MSTEST0032: Always pass assertions

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

@@ -9,3 +9,4 @@ MSTEST0026 | Usage | Info | AssertionArgsShouldAvoidConditionalAccessRuleId, [Do
 MSTEST0029 | Design | Disabled | PublicMethodShouldBeTestMethodAnalyzer, [Documentation](https://learn.microsoft.com/dotnet/core/testing/mstest-analyzers/mstest0029)
 MSTEST0030 | Usage | Info | TypeContainingTestMethodShouldBeATestClassAnalyzer, [Documentation](https://learn.microsoft.com/dotnet/core/testing/mstest-analyzers/mstest0030)
 MSTEST0031 | Usage | Info | DoNotUseSystemDescriptionAttributeAnalyzer, [Documentation](https://learn.microsoft.com/dotnet/core/testing/mstest-analyzers/mstest0031)
+MSTEST0032 | Usage | Info | ReviewAlwaysTrueAssertConditionAnalyzer, [Documentation](https://learn.microsoft.com/dotnet/core/testing/mstest-analyzers/mstest0032)

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

@@ -35,4 +35,5 @@ internal static class DiagnosticIds
     public const string PublicMethodShouldBeTestMethodRuleId = "MSTEST0029";
     public const string TypeContainingTestMethodShouldBeATestClassRuleId = "MSTEST0030";
     public const string DoNotUseSystemDescriptionAttributeRuleId = "MSTEST0031";
+    public const string ReviewAlwaysTrueAssertConditionAnalyzerRuleId = "MSTEST0032";
 }

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

@@ -31,6 +31,8 @@ MSTest.Analyzers.PreferConstructorOverTestInitializeAnalyzer
 MSTest.Analyzers.PreferConstructorOverTestInitializeAnalyzer.PreferConstructorOverTestInitializeAnalyzer() -> void
 MSTest.Analyzers.PreferDisposeOverTestCleanupAnalyzer
 MSTest.Analyzers.PreferDisposeOverTestCleanupAnalyzer.PreferDisposeOverTestCleanupAnalyzer() -> void
+MSTest.Analyzers.ReviewAlwaysTrueAssertConditionAnalyzer
+MSTest.Analyzers.ReviewAlwaysTrueAssertConditionAnalyzer.ReviewAlwaysTrueAssertConditionAnalyzer() -> void
 MSTest.Analyzers.PreferTestCleanupOverDisposeAnalyzer
 MSTest.Analyzers.PreferTestCleanupOverDisposeAnalyzer.PreferTestCleanupOverDisposeAnalyzer() -> void
 MSTest.Analyzers.PreferTestInitializeOverConstructorAnalyzer
@@ -91,6 +93,8 @@ override MSTest.Analyzers.PreferConstructorOverTestInitializeAnalyzer.Initialize
 override MSTest.Analyzers.PreferConstructorOverTestInitializeAnalyzer.SupportedDiagnostics.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.DiagnosticDescriptor!>
 override MSTest.Analyzers.PreferDisposeOverTestCleanupAnalyzer.Initialize(Microsoft.CodeAnalysis.Diagnostics.AnalysisContext! context) -> void
 override MSTest.Analyzers.PreferDisposeOverTestCleanupAnalyzer.SupportedDiagnostics.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.DiagnosticDescriptor!>
+override MSTest.Analyzers.ReviewAlwaysTrueAssertConditionAnalyzer.Initialize(Microsoft.CodeAnalysis.Diagnostics.AnalysisContext! context) -> void
+override MSTest.Analyzers.ReviewAlwaysTrueAssertConditionAnalyzer.SupportedDiagnostics.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.DiagnosticDescriptor!>
 override MSTest.Analyzers.PreferTestCleanupOverDisposeAnalyzer.Initialize(Microsoft.CodeAnalysis.Diagnostics.AnalysisContext! context) -> void
 override MSTest.Analyzers.PreferTestCleanupOverDisposeAnalyzer.SupportedDiagnostics.get -> System.Collections.Immutable.ImmutableArray<Microsoft.CodeAnalysis.DiagnosticDescriptor!>
 override MSTest.Analyzers.PreferTestInitializeOverConstructorAnalyzer.Initialize(Microsoft.CodeAnalysis.Diagnostics.AnalysisContext! context) -> void

