MSTEST0036: Add analyzer for when a test member is shadowing another member

src/Analyzers/MSTest.Analyzers/AnalyzerReleases.Unshipped.md

@@ -7,3 +7,4 @@ Rule ID | Category | Severity | Notes
 MSTEST0018 | Usage | Warning | DynamicDataShouldBeValidAnalyzer, [Documentation](https://learn.microsoft.com/dotnet/core/testing/mstest-analyzers/mstest0018)
 MSTEST0034 | Usage | Info | UseClassCleanupBehaviorEndOfClassAnalyzer, [Documentation](https://learn.microsoft.com/dotnet/core/testing/mstest-analyzers/mstest0034)
 MSTEST0035 | Usage | Info | UseDeploymentItemWithTestMethodOrTestClassAnalyzer, [Documentation](https://learn.microsoft.com/dotnet/core/testing/mstest-analyzers/mstest0035)
+MSTEST0036 | Design | Warning | DoNotUseShadowingAnalyzer, [Documentation](https://learn.microsoft.com/dotnet/core/testing/mstest-analyzers/mstest0036)

src/Analyzers/MSTest.Analyzers/DoNotUseShadowingAnalyzer.cs

@@ -0,0 +1,132 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Collections.Immutable;
+
+using Analyzer.Utilities.Extensions;
+
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+using MSTest.Analyzers.Helpers;
+
+namespace MSTest.Analyzers;
+
+/// <summary>
+/// MSTEST0036: <inheritdoc cref="Resources.DoNotUseShadowingTitle"/>.
+/// </summary>
+[DiagnosticAnalyzer(LanguageNames.CSharp, LanguageNames.VisualBasic)]
+public sealed class DoNotUseShadowingAnalyzer : DiagnosticAnalyzer
+{
+    private static readonly LocalizableResourceString Title = new(nameof(Resources.DoNotUseShadowingTitle), Resources.ResourceManager, typeof(Resources));
+    private static readonly LocalizableResourceString Description = new(nameof(Resources.DoNotUseShadowingDescription), Resources.ResourceManager, typeof(Resources));
+    private static readonly LocalizableResourceString MessageFormat = new(nameof(Resources.DoNotUseShadowingMessageFormat), Resources.ResourceManager, typeof(Resources));
+
+    internal static readonly DiagnosticDescriptor DoNotUseShadowingRule = DiagnosticDescriptorHelper.Create(
+        DiagnosticIds.DoNotUseShadowingRuleId,
+        Title,
+        MessageFormat,
+        Description,
+        Category.Design,
+        DiagnosticSeverity.Warning,
+        isEnabledByDefault: true);
+
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; }
+        = ImmutableArray.Create(DoNotUseShadowingRule);
+
+    public override void Initialize(AnalysisContext context)
+    {
+        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
+        context.EnableConcurrentExecution();
+
+        context.RegisterCompilationStartAction(context =>
+        {
+            if (context.Compilation.TryGetOrCreateTypeByMetadataName(WellKnownTypeNames.MicrosoftVisualStudioTestToolsUnitTestingTestClassAttribute, out INamedTypeSymbol? testClassAttributeSymbol))
+            {
+                context.RegisterSymbolAction(
+                    context => AnalyzeSymbol(context, testClassAttributeSymbol),
+                    SymbolKind.NamedType);
+            }
+        });
+    }
+
+    private static void AnalyzeSymbol(SymbolAnalysisContext context, INamedTypeSymbol testClassAttributeSymbol)
+    {
+        var namedTypeSymbol = (INamedTypeSymbol)context.Symbol;
+        if (namedTypeSymbol.TypeKind != TypeKind.Class
+            || !namedTypeSymbol.GetAttributes().Any(attr => SymbolEqualityComparer.Default.Equals(attr.AttributeClass, testClassAttributeSymbol)))
+        {
+            return;
+        }
+
+        Dictionary<string, List<ISymbol>> symbolGroups = GetBaseMembers(namedTypeSymbol);
+        foreach (ISymbol member in namedTypeSymbol.GetMembers())
+        {
+            foreach (ISymbol baseMember in symbolGroups.GetValueOrDefault(member.Name, new List<ISymbol>()))
+            {
+                // Check if the member is shadowing a base class member
+                if (IsMemberShadowing(member, baseMember))
+                {
+                    context.ReportDiagnostic(member.CreateDiagnostic(DoNotUseShadowingRule, member.Name));
+                }
+            }
+        }
+    }
+
+    private static Dictionary<string, List<ISymbol>> GetBaseMembers(INamedTypeSymbol namedTypeSymbol)
+    {
+        Dictionary<string, List<ISymbol>> symbolGroups = new();
+        INamedTypeSymbol? currentType = namedTypeSymbol.BaseType;
+        while (currentType is not null)
+        {
+            foreach (ISymbol member in currentType.GetMembers())
+            {
+                if ((member is IMethodSymbol methodSymbol && (methodSymbol.MethodKind == MethodKind.PropertyGet || methodSymbol.MethodKind == MethodKind.PropertySet))
+                    || member.IsOverride || member.Name == ".ctor")
+                {
+                    continue;
+                }
+
+                if (!symbolGroups.TryGetValue(member.Name, out List<ISymbol>? members))
+                {
+                    members = new List<ISymbol>();
+                    symbolGroups[member.Name] = members;
+                }
+
+                // Add the member to the list
+                members.Add(member);
+            }
+
+            currentType = currentType.BaseType;
+        }
+
+        return symbolGroups;
+    }
+
+    private static bool IsMemberShadowing(ISymbol member, ISymbol baseMember)
+    {
+        // Ensure both members are of the same kind (Method, Property, etc.)
+        if (member.Kind != baseMember.Kind || member.IsOverride)
+        {
+            return false;
+        }
+
+        // Compare methods
+        if (member is IMethodSymbol methodSymbol && baseMember is IMethodSymbol baseMethodSymbol)
+        {
+            return methodSymbol.Name == baseMethodSymbol.Name &&
+                   methodSymbol.Parameters.Length == baseMethodSymbol.Parameters.Length &&
+                   methodSymbol.Parameters.Zip(baseMethodSymbol.Parameters, (p1, p2) =>
+                   SymbolEqualityComparer.Default.Equals(p1.Type, p2.Type)).All(equal => equal);
+        }
+
+        // Compare properties
+        else if (member is IPropertySymbol propertySymbol && baseMember is IPropertySymbol basePropertySymbol)
+        {
+            return propertySymbol.Name == basePropertySymbol.Name &&
+                   SymbolEqualityComparer.Default.Equals(propertySymbol.Type, basePropertySymbol.Type);
+        }
+
+        return false;
+    }
+}

