Fix ambiguous route analyzer false positive with switch (#51881) (#52035)

Author: JamesNK

src/Framework/AspNetCoreAnalyzers/src/Analyzers/RouteHandlers/DetectAmbiguousRoutes.cs

@@ -31,11 +31,11 @@ private static void DetectAmbiguousRoutes(in OperationBlockAnalysisContext conte
             .Where(u => u.ResolvedOperation != null && !u.MapOperation.RouteUsageModel.UsageContext.HttpMethods.IsDefault)
             .GroupBy(u => new MapOperationGroupKey(u.MapOperation.Builder, u.ResolvedOperation!, u.MapOperation.RouteUsageModel.RoutePattern, u.MapOperation.RouteUsageModel.UsageContext.HttpMethods));
 
-        foreach (var ambigiousGroup in groupedByParent.Where(g => g.Count() >= 2))
+        foreach (var ambiguousGroup in groupedByParent.Where(g => g.Count() >= 2))
         {
-            foreach (var ambigiousMapOperation in ambigiousGroup)
+            foreach (var ambiguousMapOperation in ambiguousGroup)
             {
-                var model = ambigiousMapOperation.MapOperation.RouteUsageModel;
+                var model = ambiguousMapOperation.MapOperation.RouteUsageModel;
 
                 context.ReportDiagnostic(Diagnostic.Create(
                     DiagnosticDescriptors.AmbiguousRouteHandlerRoute,
@@ -67,15 +67,16 @@ private static void DetectAmbiguousRoutes(in OperationBlockAnalysisContext conte
 
         while (current != null)
         {
-            if (current.Parent is IBlockOperation blockOperation)
+            if (current.Parent is IBlockOperation or ISwitchCaseOperation)
             {
-                return blockOperation;
+                return current.Parent;
             }
             else if (current.Parent is IConditionalOperation or
                 ICoalesceOperation or
                 IAssignmentOperation or
                 IArgumentOperation or
-                IInvocationOperation)
+                IInvocationOperation or
+                ISwitchExpressionArmOperation)
             {
                 return current;
             }

src/Framework/AspNetCoreAnalyzers/test/RouteHandlers/DetectAmbiguousMappedRoutesTest.cs

@@ -97,6 +97,79 @@ void Hello() { }
         await VerifyCS.VerifyAnalyzerAsync(source);
     }
 
+    [Fact]
+    public async Task DuplicateRoutes_SwitchStatement_NoDiagnostics()
+    {
+        // Arrange
+        var source = @"
+using System;
+using Microsoft.AspNetCore.Builder;
+var app = WebApplication.Create();
+switch (Random.Shared.Next())
+{
+    case 0:
+        app.MapGet(""/"", () => Hello());
+        return;
+    case 1:
+        app.MapGet(""/"", () => Hello());
+        return;
+}
+void Hello() { }
+";
+
+        // Act & Assert
+        await VerifyCS.VerifyAnalyzerAsync(source);
+    }
+
+    [Fact]
+    public async Task DuplicateRoutes_InsideSwitchStatement_HasDiagnostics()
+    {
+        // Arrange
+        var source = @"
+using System;
+using Microsoft.AspNetCore.Builder;
+var app = WebApplication.Create();
+switch (Random.Shared.Next())
+{
+    case 0:
+        app.MapGet({|#0:""/""|}, () => Hello());
+        app.MapGet({|#1:""/""|}, () => Hello());
+        return;
+
+}
+void Hello() { }
+";
+
+        var expectedDiagnostics = new[] {
+            new DiagnosticResult(DiagnosticDescriptors.AmbiguousRouteHandlerRoute).WithArguments("/").WithLocation(0),
+            new DiagnosticResult(DiagnosticDescriptors.AmbiguousRouteHandlerRoute).WithArguments("/").WithLocation(1)
+        };
+
+        // Act & Assert
+        await VerifyCS.VerifyAnalyzerAsync(source, expectedDiagnostics);
+    }
+
+    [Fact]
+    public async Task DuplicateRoutes_SwitchExpression_NoDiagnostics()
+    {
+        // Arrange
+        var source = @"
+using System;
+using Microsoft.AspNetCore.Builder;
+var app = WebApplication.Create();
+_ = Random.Shared.Next() switch
+{
+    0 => app.MapGet(""/"", () => Hello()),
+    1 => app.MapGet(""/"", () => Hello()),
+    _ => throw new Exception()
+};
+void Hello() { }
+";
+
+        // Act & Assert
+        await VerifyCS.VerifyAnalyzerAsync(source);
+    }
+
     [Fact]
     public async Task DuplicateRoutes_NullCoalescing_NoDiagnostics()
     {
@@ -166,6 +239,30 @@ void Hello() { }
         await VerifyCS.VerifyAnalyzerAsync(source);
     }
 
+    [Fact]
+    public async Task DuplicateMapGetRoutes_DuplicatesInsideConditional_NoDiagnostics()
+    {
+        // Arrange
+        var source = @"
+using Microsoft.AspNetCore.Builder;
+var app = WebApplication.Create();
+if (true)
+{
+    app.MapGet({|#0:""/""|}, () => Hello());
+    app.MapGet({|#1:""/""|}, () => Hello());
+}
+void Hello() { }
+";
+
+        var expectedDiagnostics = new[] {
+            new DiagnosticResult(DiagnosticDescriptors.AmbiguousRouteHandlerRoute).WithArguments("/").WithLocation(0),
+            new DiagnosticResult(DiagnosticDescriptors.AmbiguousRouteHandlerRoute).WithArguments("/").WithLocation(1)
+        };
+
+        // Act & Assert
+        await VerifyCS.VerifyAnalyzerAsync(source, expectedDiagnostics);
+    }
+
     [Fact]
     public async Task DuplicateRoutes_UnknownUsageOfEndConventionBuilderExtension_NoDiagnostics()
     {