src/Analyzers/MSTest.Analyzers/Resources.resx

@@ -454,4 +454,10 @@
   <data name="DoNotUseSystemDescriptionAttributeDescription" xml:space="preserve">
     <value>'System.ComponentModel.DescriptionAttribute' has no effect in the context of tests and you likely wanted to use 'Microsoft.VisualStudio.TestTools.UnitTesting.DescriptionAttribute' instead.</value>
   </data>
+  <data name="ReviewAlwaysTrueAssertConditionAnalyzerTitle" xml:space="preserve">
+    <value>Assertion condition is always true</value>
+  </data>
+  <data name="ReviewAlwaysTrueAssertConditionAnalyzerMessageFormat" xml:space="preserve">
+    <value>Review or remove the assertion as its condition is known to be always true</value>
+  </data>
 </root>

src/Analyzers/MSTest.Analyzers/ReviewAlwaysTrueAssertConditionAnalyzer.cs

@@ -0,0 +1,120 @@
+// 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 Microsoft.CodeAnalysis.Operations;
+
+using MSTest.Analyzers.Helpers;
+using MSTest.Analyzers.RoslynAnalyzerHelpers;
+
+namespace MSTest.Analyzers;
+
+/// <summary>
+/// MSTEST0032: <inheritdoc cref="Resources.ReviewAlwaysTrueAssertConditionAnalyzerTitle"/>.
+/// </summary>
+[DiagnosticAnalyzer(LanguageNames.CSharp, LanguageNames.VisualBasic)]
+public sealed class ReviewAlwaysTrueAssertConditionAnalyzer : DiagnosticAnalyzer
+{
+    private enum EqualityStatus
+    {
+        Unknown,
+        Equal,
+        NotEqual,
+    }
+
+    private const string ExpectedParameterName = "expected";
+    private const string NotExpectedParameterName = "notExpected";
+    private const string ActualParameterName = "actual";
+    private const string ConditionParameterName = "condition";
+    private const string ValueParameterName = "value";
+
+    private static readonly LocalizableResourceString Title = new(nameof(Resources.ReviewAlwaysTrueAssertConditionAnalyzerTitle), Resources.ResourceManager, typeof(Resources));
+    private static readonly LocalizableResourceString MessageFormat = new(nameof(Resources.ReviewAlwaysTrueAssertConditionAnalyzerMessageFormat), Resources.ResourceManager, typeof(Resources));
+
+    internal static readonly DiagnosticDescriptor Rule = DiagnosticDescriptorHelper.Create(
+        DiagnosticIds.ReviewAlwaysTrueAssertConditionAnalyzerRuleId,
+        Title,
+        MessageFormat,
+        null,
+        Category.Design,
+        DiagnosticSeverity.Info,
+        isEnabledByDefault: true);
+
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics { get; }
+        = ImmutableArray.Create(Rule);
+
+    public override void Initialize(AnalysisContext context)
+    {
+        context.EnableConcurrentExecution();
+        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.Analyze | GeneratedCodeAnalysisFlags.ReportDiagnostics);
+
+        context.RegisterCompilationStartAction(context =>
+        {
+            Compilation compilation = context.Compilation;
+            INamedTypeSymbol? assertSymbol = compilation.GetOrCreateTypeByMetadataName(WellKnownTypeNames.MicrosoftVisualStudioTestToolsUnitTestingAssert);
+            INamedTypeSymbol? nullableSymbol = compilation.GetOrCreateTypeByMetadataName(WellKnownTypeNames.SystemNullable);
+            if (assertSymbol is not null)
+            {
+                context.RegisterOperationAction(context => AnalyzeOperation(context, assertSymbol, nullableSymbol), OperationKind.Invocation);
+            }
+        });
+    }
+
+    private static void AnalyzeOperation(OperationAnalysisContext context, INamedTypeSymbol assertSymbol, INamedTypeSymbol? nullableSymbol)
+    {
+        var operation = (IInvocationOperation)context.Operation;
+        if (assertSymbol.Equals(operation.TargetMethod.ContainingType, SymbolEqualityComparer.Default) &&
+            IsAlwaysTrue(operation, nullableSymbol))
+        {
+            context.ReportDiagnostic(operation.CreateDiagnostic(Rule));
+        }
+    }
+
+    private static bool IsAlwaysTrue(IInvocationOperation operation, INamedTypeSymbol? nullableSymbol)
+        => operation.TargetMethod.Name switch
+        {
+            "IsTrue" => GetConditionArgument(operation) is { Value.ConstantValue: { HasValue: true, Value: true } },
+            "IsFalse" => GetConditionArgument(operation) is { Value.ConstantValue: { HasValue: true, Value: false } },
+            "AreEqual" => GetEqualityStatus(operation, ExpectedParameterName) == EqualityStatus.Equal,
+            "AreNotEqual" => GetEqualityStatus(operation, NotExpectedParameterName) == EqualityStatus.NotEqual,
+            "IsNull" => GetValueArgument(operation) is { Value.ConstantValue: { HasValue: true, Value: null } },
+            "IsNotNull" => GetValueArgument(operation) is { } valueArgumentOperation && IsNotNullableType(valueArgumentOperation, nullableSymbol),
+            _ => false,
+        };
+
+    private static bool IsNotNullableType(IArgumentOperation valueArgumentOperation, INamedTypeSymbol? nullableSymbol)
+    {
+        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)
+        => operation.Arguments.FirstOrDefault(arg => arg.Parameter?.Name == name);
+
+    private static IArgumentOperation? GetConditionArgument(IInvocationOperation operation)
+        => GetArgumentWithName(operation, ConditionParameterName);
+
+    private static IArgumentOperation? GetValueArgument(IInvocationOperation operation)
+        => GetArgumentWithName(operation, ValueParameterName);
+
+    private static EqualityStatus GetEqualityStatus(IInvocationOperation operation, string expectedOrNotExpectedParameterName)
+    {
+        if (GetArgumentWithName(operation, expectedOrNotExpectedParameterName) is { } expectedOrNotExpectedArgument &&
+            GetArgumentWithName(operation, ActualParameterName) is { } actualArgument &&
+            expectedOrNotExpectedArgument.Value.ConstantValue.HasValue &&
+            actualArgument.Value.ConstantValue.HasValue)
+        {
+            return Equals(expectedOrNotExpectedArgument.Value.ConstantValue.Value, actualArgument.Value.ConstantValue.Value) ? EqualityStatus.Equal : EqualityStatus.NotEqual;
+        }
+
+        // We are not sure about the equality status
+        return EqualityStatus.Unknown;
+    }
+}

