Support conditional expressions in API1000/API1001 analyzers

src/Mvc/Mvc.Api.Analyzers/src/ActualApiResponseMetadataFactory.cs

@@ -59,9 +59,9 @@ void AnalyzeResponseExpression(IReturnOperation returnOperation)
     internal static ActualApiResponseMetadata?[] InspectReturnOperation(
         in ApiControllerSymbolCache symbolCache,
         IReturnOperation returnOperation,
-        ISwitchExpressionArmOperation? armOperation = null)
+        IOperation? overrideReturnedValue = null)
     {
-        var returnedValue = armOperation?.Value ?? returnOperation.ReturnedValue;
+        var returnedValue = overrideReturnedValue ?? returnOperation.ReturnedValue;
         var defaultStatusCodeAttributeSymbol = symbolCache.DefaultStatusCodeAttribute;
 
         if (returnedValue is null || returnedValue is IInvalidOperation)
@@ -106,13 +106,21 @@ void AnalyzeResponseExpression(IReturnOperation returnOperation)
             for (var i = 0; i < switchExpression.Arms.Length; i++)
             {
                 var arm = switchExpression.Arms[i];
-                var armMetadata = InspectReturnOperation(symbolCache, returnOperation, arm);
+                var armMetadata = InspectReturnOperation(symbolCache, returnOperation, arm.Value);
                 metadata.AddRange(armMetadata);
             }
 
             return metadata.ToArray();
         }
 
+        if (returnedValue is IConditionalOperation conditionalOperation)
+        {
+            var metadata = new List<ActualApiResponseMetadata?>();
+            metadata.AddRange(InspectReturnOperation(symbolCache, returnOperation, conditionalOperation.WhenTrue));
+            metadata.AddRange(InspectReturnOperation(symbolCache, returnOperation, conditionalOperation.WhenFalse));
+            return metadata.ToArray();
+        }
+
         ITypeSymbol? returnType = null;
         switch (returnedValue)
         {

src/Mvc/Mvc.Api.Analyzers/test/ActualApiResponseMetadataFactoryTest.cs

@@ -87,6 +87,64 @@ public IActionResult Get(int id)
         Assert.Null(metadata);
     }
 
+    [Fact]
+    public async Task InspectReturnExpression_RecursesIntoConditionalExpression()
+    {
+        // Arrange & Act
+        var source = @"
+using Microsoft.AspNetCore.Mvc;
+
+namespace Microsoft.AspNetCore.Mvc.Api.Analyzers
+{
+    [ApiController]
+    public class TestController : ControllerBase
+    {
+        public IActionResult Get(int id)
+        {
+            return id == 0 ? NotFound() : Ok();
+        }
+    }
+}";
+        var actualResponseMetadata = await RunInspectReturnStatementSyntax(source, "TestController");
+
+        // Assert
+        Assert.Equal(2, actualResponseMetadata.Length);
+        Assert.NotNull(actualResponseMetadata[0]);
+        Assert.Equal(404, actualResponseMetadata[0].Value.StatusCode);
+        Assert.NotNull(actualResponseMetadata[1]);
+        Assert.Equal(200, actualResponseMetadata[1].Value.StatusCode);
+    }
+
+    [Fact]
+    public async Task InspectReturnExpression_RecursesIntoNestedConditionalExpression()
+    {
+        // Arrange & Act
+        var source = @"
+using Microsoft.AspNetCore.Mvc;
+
+namespace Microsoft.AspNetCore.Mvc.Api.Analyzers
+{
+    [ApiController]
+    public class TestController : ControllerBase
+    {
+        public IActionResult Get(int id)
+        {
+            return id == 0 ? NotFound() : id == 1 ? BadRequest() : Ok();
+        }
+    }
+}";
+        var actualResponseMetadata = await RunInspectReturnStatementSyntax(source, "TestController");
+
+        // Assert
+        Assert.Equal(3, actualResponseMetadata.Length);
+        Assert.NotNull(actualResponseMetadata[0]);
+        Assert.Equal(404, actualResponseMetadata[0].Value.StatusCode);
+        Assert.NotNull(actualResponseMetadata[1]);
+        Assert.Equal(400, actualResponseMetadata[1].Value.StatusCode);
+        Assert.NotNull(actualResponseMetadata[2]);
+        Assert.Equal(200, actualResponseMetadata[2].Value.StatusCode);
+    }
+
     [Theory]
     [InlineData(ReturnOperationTestVariant.Default)]
     [InlineData(ReturnOperationTestVariant.SwitchExpression)]

src/Mvc/Mvc.Api.Analyzers/test/ApiConventionAnalyzerIntegrationTest.cs

@@ -29,8 +29,17 @@ public Task NoDiagnosticsAreReturned_ForOkResultReturningAction()
         => RunNoDiagnosticsAreReturned();
 
