Fix S2187: Rule should not raise an issue when class is abstract

sonaranalyzer-dotnet/src/SonarAnalyzer.CSharp/Rules/TestClassShouldHaveTestMethod.cs

@@ -1,4 +1,4 @@
-/*
+/*
  * SonarAnalyzer for .NET
  * Copyright (C) 2015-2017 SonarSource SA
  * mailto: contact AT sonarsource DOT com
@@ -61,8 +61,10 @@ protected override void Initialize(SonarAnalysisContext context)
                     }
 
                     var classDeclaration = (ClassDeclarationSyntax)c.Node;
-                    var classSymbol = c.SemanticModel.GetDeclaredSymbol(classDeclaration);
+                    var classSymbol = c.SemanticModel.GetDeclaredSymbol(classDeclaration);
+
                     if (classSymbol == null ||
+                        classSymbol.IsAbstract ||
                         !classSymbol.GetAttributes().Any(a => a.AttributeClass.IsAny(HandledTestClassAttributes)))
                     {
                         return;

sonaranalyzer-dotnet/src/Tests/SonarAnalyzer.UnitTest/TestCases/TestClassShouldHaveTestMethod.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using NUnit.Framework;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
@@ -58,4 +58,32 @@ class ClassTest9
         [TestMethod]
         public void Foo() { }
     }
+
+    [TestClass]
+    public abstract class MyCommonCode1
+    {
+    }
+
+    [TestClass]
+    public class MySubCommonCode1 : MyCommonCode1 // Noncompliant
+    {
+    }
+
+    public class MySubCommonCode11 : MyCommonCode1 // Compliant
+    {
+    }
+
+    [TestFixture]
+    public abstract class MyCommonCode2
+    {
+    }
+
+    [TestFixture]
+    public class MySubCommonCode2 : MyCommonCode2 // Noncompliant
+    {
+    }
+
+    public class MySubCommonCode22 : MyCommonCode2 // Compliant
+    {
+    }
 }