Fix S3431 FP: Don't raise if assertions are done in catch or finally

[martin-strecker-sonarsource]

Description

S3431 is raised when [ExpectedException] is used for a test method. Some test methods rely on the logic of uncaught exceptions as the result of the execution. Forcing the developer to use other means than [ExpectedException] can make the test flow difficult to read.

Repro steps

        [TestMethod]
        [ExpectedException(typeof(InvalidOperationException))] // FP. The attribute makes the test method much simpler.
        public void UsingTest()
        {
            try
            {
                Console.ForegroundColor = ConsoleColor.Black;
                using var _ = new ConsoleAlert();
                Assert.AreEqual(ConsoleColor.Red, Console.ForegroundColor);
                throw new InvalidOperationException();
            }
            finally
            {
                Assert.AreEqual(ConsoleColor.Black, Console.ForegroundColor); // We don't care about the exception itself but only about the code flow.
            }
        }

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

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

Expected behavior

S3431 is not raised.

Actual behavior

S3431 is raised.

Known workarounds

The test code could be moved to a local function and the local function could be asserted to throw. This seems cumbersome, given that there is a simple attribute for this kind of situation. The rule should not raise if assertions are done in catch or finally blocks.

Related information

• C#/VB.NET Plugins version: latest

See also this issue on SQ and SonarSource/sonar-scanner-msbuild#1737 (comment)