Fix S2699 FP: AssertionMethodAttribute is ignored when assertion method is inherited

[killergege]

Description

When writing a test without an explicit assertion but using a method to perform that assertion, S2699 is raised if the method is from a parent class.
SonarLint doesn't seem to report the issue, it is reported only when scanned on the pipeline with SonarScanner

Repro steps

Reports a S2699:

public class ParentTest
{
     [AssertionMethod]
    protected void TestAssert<T>(T ex)
    {
        Assert.That(ex!.ToString(), Is.EqualTo(""));
    }
}

public class ChildTest : ParentTest
{
    [Test]
    public void Test()
    {
        TestAssert(new Exception("Message", new Exception("Inner exception.")));
    }
}

This doesn't report S2699 :

public class ParentTest
{
     [AssertionMethod]
    protected virtual void TestAssert<T>(T ex)
    {
        Assert.That(ex!.ToString(), Is.EqualTo(""));
    }
}

public class ChildTest : ParentTest
{
    [Test]
    public void Test()
    {
        TestAssert(new Exception("Message", new Exception("Inner exception.")));
    }

    [AssertionMethod]
    protected override void TestAssert<T>(T ex)
    {
        base.TestAssert(ex);
    }
}

Expected behavior

When assertion method is inherited, it should be detected as an assertion method.

Actual behavior

When assertion methid is inherited, Sonar reports that the test has no assertion

Known workarounds

Override the parent method and set the assertion attribute on that one, and inside call the parent

Related information

• C#/VB.NET Plugins version : SonarLint for VS2022 v.6.10.0.57359
• Visual Studio version : 2022
• MSBuild / dotnet version : MSBuild version 17.3.2+561848881 / .NET 6
• SonarScanner for .NET version (if used) : SonarScanner for MSBuild 5.8 / SonarScanner 4.7.0.2747
• Operating System: Ubuntu / Windows 10

[martin-strecker-sonarsource]

Thank you for reporting this.
I was able to reproduce the behavior partially in #6528. It is indeed a false positive but as far as I can tell it is only raised if the annotated method is overridden. I was not able to reproduce your original example where the assertion method is not overridden. Maybe this is because ParentTest is defined in another assembly than ChildTest but I didn't test this scenario.
I labeled the issue as False Positive and it was added to our backlog.

[killergege]

I may have simplified the case too much. Indeed, in my "real" case, the parent class is in another assembly.

[martin-strecker-sonarsource]

Peach validation: No new issues found