如何使用 ExpectedException 属性强制执行异常消息

Question

我认为这两个测试应该表现相同，事实上，我在我的项目中使用 MS Test 编写了测试，只是现在发现它并不像 NUnit 那样尊重预期的消息。

NUnit（失败）：

[Test, ExpectedException(typeof(System.FormatException), ExpectedMessage = "blah")]
public void Validate()
{
    int.Parse("dfd");
}

MS 测试（通过）：

[TestMethod, ExpectedException(typeof(System.FormatException), "blah")]
public void Validate()
{
    int.Parse("dfd");
}

无论我给 ms 测试发出什么消息，它都会通过。

如果消息不正确，有什么方法可以让 ms 测试失败吗？我什至可以创建自己的异常属性吗？我宁愿不必为发生这种情况的每个测试编写一个 try catch 块。

Answer 1

我们到处都使用这个属性，并且我们显然误解了第二个参数（我们感到羞耻）。

然而，我们肯定用它来检查异常消息。以下是我们使用此页面中的提示的内容。它不处理全球化或继承的异常类型，但它可以满足我们的需要。同样，目标是简单地 RR 'ExpectedException' 并将其与此类交换。 （糟糕的 ExpectedException 已被密封。）

public class ExpectedExceptionWithMessageAttribute : ExpectedExceptionBaseAttribute
{
    public Type ExceptionType { get; set; }

    public string ExpectedMessage { get; set; }

    public ExpectedExceptionWithMessageAttribute(Type exceptionType)
    {
        this.ExceptionType = exceptionType;
    }

    public ExpectedExceptionWithMessageAttribute(Type exceptionType, string expectedMessage)
    {
        this.ExceptionType = exceptionType;
        this.ExpectedMessage = expectedMessage;
    }

    protected override void Verify(Exception e)
    {
        if (e.GetType() != this.ExceptionType)
        {
            Assert.Fail($"ExpectedExceptionWithMessageAttribute failed. Expected exception type: {this.ExceptionType.FullName}. " +
                $"Actual exception type: {e.GetType().FullName}. Exception message: {e.Message}");
        }

        var actualMessage = e.Message.Trim();
        if (this.ExpectedMessage != null)
        {
            Assert.AreEqual(this.ExpectedMessage, actualMessage);
        }

        Debug.WriteLine($"ExpectedExceptionWithMessageAttribute:{actualMessage}");
    }
}

Answer 2

mstest 第二个参数是测试失败时打印出来的消息。如果抛出 formatException，mstest 将成功。我发现这篇文章可能有用

http://blogs.msdn.com/b/csell/archive/2006/01/13/expectedexception-might-not-be-what-you-ve-expected.aspx

Answer 3

@rcravens 是正确的 - 第二个参数是测试失败时打印的消息。为了解决这个问题，我所做的就是以稍微不同的方式设计我的测试。诚然，我不喜欢这种方法，但它确实有效。

[TestMethod]
public void Validate()
{
    try
    {
        int.Parse("dfd");
    
        // Test fails if it makes it this far
        Assert.Fail("Expected exception was not thrown.");
    }
    catch (ArgumentNullException ex) // <-- Expected Exception class
    {
        Assert.AreEqual("blah", ex.Message);
    }
    catch (Exception ex) // All the other exceptions
    {
        Assert.Fail("Thrown exception was of the wrong type");
    }
}

Answer 4

我通过添加对 contains、不区分大小写和 ResourcesType-ResourceName 组合的支持，扩展了 BlackjacketMack 对我们项目的回答。

用法示例：

public class Foo
{
    public void Bar(string mode)
    {
        if (string.IsNullOrEmpty(mode)) throw new InvalidOperationException(Resources.InvalidModeSpecified);
    }

    public void Bar(int port)
    {
        if (port < 0 || port > Int16.MaxValue) throw new ArgumentOutOfRangeException("port");
    }
}

[TestClass]
class ExampleClass
{
    [TestMethod]
    [ExpectedExceptionWithMessage(typeof(InvalidOperationException), typeof(Samples.Resources), "InvalidModeSpecified")]
    public void Raise_Exception_With_Message_Resource()
    {
        new Foo().Bar(null);
    }

    [TestMethod]
    [ExpectedExceptionWithMessage(typeof(ArgumentOutOfRangeException), "port", true)]
    public void Raise_Exeception_Containing_String()
    {
        new Foo().Bar(-123);
    }
}

这是更新后的类：

public class ExpectedExceptionWithMessageAttribute : ExpectedExceptionBaseAttribute
{
    public Type ExceptionType { get; set; }

    public Type ResourcesType { get; set; }

    public string ResourceName { get; set; }

    public string ExpectedMessage { get; set; }

    public bool Containing { get; set; }

    public bool IgnoreCase { get; set; }

    public ExpectedExceptionWithMessageAttribute(Type exceptionType)
        : this(exceptionType, null)
    {
    }

    public ExpectedExceptionWithMessageAttribute(Type exceptionType, string expectedMessage)
        : this(exceptionType, expectedMessage, false)
    {
    }

    public ExpectedExceptionWithMessageAttribute(Type exceptionType, string expectedMessage, bool containing)
    {
        this.ExceptionType = exceptionType;
        this.ExpectedMessage = expectedMessage;
        this.Containing = containing;
    }

