Fix MSTEST0017 false positive when both actual/expected are constants (#4460) (#4510)

Author: Evangelink

src/Analyzers/MSTest.Analyzers/AssertionArgsShouldBePassedInCorrectOrderAnalyzer.cs

@@ -57,6 +57,9 @@ public override void Initialize(AnalysisContext context)
         });
     }
 
+    private static bool IsConstant(IArgumentOperation argumentOperation)
+        => argumentOperation.Value.ConstantValue.HasValue;
+
     private static void AnalyzeOperation(OperationAnalysisContext context, INamedTypeSymbol assertSymbol)
     {
         var invocationOperation = (IInvocationOperation)context.Operation;
@@ -69,9 +72,10 @@ private static void AnalyzeOperation(OperationAnalysisContext context, INamedTyp
             return;
         }
 
-        // If the actual value is a constant or a literal, then the arguments are in the wrong order.
-        if (actualArgument.Value.Kind == OperationKind.Literal
-            || actualArgument.Value.ConstantValue.HasValue)
+        // If the actual value is a constant or a literal and expected is not, then the arguments are in the wrong order.
+        // Note that we don't report if both are literals or constants, as there is no real fix for this.
+        // If both are literals or constants, the assert will always pass or always fail.
+        if (IsConstant(actualArgument) && !IsConstant(expectedArgument))
         {
             context.ReportDiagnostic(invocationOperation.CreateDiagnostic(Rule));
             return;

test/UnitTests/MSTest.Analyzers.UnitTests/AssertionArgsShouldBePassedInCorrectOrderAnalyzerTests.cs

@@ -161,6 +161,27 @@ await VerifyCS.VerifyCodeFixAsync(
             fixedCode);
     }
 
+    public async Task WhenBothAreLiterals_NoDiagnostic()
+    {
+        string code = """
+            using Microsoft.VisualStudio.TestTools.UnitTesting;
+            using System.Collections.Generic;
+
+            [TestClass]
+            public class MyTestClass
+            {
+                [TestMethod]
+                public void NonCompliant()
+                {
+                    Assert.AreEqual(0, 0);
+                    Assert.AreEqual(0, 1);
+                }
+            }
+            """;
+
+        await VerifyCS.VerifyCodeFixAsync(code, code);
+    }
+
     public async Task LiteralUsingNamedArgument()
     {
         string code = """