src/Analyzers/MSTest.Analyzers/Helpers/DiagnosticIds.cs

@@ -40,4 +40,5 @@ internal static class DiagnosticIds
     public const string NonNullableReferenceNotInitializedSuppressorRuleId = "MSTEST0033";
     public const string UseClassCleanupBehaviorEndOfClassRuleId = "MSTEST0034";
     public const string UseDeploymentItemWithTestMethodOrTestClassRuleId = "MSTEST0035";
+    public const string DoNotUseShadowingRuleId = "MSTEST0036";
 }

src/Analyzers/MSTest.Analyzers/PublicAPI.Unshipped.txt

@@ -1,4 +1,6 @@
 #nullable enable
+MSTest.Analyzers.DoNotUseShadowingAnalyzer
+MSTest.Analyzers.DoNotUseShadowingAnalyzer.DoNotUseShadowingAnalyzer() -> void
 MSTest.Analyzers.DynamicDataShouldBeValidAnalyzer
 MSTest.Analyzers.DynamicDataShouldBeValidAnalyzer.DynamicDataShouldBeValidAnalyzer() -> void
 MSTest.Analyzers.NonNullableReferenceNotInitializedSuppressor
@@ -7,6 +9,8 @@ MSTest.Analyzers.UseClassCleanupBehaviorEndOfClassAnalyzer
 MSTest.Analyzers.UseClassCleanupBehaviorEndOfClassAnalyzer.UseClassCleanupBehaviorEndOfClassAnalyzer() -> void
 MSTest.Analyzers.UseDeploymentItemWithTestMethodOrTestClassAnalyzer
 MSTest.Analyzers.UseDeploymentItemWithTestMethodOrTestClassAnalyzer.UseDeploymentItemWithTestMethodOrTestClassAnalyzer() -> void
+override MSTest.Analyzers.DoNotUseShadowingAnalyzer.Initialize(Microsoft.CodeAnalysis.Diagnostics.AnalysisContext! context) -> void
+override MSTest.Analyzers.DoNotUseShadowingAnalyzer.SupportedDiagnostics.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.DiagnosticDescriptor!>
 override MSTest.Analyzers.DynamicDataShouldBeValidAnalyzer.Initialize(Microsoft.CodeAnalysis.Diagnostics.AnalysisContext! context) -> void
 override MSTest.Analyzers.DynamicDataShouldBeValidAnalyzer.SupportedDiagnostics.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.DiagnosticDescriptor!>
 override MSTest.Analyzers.NonNullableReferenceNotInitializedSuppressor.ReportSuppressions(Microsoft.CodeAnalysis.Diagnostics.SuppressionAnalysisContext context) -> void

