Rediger

Del via

MSTEST0006: Avoid [ExpectedException]

  • Artikel
Property Value
Rule ID MSTEST0006
Title Avoid [ExpectedException]
Category Design
Fix is breaking or non-breaking Non-breaking
Enabled by default Yes
Default severity Info
Introduced in version 3.2.0
Is there a code fix Yes, starting with 3.7.0

Cause

A method is marked with the [ExpectedException] attribute.

Rule description

Prefer Assert.ThrowsException or Assert.ThrowsExceptionAsync (or Assert.ThrowsExactly/Assert.Throws or Assert.ThrowsExactlyAsync/Assert.ThrowsAsync if using MSTest 3.8 and later) over the [ExpectedException] attribute as it ensures that only the expected line of code throws the expected exception, instead of acting on the whole body of the test. The assert APIs also provide more flexibility and allow you to assert extra properties of the exception.

[TestClass]
public class TestClass
{
    [TestMethod]
    [ExpectedException(typeof(InvalidOperationException))] // Violation
    public void TestMethod()
    {
        // Arrange
        var person = new Person
        {
            FirstName = "John", 
            LastName = "Doe",
        };
        person.SetAge(-1);

        // Act
        person.GrowOlder();
    }
}

How to fix violations

Replace the usage of the [ExpectedException] attribute by a call to Assert.ThrowsException or Assert.ThrowsExceptionAsync (or Assert.ThrowsExactly/Assert.Throws or Assert.ThrowsExactlyAsync/Assert.ThrowsAsync if using MSTest 3.8 and later).

[TestClass]
public class TestClass
{
    [TestMethod]
    public void TestMethod()
    {
        // Arrange
        var person = new Person
        {
            FirstName = "John", 
            LastName = "Doe",
        };
        person.SetAge(-1);

        // Act
        Assert.ThrowsExactly(() => person.GrowOlder());
    }
}

When to suppress warnings

It is safe to suppress this diagnostic when the method is a one-liner.

[TestClass]
public class TestClass
{
    [TestMethod]
    [ExpectedException(typeof(ArgumentNullException))]
    public void TestMethod()
    {
        new Person(null);
    }
}

Suppress a warning

If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.

#pragma warning disable MSTEST0006
// The code that's violating the rule is on this line.
#pragma warning restore MSTEST0006

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}]
dotnet_diagnostic.MSTEST0006.severity = none

For more information, see How to suppress code analysis warnings.