest.main()
  • test_add 測試 add() 函數是否正確運作
  • test_subtract 測試 subtract() 函數是否正確運作
  • test_multiply 測試 multiply() 函數是否正確運作
  • test_divide 測試 divide() 函數是否正確運作
  • if __name__ == '__main__' 判斷是否執行執行，若是則執行測試

執行結果：

$ python Arithmetic.py
....
----------------------------------------------------------------------
Ran 4 tests in 0.000s

OK
/tmp/test$ python Arithmetic.py -v                      # 使用參數 -v 提供測試細節
test_add (__main__.TestArithmetic) ... ok
test_divide (__main__.TestArithmetic) ... ok
test_multiply (__main__.TestArithmetic) ... ok
test_subtract (__main__.TestArithmetic) ... ok

----------------------------------------------------------------------
Ran 4 tests in 0.000s

OK

命令列

TestArithmetic.py:

import unittest

class TestArithmetic(unittest.TestCase):

    def test_add(self):
        self.assertEqual(1 + 1, 2)

    def test_subtrat(self):
        self.assertEqual(5 - 2, 3)

    def test_multiply(self):
        self.assertEqual(2 * 3, 6)

    def test_divide(self):
        self.assertEqual(3.0 / 2, 1.5)

執行結果：

$ python -m unittest -h                                 # 顯示 help message
$ python -m unittest TestArithmetic                     # 測試 TestArithmetic 模組，不含副檔名 (.py)
....
----------------------------------------------------------------------
Ran 4 tests in 0.000s

OK
$ python -m unittest TestArithmetic.TestArithmetic      # 測試 TestArithmetic 模組的 TestArithmetic 類別
....
----------------------------------------------------------------------
Ran 4 tests in 0.000s

OK
$ python -m unittest TestArithmetic.TestArithmetic.test_add # 測試 TestArithmetic 模組的 TestArithmetic 類別的 test_add 測試項目
.
----------------------------------------------------------------------
Ran 1 test in 0.000s

OK
$ python -m unittest -v TestArithmetic                  # 顯示測試細節
test_add (TestArithmetic.TestArithmetic) ... ok
test_divide (TestArithmetic.TestArithmetic) ... ok
test_multiply (TestArithmetic.TestArithmetic) ... ok
test_subtrat (TestArithmetic.TestArithmetic) ... ok

----------------------------------------------------------------------
Ran 4 tests in 0.000s

OK
$ python -m unittest TestArithmetic TestStringMethods   # 測試兩個模組
.......
----------------------------------------------------------------------
Ran 7 tests in 0.000s

OK

測試探索

$ ls
TestArithmetic.py    TestStringMethods.py
$ python -m unittest discover -p "Test*.py"             # 找出 "Test*.py" 的檔案測試
.......
----------------------------------------------------------------------
Ran 7 tests in 0.000s

OK
$ python -m unittest discover -v -p "Test*.py"          # 找出 "Test*.py" 的檔案測試，並顯示測試細節
test_add (TestArithmetic.TestArithmetic) ... ok
test_divide (TestArithmetic.TestArithmetic) ... ok
test_multiply (TestArithmetic.TestArithmetic) ... ok
test_subtrat (TestArithmetic.TestArithmetic) ... ok
test_isupper (TestStringMethods.TestStringMethods) ... ok
test_split (TestStringMethods.TestStringMethods) ... ok
test_upper (TestStringMethods.TestStringMethods) ... ok

----------------------------------------------------------------------
Ran 7 tests in 0.000s

OK

不清楚文件提到的 test suite 怎麼弄，先 pass

重新使用舊測試

(略)

忽略測試與預期的錯誤

testSkip.py:

import unittest
import sys

__version__ = (1, 2)

class TestSkipCase(unittest.TestCase):

    @unittest.skip("demonstrating skipping")
    def test_nothing(self):
        self.fail("shouldn't happen")

    @unittest.skipIf(__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_catchExcept(self):
        try:
            1 / 0
        except:
            raise unittest.SkipTest("skipping because ...")
        self.assertEqual(True)

testExpectedFailure.py:

import unittest

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

測試結果：

$ python -m unittest discover -v -p "test*.py"
test_fail (testExpectedFailure.ExpectedFailureTestCase) ... expected failure
test_catchExcept (testSkip.TestSkipCase) ... skipped 'skipping because ...'
test_format (testSkip.TestSkipCase) ... skipped 'not supported in this library version'
test_nothing (testSkip.TestSkipCase) ... skipped 'demonstrating skipping'
test_windows_support (testSkip.TestSkipCase) ... skipped 'requires Windows'

----------------------------------------------------------------------
Ran 5 tests in 0.001s

OK (skipped=4, expected failures=1)

以下修飾詞 (decorator) 用來忽略或預期失敗：

修飾詞 說明
@unittest.skip(reason) 無條件忽略測試。reason 說明為何要忽略測試
@unittest.skipIf(condition, reason) 如果條件成立，則忽略測試
@unittest.skipUnless(condition, reason) 除非條件成立，否則忽略測試
@unittest.expectedFailure 標記測試為預期錯誤。執行時如果測試失敗，結果不算失敗
exception unittest.SkipTest(reason) 產生例外，忽略測試

測試方法

方法 檢查
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
assertIsNot(a, b) a is not b
assertIsNone(x) x is None
assertIsNotNone(x) x is not None
assertIn(a, b) a in b
assertNotIn(a, b) a not in b
assertIsInstance(a, b) isinstance(a, b)
assertNotIsInstance(a, b) not isinstance(a, b)

Grouping tests

class unittest.TestSuite(tests=())

== TBC ==

參考