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Code Analyzer for C#

There is a newer version: 10.2.0.105762

Why is this an issue?
It should be clear to a casual reader what code a test is testing and what results are expected. Unfortunately, that’s not usually the case with
the ExpectedException attribute since an exception could be thrown from almost any line in the method.
This rule detects MSTest and NUnit ExpectedException attribute.
Exceptions
This rule ignores:

   single-line tests, since it is obvious in such methods where the exception is expected to be thrown 
   tests when it tests control flow and assertion are present in either a catch or finally clause 

[TestMethod]
[ExpectedException(typeof(InvalidOperationException))]
public void UsingTest()
{
    Console.ForegroundColor = ConsoleColor.Black;
    try
    {
        using var _ = new ConsoleAlert();
        Assert.AreEqual(ConsoleColor.Red, Console.ForegroundColor);
        throw new InvalidOperationException();
    }
    finally
    {
        Assert.AreEqual(ConsoleColor.Black, Console.ForegroundColor); // The exception itself is not relevant for the test.
    }
}

public sealed class ConsoleAlert : IDisposable
{
    private readonly ConsoleColor previous;

    public  ConsoleAlert()
    {
        previous = Console.ForegroundColor;
        Console.ForegroundColor = ConsoleColor.Red;
    }

    public void Dispose() =>
        Console.ForegroundColor = previous;
}

How to fix it in MSTest
Remove the ExpectedException attribute in favor of using the Assert.ThrowsException
assertion.
Code examples
Noncompliant code example
[TestMethod]
[ExpectedException(typeof(ArgumentNullException))]  // Noncompliant
public void Method_NullParam()
{
    var sut = new MyService();
    sut.Method(null);
}

Compliant solution
[TestMethod]
public void Method_NullParam()
{
    var sut = new MyService();
    Assert.ThrowsException<ArgumentNullException>(() => sut.Method(null));
}

How to fix it in NUnit
Remove the ExpectedException attribute in favor of using the Assert.Throws assertion.
Code examples
Noncompliant code example
[Test]
[ExpectedException(typeof(ArgumentNullException))]  // Noncompliant
public void Method_NullParam()
{
    var sut = new MyService();
    sut.Method(null);
}

Compliant solution
[Test]
public void Method_NullParam()
{
    var sut = new MyService();
    Assert.Throws<ArgumentNullException>(() => sut.Method(null));
}

Resources
Documentation

   Microsoft Learn - Assert.ThrowsException
  Method 
   Microsoft Learn - ExpectedExceptionAttribute Class 
   NUnit - Assert.Throws 
   NUnit - ExpectedExceptionAttribute