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

@@ -236,6 +236,16 @@
         <target state="translated">Místo trvalého neúspěšného vyhodnocovacího výrazu použijte „Assert.Fail“.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerMessageFormat">
+        <source>Review or remove the assertion as its condition is known to be always true</source>
+        <target state="new">Review or remove the assertion as its condition is known to be always true</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerTitle">
+        <source>Assertion condition is always true</source>
+        <target state="new">Assertion condition is always true</target>
+        <note />
+      </trans-unit>
       <trans-unit id="PreferConstructorOverTestInitializeMessageFormat">
         <source>Prefer constructors over TestInitialize methods</source>
         <target state="translated">Upřednostňovat konstruktory před metodami TestInitialize</target>

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

@@ -234,6 +234,16 @@
         <target state="translated">Verwenden Sie „Assert.Fail“ anstelle einer Assert-Anweisung, bei der immer ein Fehler auftritt.</target>
         <note />
       </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerMessageFormat">
+        <source>Review or remove the assertion as its condition is known to be always true</source>
+        <target state="new">Review or remove the assertion as its condition is known to be always true</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerTitle">
+        <source>Assertion condition is always true</source>
+        <target state="new">Assertion condition is always true</target>
+        <note />
+      </trans-unit>
       <trans-unit id="PreferConstructorOverTestInitializeMessageFormat">
         <source>Prefer constructors over TestInitialize methods</source>
         <target state="translated">Konstruktoren gegenüber TestInitialize-Methoden bevorzugen</target>

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

@@ -234,6 +234,16 @@
         <target state="translated">Usar "Assert.Fail" en lugar de una aserción que siempre tiene errores</target>
         <note />
       </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerMessageFormat">
+        <source>Review or remove the assertion as its condition is known to be always true</source>
+        <target state="new">Review or remove the assertion as its condition is known to be always true</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerTitle">
+        <source>Assertion condition is always true</source>
+        <target state="new">Assertion condition is always true</target>
+        <note />
+      </trans-unit>
       <trans-unit id="PreferConstructorOverTestInitializeMessageFormat">
         <source>Prefer constructors over TestInitialize methods</source>
         <target state="translated">Preferir constructores en lugar de métodos TestInitialize</target>

