与 Python 一样，有一种复杂的方法可以提供简单的解决方案。
在这种情况下，我们可以使用元编程、装饰器和各种漂亮的 Python 技巧来获得不错的结果。这是最终测试的样子：
import unittest
# Some magic code will be added here later
class DummyTest(unittest.TestCase):
@for_examples(1, 2)
@for_examples(3, 4)
def test_is_smaller_than_four(self, value):
self.assertTrue(value < 4)
@for_examples((1,2),(2,4),(3,7))
def test_double_of_X_is_Y(self, x, y):
self.assertEqual(2 * x, y)
if __name__ == "__main__":
unittest.main()
执行此脚本时，结果为：
..F...F
======================================================================
FAIL: test_double_of_X_is_Y(3,7)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/xdecoret/Documents/foo.py", line 22, in method_for_example
method(self, *example)
File "/Users/xdecoret/Documents/foo.py", line 41, in test_double_of_X_is_Y
self.assertEqual(2 * x, y)
AssertionError: 6 != 7
======================================================================
FAIL: test_is_smaller_than_four(4)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/Users/xdecoret/Documents/foo.py", line 22, in method_for_example
method(self, *example)
File "/Users/xdecoret/Documents/foo.py", line 37, in test_is_smaller_than_four
self.assertTrue(value < 4)
AssertionError
----------------------------------------------------------------------
Ran 7 tests in 0.001s
FAILED (failures=2)
实现了我们的目标：
- 不显眼：我们照常从 TestCase 派生
- 我们只编写一次参数化测试
- 每个示例值都被视为一个单独的测试
- 装饰器可以堆叠，因此很容易使用示例集（例如，使用函数从示例文件或目录构建值列表）
- 锦上添花的是它适用于任意数量的签名
那么它是如何工作的呢？基本上，装饰器将示例存储在函数的属性中。我们使用元类将每个修饰函数替换为函数列表。我们将 unittest.TestCase 替换为我们的新魔法代码（粘贴在上面的“魔法”注释中）是：
__examples__ = "__examples__"
def for_examples(*examples):
def decorator(f, examples=examples):
setattr(f, __examples__, getattr(f, __examples__,()) + examples)
return f
return decorator
class TestCaseWithExamplesMetaclass(type):
def __new__(meta, name, bases, dict):
def tuplify(x):
if not isinstance(x, tuple):
return (x,)
return x
for methodname, method in dict.items():
if hasattr(method, __examples__):
dict.pop(methodname)
examples = getattr(method, __examples__)
delattr(method, __examples__)
for example in (tuplify(x) for x in examples):
def method_for_example(self, method = method, example = example):
method(self, *example)
methodname_for_example = methodname + "(" + ", ".join(str(v) for v in example) + ")"
dict[methodname_for_example] = method_for_example
return type.__new__(meta, name, bases, dict)
class TestCaseWithExamples(unittest.TestCase):
__metaclass__ = TestCaseWithExamplesMetaclass
pass
unittest.TestCase = TestCaseWithExamples
如果有人想很好地打包这个，或者为 unittest 提出一个补丁，请随意！引用我的名字将不胜感激。
如果您准备好使用框架自省（导入 sys 模块），代码可以变得更简单并完全封装在装饰器中
def for_examples(*parameters):
def tuplify(x):
if not isinstance(x, tuple):
return (x,)
return x
def decorator(method, parameters=parameters):
for parameter in (tuplify(x) for x in parameters):
def method_for_parameter(self, method=method, parameter=parameter):
method(self, *parameter)
args_for_parameter = ",".join(repr(v) for v in parameter)
name_for_parameter = method.__name__ + "(" + args_for_parameter + ")"
frame = sys._getframe(1) # pylint: disable-msg=W0212
frame.f_locals[name_for_parameter] = method_for_parameter
return None
return decorator