MSTEST0058: Avoid assertions in catch blocks

Cause

A test method contains assertion statements within a catch block.

Rule description

Placing assertions in catch blocks is an anti-pattern that can lead to confusing test results and makes tests harder to understand. When an exception is thrown, the catch block executes, and the assertion runs. However, if no exception is thrown, the catch block never executes, potentially giving false confidence that the test passed.

Instead, use Assert.Throws or similar methods to verify that expected exceptions are thrown. This makes the test intent clearer and ensures proper test behavior.

[TestClass]
public class TestClass
{
    [TestMethod]
    public void TestMethod()
    {
        try
        {
            // Code that might throw.
            DoSomethingThatMightThrow();
        }
        catch (Exception ex)
        {
            Assert.AreEqual("Expected error message", ex.Message); // Violation
        }
    }
}

How to fix violations

Use Assert.Throws, Assert.ThrowsExactly or related assertion methods to test for exceptions.

[TestClass]
public class TestClass
{
    [TestMethod]
    public void TestMethod_ThrowsExceptionWithExpectedMessage()
    {
        InvalidOperationException exception = Assert.Throws<InvalidOperationException>(() => DoSomethingThatMightThrow());
        Assert.AreEqual("Expected error message", exception.Message);
    }
}

When to suppress warnings

You might suppress this warning if you have a legitimate need to catch an exception and perform complex validation that cannot be easily expressed using standard assertion methods. However, consider refactoring your test to use more explicit exception assertions first.

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 MSTEST0058
// The code that's violating the rule is on this line.
#pragma warning restore MSTEST0058

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

[*.{cs,vb}]
dotnet_diagnostic.MSTEST0058.severity = none

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