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

@@ -234,6 +234,16 @@
         <target state="translated">Utilisez « Assert.Fail » à la place d’une assertion toujours en échec</target>
         <note />
       </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerMessageFormat">
+        <source>Review or remove the assertion as its condition is known to be always true</source>
+        <target state="new">Review or remove the assertion as its condition is known to be always true</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerTitle">
+        <source>Assertion condition is always true</source>
+        <target state="new">Assertion condition is always true</target>
+        <note />
+      </trans-unit>
       <trans-unit id="PreferConstructorOverTestInitializeMessageFormat">
         <source>Prefer constructors over TestInitialize methods</source>
         <target state="translated">Préférer les constructeurs aux méthodes TestInitialize</target>

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

@@ -234,6 +234,16 @@
         <target state="translated">Usare 'Assert.Fail' invece di un'asserzione che ha sempre esito negativo</target>
         <note />
       </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerMessageFormat">
+        <source>Review or remove the assertion as its condition is known to be always true</source>
+        <target state="new">Review or remove the assertion as its condition is known to be always true</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerTitle">
+        <source>Assertion condition is always true</source>
+        <target state="new">Assertion condition is always true</target>
+        <note />
+      </trans-unit>
       <trans-unit id="PreferConstructorOverTestInitializeMessageFormat">
         <source>Prefer constructors over TestInitialize methods</source>
         <target state="translated">Preferisci costruttori rispetto ai metodi TestInitialize</target>

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

@@ -234,6 +234,16 @@
         <target state="translated">常に失敗しているアサートの代わりに 'Assert.Fail' を使用する</target>
         <note />
       </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerMessageFormat">
+        <source>Review or remove the assertion as its condition is known to be always true</source>
+        <target state="new">Review or remove the assertion as its condition is known to be always true</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerTitle">
+        <source>Assertion condition is always true</source>
+        <target state="new">Assertion condition is always true</target>
+        <note />
+      </trans-unit>
       <trans-unit id="PreferConstructorOverTestInitializeMessageFormat">
         <source>Prefer constructors over TestInitialize methods</source>
         <target state="translated">TestInitialize メソッドよりもコンストラクターを優先する</target>

src/Analyzers/MSTest.Analyzers/xlf/Resources.ko.xlf

@@ -234,6 +234,16 @@
         <target state="translated">항상 실패하는 어설션 대신 'Assert.Fail' 사용</target>
         <note />
       </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerMessageFormat">
+        <source>Review or remove the assertion as its condition is known to be always true</source>
+        <target state="new">Review or remove the assertion as its condition is known to be always true</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerTitle">
+        <source>Assertion condition is always true</source>
+        <target state="new">Assertion condition is always true</target>
+        <note />
+      </trans-unit>
       <trans-unit id="PreferConstructorOverTestInitializeMessageFormat">
         <source>Prefer constructors over TestInitialize methods</source>
         <target state="translated">TestInitialize 메서드보다 생성자 선호</target>

src/Analyzers/MSTest.Analyzers/xlf/Resources.pl.xlf

@@ -234,6 +234,16 @@
         <target state="translated">Użyj trybu „Assert.Fail” zamiast kończącej się zawsze niepowodzeniem instrukcji asercji</target>
         <note />
       </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerMessageFormat">
+        <source>Review or remove the assertion as its condition is known to be always true</source>
+        <target state="new">Review or remove the assertion as its condition is known to be always true</target>
+        <note />
+      </trans-unit>
+      <trans-unit id="ReviewAlwaysTrueAssertConditionAnalyzerTitle">
+        <source>Assertion condition is always true</source>
+        <target state="new">Assertion condition is always true</target>
+        <note />
+      </trans-unit>
       <trans-unit id="PreferConstructorOverTestInitializeMessageFormat">
         <source>Prefer constructors over TestInitialize methods</source>
         <target state="translated">Preferowanie konstruktorów niż metod TestInitialize</target>