在单元测试中引发异常时，如何获得100％的覆盖率? [英] How do I obtain 100% coverage when an exception is thrown in a unit test?

问题描述

在 C#中，您可以在默认测试套件中捕获如下异常:

In C# you can catch an exception in the default test suite like this:

[TestMethod]
[ExpectedException(typeof (ArgumentNullException))]
public void TestNullComposite()
{
    IApi api = new Api();
    api.GetDataUsingDataContract(null); // this method throws ArgumentNullException
}

但是，当您分析代码覆盖率时，它说您只得到66.67％的覆盖率，因为最后一个花括号没有被覆盖.

But when you analyze the code coverage, it says that you only get 66.67% coverage because the last curly brace was not covered.

在该单元测试中，我将如何实现100％的覆盖率?

How would I go about achieving 100% coverage on this unit test?

推荐答案

在 NUnit 您有方法 Assert.Throws< Exception>() ，它检查是否抛出了所需的异常.它还会将该异常作为返回值返回，以便您可以根据需要进一步声明:

Within NUnit you have a method Assert.Throws<Exception>(), which checks if the desired exception was thrown. It also returns that exception as return value, so that you could have further assertations if you like:

[Test]
public void Api_GetDataUsingDataContractWithNullParameter_ThrowsArgumentNullException()
{
    var api = new Api();
    var exception = Assert.Throws<ArgumentNullException>(() => api.GetDataUsingDataContract(null));
    Assert.That(exception.Message, Is.Not.Null.Or.Empty);
    Assert.That(exception.Message, Is.StringContaining("source"));
}

由于该方法不会自行抛出，因此您的覆盖率将为100％.

Due to the fact, that the method does not throw by itself, your coverage would be 100%.

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