Michael Foord | 1e68bec | 2012-03-03 22:24:30 +0000 | [diff] [blame] | 1 | ========== |
| 2 | Sentinel |
| 3 | ========== |
| 4 | |
| 5 | |
| 6 | .. currentmodule:: mock |
| 7 | |
| 8 | .. testsetup:: |
| 9 | |
| 10 | class ProductionClass(object): |
| 11 | def something(self): |
| 12 | return self.method() |
| 13 | |
| 14 | class Test(unittest2.TestCase): |
| 15 | def testSomething(self): |
| 16 | pass |
| 17 | self = Test('testSomething') |
| 18 | |
| 19 | |
| 20 | .. data:: sentinel |
| 21 | |
| 22 | The ``sentinel`` object provides a convenient way of providing unique |
| 23 | objects for your tests. |
| 24 | |
| 25 | Attributes are created on demand when you access them by name. Accessing |
| 26 | the same attribute will always return the same object. The objects |
| 27 | returned have a sensible repr so that test failure messages are readable. |
| 28 | |
| 29 | |
| 30 | .. data:: DEFAULT |
| 31 | |
| 32 | The `DEFAULT` object is a pre-created sentinel (actually |
| 33 | `sentinel.DEFAULT`). It can be used by :attr:`~Mock.side_effect` |
| 34 | functions to indicate that the normal return value should be used. |
| 35 | |
| 36 | |
| 37 | Sentinel Example |
| 38 | ================ |
| 39 | |
| 40 | Sometimes when testing you need to test that a specific object is passed as an |
| 41 | argument to another method, or returned. It can be common to create named |
| 42 | sentinel objects to test this. `sentinel` provides a convenient way of |
| 43 | creating and testing the identity of objects like this. |
| 44 | |
| 45 | In this example we monkey patch `method` to return |
| 46 | `sentinel.some_object`: |
| 47 | |
| 48 | .. doctest:: |
| 49 | |
| 50 | >>> real = ProductionClass() |
| 51 | >>> real.method = Mock(name="method") |
| 52 | >>> real.method.return_value = sentinel.some_object |
| 53 | >>> result = real.method() |
| 54 | >>> assert result is sentinel.some_object |
| 55 | >>> sentinel.some_object |
| 56 | sentinel.some_object |
| 57 | |
| 58 | |