    public ExpectedExceptionWithMessageAttribute(Type exceptionType, Type resourcesType, string resourceName)
        : this(exceptionType, resourcesType, resourceName, false)
    {
    }

    public ExpectedExceptionWithMessageAttribute(Type exceptionType, Type resourcesType, string resourceName, bool containing)
    {
        this.ExceptionType = exceptionType;
        this.ExpectedMessage = ExpectedMessage;
        this.ResourcesType = resourcesType;
        this.ResourceName = resourceName;
        this.Containing = containing;
    }

    protected override void Verify(Exception e)
    {
        if (e.GetType() != this.ExceptionType)
        {
            Assert.Fail(String.Format(
                            "ExpectedExceptionWithMessageAttribute failed. Expected exception type: <{0}>. Actual exception type: <{1}>. Exception message: <{2}>",
                            this.ExceptionType.FullName,
                            e.GetType().FullName,
                            e.Message
                            )
                        );
        }

        var actualMessage = e.Message.Trim();

        var expectedMessage = this.ExpectedMessage;

        if (expectedMessage == null)
        {
            if (this.ResourcesType != null && this.ResourceName != null)
            {
                PropertyInfo resourceProperty = this.ResourcesType.GetProperty(this.ResourceName, BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public);
                if (resourceProperty != null)
                {
                    string resourceValue = null;

                    try
                    {
                        resourceValue = resourceProperty.GetMethod.Invoke(null, null) as string;
                    }
                    finally
                    {
                        if (resourceValue != null)
                        {
                            expectedMessage = resourceValue;
                        }
                        else
                        {
                            Assert.Fail("ExpectedExceptionWithMessageAttribute failed. Could not get resource value. ResourceName: <{0}> ResourcesType<{1}>.",
                            this.ResourceName,
                            this.ResourcesType.FullName);
                        }
                    }
                }
                else
                {
                    Assert.Fail("ExpectedExceptionWithMessageAttribute failed. Could not find static resource property on resources type. ResourceName: <{0}> ResourcesType<{1}>.",
                        this.ResourceName,
                        this.ResourcesType.FullName);
                }
            }
            else
            {
                Assert.Fail("ExpectedExceptionWithMessageAttribute failed. Both ResourcesType and ResourceName must be specified.");
            }
        }

        if (expectedMessage != null)
        {
            StringComparison stringComparison = this.IgnoreCase ? StringComparison.OrdinalIgnoreCase : StringComparison.Ordinal;
            if (this.Containing)
            {
                if (actualMessage == null || actualMessage.IndexOf(expectedMessage, stringComparison) == -1)
                {
                    Assert.Fail(String.Format(
                                    "ExpectedExceptionWithMessageAttribute failed. Expected message: <{0}>. Actual message: <{1}>. Exception type: <{2}>",
                                    expectedMessage,
                                    e.Message,
                                    e.GetType().FullName
                                    )
                                );
                }
            }
            else
            {
                if (!string.Equals(expectedMessage, actualMessage, stringComparison))
                {
                    Assert.Fail(String.Format(
                                    "ExpectedExceptionWithMessageAttribute failed. Expected message to contain: <{0}>. Actual message: <{1}>. Exception type: <{2}>",
                                    expectedMessage,
                                    e.Message,
                                    e.GetType().FullName
                                    )
                                );
                }
            }
        }
    }
}

Answer 5

您可以使用 此项目 中的代码，如 本文 创建一个 ExpectedExceptionMessage 属性，该属性将与 MS Test 配合使用以获得所需的结果。

ms 测试（失败）：

[TestClass]
public class Tests : MsTestExtensionsTestFixture
{
    [TestMethod, ExpectedExceptionMessage(typeof(System.FormatException), "blah")]
    public void Validate()
    {
        int.Parse("dfd");
    }
}

Answer 6

尝试这种现代方式：

[TestMethod]
public async Task DoSmthAsync_WithWrongParam_ThrowHttpRequestException()
{
    var smbdTask = service.DoSmthAsync(/* call params */);

    var exception = await Assert.ThrowsExceptionAsync<HttpRequestException>(() => smbdTask);
    Assert.AreEqual(HttpStatusCode.NotFound, exception.StatusCode);
}

Answer 7

我不久前写过这个，所以也许 VS2012 有更好的方法。

http://dripcode.blogspot.com.au/search?q=exception

Answer 8

试试这个。在此示例中，我有一条问候消息，它显示给定名称的问候消息。当 name 参数为空或 null 时，系统会抛出异常并显示消息。 ExceptionAssert.Throws 在 MsTest 中验证两者。

[TestMethod]
public void Does_Application_Display_Correct_Exception_Message_For_Empty_String()
{
    // Arrange
    var oHelloWorld = new HelloWorld();

    // Act

    // Asset

    ExceptionAssert.Throws<ArgumentException>(() => 
            oHelloWorld.GreetingMessge(""),"Invalid Name, Name can't be empty");
}

[TestMethod]
public void Does_Application_Display_Correct_Exception_Message_For_Null_String()
{
    // Arrange
    var oHelloWorld = new HelloWorld();

    // Act

    // Asset

    ExceptionAssert.Throws<ArgumentNullException>(() => 
        oHelloWorld.GreetingMessge(null), "Invalid Name, Name can't be null");
}