MSTEST0032: Always pass assertions

src/Analyzers/MSTest.Analyzers/PreferAssertFailOverAlwaysFalseConditionsAnalyzer.cs

@@ -70,7 +70,7 @@ private static void AnalyzeOperation(OperationAnalysisContext context, INamedTyp
         var operation = (IInvocationOperation)context.Operation;
 
         if (assertSymbol.Equals(operation.TargetMethod.ContainingType, SymbolEqualityComparer.Default) &&
-        IsAlwaysFalse(operation, nullableSymbol))
+            IsAlwaysFalse(operation, nullableSymbol))
         {
             context.ReportDiagnostic(operation.CreateDiagnostic(Rule, operation.TargetMethod.Name));
         }
@@ -84,22 +84,16 @@ private static bool IsAlwaysFalse(IInvocationOperation operation, INamedTypeSymb
             "AreEqual" => GetEqualityStatus(operation, ExpectedParameterName) == EqualityStatus.NotEqual,
             "AreNotEqual" => GetEqualityStatus(operation, NotExpectedParameterName) == EqualityStatus.Equal,
             "IsNotNull" => GetValueArgument(operation) is { Value.ConstantValue: { HasValue: true, Value: null } },
-            "IsNull" => CheckIsNull(operation, nullableSymbol),
+            "IsNull" => GetValueArgument(operation) is { } valueArgumentOperation && IsNotNullableType(valueArgumentOperation, nullableSymbol),
             _ => false,
         };
 
-    private static bool CheckIsNull(IInvocationOperation operation, INamedTypeSymbol? nullableSymbol)
+    private static bool IsNotNullableType(IArgumentOperation valueArgumentOperation, INamedTypeSymbol? nullableSymbol)
     {
-        if (nullableSymbol is null)
-        {
-            return false;
-        }
-
-        IArgumentOperation? valueArg = GetValueArgument(operation);
-        ITypeSymbol? valueArgType = valueArg?.Value.GetReferencedMemberOrLocalOrParameter().GetReferencedMemberOrLocalOrParameter();
-
-        return !SymbolEqualityComparer.IncludeNullability.Equals(valueArgType?.OriginalDefinition, nullableSymbol)
-            && valueArgType?.NullableAnnotation != NullableAnnotation.Annotated;
+        ITypeSymbol? valueArgType = valueArgumentOperation.Value.GetReferencedMemberOrLocalOrParameter().GetReferencedMemberOrLocalOrParameter();
+        return valueArgType is not null
+            && valueArgType.NullableAnnotation == NullableAnnotation.NotAnnotated
+            && !SymbolEqualityComparer.IncludeNullability.Equals(valueArgType.OriginalDefinition, nullableSymbol);
     }
 
     private static IArgumentOperation? GetArgumentWithName(IInvocationOperation operation, string name)

test/UnitTests/MSTest.Analyzers.UnitTests/PreferAssertFailOverAlwaysFalseConditionsAnalyzerTests.cs

@@ -14,7 +14,7 @@ public async Task WhenIsNullAssertion_ValueParameterIsNullable_NoDiagnostic()
     {
         string code = """
             using Microsoft.VisualStudio.TestTools.UnitTesting;
-
+            #nullable enable
             [TestClass]
             public class MyTestClass
             {
@@ -34,7 +34,7 @@ public async Task WhenIsNullAssertion_ValueParameterIsNotNullable_Diagnostic()
     {
         string code = """
             using Microsoft.VisualStudio.TestTools.UnitTesting;
-
+            #nullable enable
             [TestClass]
             public class MyTestClass
             {
@@ -54,7 +54,7 @@ public async Task WhenIsNullAssertion_ValueParameterAsPropertySymbolIsNotNullabl
     {
         string code = """
             using Microsoft.VisualStudio.TestTools.UnitTesting;
-
+            #nullable enable
             [TestClass]
             public class MyTestClass
             {
@@ -75,7 +75,7 @@ public async Task WhenIsNullAssertion_ValueParameterAsPropertySymbolIsNullable_N
     {
         string code = """
             using Microsoft.VisualStudio.TestTools.UnitTesting;
-
+            #nullable enable
             [TestClass]
             public class MyTestClass
             {
@@ -96,7 +96,7 @@ public async Task WhenIsNullAssertion_ValueParameterAsReferenceObjectIsNotNullab
     {
         string code = """
             using Microsoft.VisualStudio.TestTools.UnitTesting;
-
+            #nullable enable
             [TestClass]
             public class TestClass
             {
@@ -117,6 +117,30 @@ public class ObjectClass
         await VerifyCS.VerifyAnalyzerAsync(code);
     }
 
+    public async Task WhenIsNullAssertion_ValueParameterAsReferenceObjectIsNotNullable_WithoutEnableNullable_NoDiagnostic()
+    {
+        string code = """
+            using Microsoft.VisualStudio.TestTools.UnitTesting;
+            [TestClass]
+            public class TestClass
+            {
+                [TestMethod]
+                public void Test()
+                {
+                    ObjectClass obj = new ObjectClass();
+                    Assert.IsNull(obj);
+                }
+            }
+
+            public class ObjectClass
+            {
+
+            }
+            """;
+
+        await VerifyCS.VerifyAnalyzerAsync(code);
+    }
+
     public async Task WhenIsNullAssertion_ValueParameterAsReferenceObjectIsNullable_NoDiagnostic()
     {
         string code = """

test/UnitTests/MSTest.Analyzers.UnitTests/testsbaseline.txt

@@ -153,6 +153,7 @@ MSTest.Analyzers.UnitTests.MSTest.Analyzers.Test.PreferAssertFailOverAlwaysFalse
 MSTest.Analyzers.UnitTests.MSTest.Analyzers.Test.PreferAssertFailOverAlwaysFalseConditionsAnalyzerTests.WhenIsNullAssertion_ValueParameterAsReferenceObjectIsNullable_NoDiagnostic()
 MSTest.Analyzers.UnitTests.MSTest.Analyzers.Test.PreferAssertFailOverAlwaysFalseConditionsAnalyzerTests.WhenIsNullAssertion_ValueParameterIsNotNullable_Diagnostic()
 MSTest.Analyzers.UnitTests.MSTest.Analyzers.Test.PreferAssertFailOverAlwaysFalseConditionsAnalyzerTests.WhenIsNullAssertion_ValueParameterIsNullable_NoDiagnostic()
+MSTest.Analyzers.UnitTests.MSTest.Analyzers.Test.PreferAssertFailOverAlwaysFalseConditionsAnalyzerTests.WhenIsNullAssertion_ValueParameterAsReferenceObjectIsNotNullable_WithoutEnableNullable_NoDiagnostic()
 MSTest.Analyzers.UnitTests.MSTest.Analyzers.Test.PreferConstructorOverTestInitializeAnalyzerTests.WhenTestClassHasCtor_NoDiagnostic()
 MSTest.Analyzers.UnitTests.MSTest.Analyzers.Test.PreferConstructorOverTestInitializeAnalyzerTests.WhenTestClassHasTestInitialize_Diagnostic()
 MSTest.Analyzers.UnitTests.MSTest.Analyzers.Test.PreferConstructorOverTestInitializeAnalyzerTests.WhenTestClassHasTestInitializeAndCtor_Diagnostic()