可以发现Person_FirstName_Set和Person_FirstName_Set_Invalid的差异很小，我们可以进一步试着通用化：
[TestMethod]
| public void Person_FirstName_Set_Valid() { Person_FirstName_Set("Bob", false); } [TestMethod] public void Person_FirstName_Set_Empty() { Person_FirstName_Set(String.Empty, true); } [TestMethod] public void Person_FirstName_Set_Null() { Person_FirstName_Set(null, true); } public void Person_FirstName_Set(string firstName, bool shouldHaveErrors) { var person = new Person("Adam", "Smith"); var eventAssert = new PropertyChangedEventAssert(person); var errorsChangedAssert = new ErrorsChangedEventAssert(person); var changeAssert = new ChangeAssert(person); Assert.IsFalse(person.IsChanged, "Test setup failed, IsChanged is not false"); Assert.AreEqual("Adam", person.FirstName, "Test setup failed, FirstName is not Adam"); Assert.AreEqual("Smith", person.LastName, "Test setup failed, LastName is not Smith"); person.FirstName = firstName; Assert.AreEqual(firstName, person.FirstName, "FirstName setter failed"); Assert.AreEqual((firstName + " Smith").Trim(), person.FullName, "FullName not updated with FirstName changed"); Assert.AreEqual(true, person.IsChanged, "IsChanged flag was not set when FirstName changed"); eventAssert.Expect("IsChanged"); eventAssert.Expect("FirstName"); eventAssert.Expect("FullName"); if (shouldHaveErrors) { Assert.IsTrue(person.HasErrors, "HasErrors should have remained false"); errorsChangedAssert.ExpectCountEquals(1, "Expected an ErrorsChanged event"); changeAssert.AssertOnlyChangesAre("FirstName", "FullName", "IsChanged", "HasErrors"); } else { errorsChangedAssert.ExpectNothing("Expected no ErrorsChanged events"); changeAssert.AssertOnlyChangesAre("FirstName", "FullName", "IsChanged"); } } |
在测试代码变得令人迷惑之前，我们可以把它通用化什么程度，这里绝对有个限制。但是一个有意义的测试名称，并给每个断言配一个好的描述可以让你的测试更加容易让人理解。
控制变量
目前所有的断言都只考虑到了测试用例的输出。他们假设每个Person对象初始状态已知，然后从此出发进行其他操作。但是如果我们想让测试更具科学性，必须确保我们能控制变量。或者换句话说，我们需要保证，一切在掌握之中。
请看下面一组断言：
| Assert.IsFalse(person.HasErrors, "Test setup failed, HasErrors is not false"); Assert.IsFalse(person.IsChanged, "Test setup failed, IsChanged is not false"); Assert.AreEqual("Adam", person.FirstName, "Test setup failed, FirstName is not Adam"); Assert.AreEqual("Smith", person.LastName, "Test setup failed, LastName is not Smith"); |