src/Analyzers/MSTest.Analyzers/Resources.resx

@@ -520,4 +520,13 @@ The type declaring these methods should also respect the following rules:
   <data name="TestClassShouldBeValidMessageFormat" xml:space="preserve">
     <value>Test class '{0}' should be valid</value>
   </data>
+  <data name="DoNotUseShadowingDescription" xml:space="preserve">
+    <value>Shadowing test members could cause testing issues (such as NRE).</value>
+  </data>
+  <data name="DoNotUseShadowingMessageFormat" xml:space="preserve">
+    <value>Member '{0}' is already exist in the base class</value>
+  </data>
+  <data name="DoNotUseShadowingTitle" xml:space="preserve">
+    <value>Do not use shadowing</value>
+  </data>
 </root>

src/Analyzers/MSTest.Analyzers/xlf/Resources.cs.xlf

@@ -281,6 +281,21 @@ Typ deklarující tyto metody by měl také respektovat následující pravidla:
         <target state="translated">Neukládejte TestContext ve statickém členu</target>
         <note />
       </trans-unit>
+      <trans-unit id="DoNotUseShadowingDescription">
+        <source>Shadowing test members could cause testing issues (such as NRE).</source>
+        <target state="new">Shadowing test members could cause testing issues (such as NRE).</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingMessageFormat">
+        <source>Member '{0}' is already exist in the base class</source>
+        <target state="new">Member '{0}' is already exist in the base class</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingTitle">
+        <source>Do not use shadowing</source>
+        <target state="new">Do not use shadowing</target>
+        <note />
+      </trans-unit>
       <trans-unit id="DoNotUseSystemDescriptionAttributeDescription">
         <source>'System.ComponentModel.DescriptionAttribute' has no effect in the context of tests and you likely wanted to use 'Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute' instead.</source>
         <target state="translated">System.ComponentModel.DescriptionAttribute nemá v kontextu testů žádný účinek a pravděpodobně jste místo toho chtěli použít Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute.</target>

src/Analyzers/MSTest.Analyzers/xlf/Resources.de.xlf

@@ -283,6 +283,21 @@ Der Typ, der diese Methoden deklariert, sollte auch die folgenden Regeln beachte
         <target state="translated">TestContext nicht in einem statischen Member speichern</target>
         <note />
       </trans-unit>
+      <trans-unit id="DoNotUseShadowingDescription">
+        <source>Shadowing test members could cause testing issues (such as NRE).</source>
+        <target state="new">Shadowing test members could cause testing issues (such as NRE).</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingMessageFormat">
+        <source>Member '{0}' is already exist in the base class</source>
+        <target state="new">Member '{0}' is already exist in the base class</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingTitle">
+        <source>Do not use shadowing</source>
+        <target state="new">Do not use shadowing</target>
+        <note />
+      </trans-unit>
       <trans-unit id="DoNotUseSystemDescriptionAttributeDescription">
         <source>'System.ComponentModel.DescriptionAttribute' has no effect in the context of tests and you likely wanted to use 'Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute' instead.</source>
         <target state="translated">"System.ComponentModel.DescriptionAttribute" hat im Kontext von Tests keine Auswirkungen, und Sie wollten wahrscheinlich stattdessen "Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute" verwenden.</target>

src/Analyzers/MSTest.Analyzers/xlf/Resources.es.xlf

@@ -281,6 +281,21 @@ El tipo que declara estos métodos también debe respetar las reglas siguientes:
         <target state="translated">No almacenar TestContext en un miembro estático</target>
         <note />
       </trans-unit>
+      <trans-unit id="DoNotUseShadowingDescription">
+        <source>Shadowing test members could cause testing issues (such as NRE).</source>
+        <target state="new">Shadowing test members could cause testing issues (such as NRE).</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingMessageFormat">
+        <source>Member '{0}' is already exist in the base class</source>
+        <target state="new">Member '{0}' is already exist in the base class</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingTitle">
+        <source>Do not use shadowing</source>
+        <target state="new">Do not use shadowing</target>
+        <note />
+      </trans-unit>
       <trans-unit id="DoNotUseSystemDescriptionAttributeDescription">
         <source>'System.ComponentModel.DescriptionAttribute' has no effect in the context of tests and you likely wanted to use 'Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute' instead.</source>
         <target state="translated">"System.ComponentModel.DescriptionAttribute" no tiene ningún efecto en el contexto de las pruebas y es probable que quiera usar "Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute" en su lugar.</target>

src/Analyzers/MSTest.Analyzers/xlf/Resources.fr.xlf

@@ -281,6 +281,21 @@ Le type doit être une classe
         <target state="translated">Ne pas stocker TestContext dans un membre statique</target>
         <note />
       </trans-unit>
+      <trans-unit id="DoNotUseShadowingDescription">
+        <source>Shadowing test members could cause testing issues (such as NRE).</source>
+        <target state="new">Shadowing test members could cause testing issues (such as NRE).</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingMessageFormat">
+        <source>Member '{0}' is already exist in the base class</source>
+        <target state="new">Member '{0}' is already exist in the base class</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingTitle">
+        <source>Do not use shadowing</source>
+        <target state="new">Do not use shadowing</target>
+        <note />
+      </trans-unit>
       <trans-unit id="DoNotUseSystemDescriptionAttributeDescription">
         <source>'System.ComponentModel.DescriptionAttribute' has no effect in the context of tests and you likely wanted to use 'Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute' instead.</source>
         <target state="translated">« System.ComponentModel.DescriptionAttribute » n’a aucun effet dans le contexte des tests et vous vouliez probablement utiliser « Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute » à la place.</target>

src/Analyzers/MSTest.Analyzers/xlf/Resources.it.xlf

@@ -281,6 +281,21 @@ Anche il tipo che dichiara questi metodi deve rispettare le regole seguenti:
         <target state="translated">Non archiviare TestContext in un membro statico</target>
         <note />
       </trans-unit>
+      <trans-unit id="DoNotUseShadowingDescription">
+        <source>Shadowing test members could cause testing issues (such as NRE).</source>
+        <target state="new">Shadowing test members could cause testing issues (such as NRE).</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingMessageFormat">
+        <source>Member '{0}' is already exist in the base class</source>
+        <target state="new">Member '{0}' is already exist in the base class</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingTitle">
+        <source>Do not use shadowing</source>
+        <target state="new">Do not use shadowing</target>
+        <note />
+      </trans-unit>
       <trans-unit id="DoNotUseSystemDescriptionAttributeDescription">
         <source>'System.ComponentModel.DescriptionAttribute' has no effect in the context of tests and you likely wanted to use 'Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute' instead.</source>
         <target state="translated">'System.ComponentModel.DescriptionAttribute' non ha alcun effetto in un contesto di test ed è probabile che si intendesse usare 'Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute'.</target>

src/Analyzers/MSTest.Analyzers/xlf/Resources.ja.xlf

@@ -281,6 +281,21 @@ The type declaring these methods should also respect the following rules:
         <target state="translated">静的メンバーに TestContext を格納しない</target>
         <note />
       </trans-unit>
+      <trans-unit id="DoNotUseShadowingDescription">
+        <source>Shadowing test members could cause testing issues (such as NRE).</source>
+        <target state="new">Shadowing test members could cause testing issues (such as NRE).</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingMessageFormat">
+        <source>Member '{0}' is already exist in the base class</source>
+        <target state="new">Member '{0}' is already exist in the base class</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="DoNotUseShadowingTitle">
+        <source>Do not use shadowing</source>
+        <target state="new">Do not use shadowing</target>
+        <note />
+      </trans-unit>
       <trans-unit id="DoNotUseSystemDescriptionAttributeDescription">
         <source>'System.ComponentModel.DescriptionAttribute' has no effect in the context of tests and you likely wanted to use 'Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute' instead.</source>
         <target state="translated">'System.ComponentModel.DescriptionAttribute' はテストのコンテキストでは効果がないため、代わりに 'Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute' を使用する必要がある可能性があります。</target>