     [Fact]
-    public Task NoDiagnosticsAreReturned_ForApiController_IfStatusCodesCannotBeInferred()
-        => RunNoDiagnosticsAreReturned();
+    public async Task DiagnosticsAreReturned_ForApiController_IfConditionalExpressionReturnsUndocumentedStatusCodes()
+    {
+        // Arrange
+        var testSource = MvcTestSource.Read(GetType().Name, "DiagnosticsAreReturned_ForApiController_IfConditionalExpressionReturnsUndocumentedStatusCodes");
+
+        // Act
+        var result = await Executor.GetDiagnosticsAsync(testSource.Source);
+
+        // Assert
+        Assert.Contains(result, d => d.Id == ApiDiagnosticDescriptors.API1000_ActionReturnsUndocumentedStatusCode.Id);
+    }
 
     [Fact]
     public Task NoDiagnosticsAreReturned_ForReturnStatementsInLambdas()
@@ -171,6 +180,117 @@ public IActionResult Get(bool b)
         Assert.Contains(result, d => d.Id == ApiDiagnosticDescriptors.API1000_ActionReturnsUndocumentedStatusCode.Id);
     }
 
+    [Fact]
+    public async Task DiagnosticsAreReturned_ForActionsReturnedFromConditionalExpression()
+    {
+        // Arrange
+        var source = @"
+using Microsoft.AspNetCore.Mvc;
+
+namespace Test
+{
+    [ApiController]
+    public class Foo : ControllerBase
+    {
+        [ProducesResponseType(typeof(string), 200)]
+        public IActionResult Get(int id)
+        {
+            return id == 0 ? NotFound() : Ok();
+        }
+    }
+}";
+        var testSource = TestSource.Read(source);
+
+        // Act
+        var result = await Executor.GetDiagnosticsAsync(testSource.Source);
+
+        // Assert
+        Assert.Contains(result, d => d.Id == ApiDiagnosticDescriptors.API1000_ActionReturnsUndocumentedStatusCode.Id);
+    }
+
+    [Fact]
+    public async Task DiagnosticsAreReturned_ForActionsReturnedFromNestedConditionalExpression()
+    {
+        // Arrange
+        var source = @"
+using Microsoft.AspNetCore.Mvc;
+
+namespace Test
+{
+    [ApiController]
+    public class Foo : ControllerBase
+    {
+        [ProducesResponseType(typeof(string), 200)]
+        public IActionResult Get(int id)
+        {
+            return id == 0 ? NotFound() : id == 1 ? BadRequest() : Ok();
+        }
+    }
+}";
+        var testSource = TestSource.Read(source);
+
+        // Act
+        var result = await Executor.GetDiagnosticsAsync(testSource.Source);
+
+        // Assert
+        Assert.Contains(result, d => d.Id == ApiDiagnosticDescriptors.API1000_ActionReturnsUndocumentedStatusCode.Id);
+    }
+
+    [Fact]
+    public async Task NoDiagnosticsAreReturned_ForConditionalExpressionWithAllDocumentedStatusCodes()
+    {
+        // Arrange
+        var source = @"
+using Microsoft.AspNetCore.Mvc;
+
+namespace Test
+{
+    [ApiController]
+    public class Foo : ControllerBase
+    {
+        [ProducesResponseType(200)]
+        [ProducesResponseType(404)]
+        public IActionResult Get(int id)
+        {
+            return id == 0 ? NotFound() : Ok();
+        }
+    }
+}";
+        var testSource = TestSource.Read(source);
+
+        // Act
+        var result = await Executor.GetDiagnosticsAsync(testSource.Source);
+
+        // Assert
+        Assert.DoesNotContain(result, d => d.Id == ApiDiagnosticDescriptors.API1000_ActionReturnsUndocumentedStatusCode.Id);
+    }
+
+    [Fact]
+    public async Task DiagnosticsAreReturned_ForExpressionBodiedMemberWithConditionalExpression()
+    {
+        // Arrange
+        var source = @"
+using Microsoft.AspNetCore.Mvc;
+
+namespace Test
+{
+    [ApiController]
+    public class Foo : ControllerBase
+    {
+        [ProducesResponseType(typeof(string), 200)]
+        public IActionResult Get(int id)
+            => id == 0 ? NotFound() : Ok();
+    }
+}";
+        var testSource = TestSource.Read(source);
+
+        // Act
+        var result = await Executor.GetDiagnosticsAsync(testSource.Source);
+
+        // Assert
+        Assert.Contains(result, d => d.Id == ApiDiagnosticDescriptors.API1000_ActionReturnsUndocumentedStatusCode.Id);
+    }
+
         [Fact]
     public async Task DiagnosticsAreReturned_ForActionsReturnedFromSwitchStatement()
     {

src/Mvc/Mvc.Api.Analyzers/test/TestFiles/ApiConventionAnalyzerIntegrationTest/DiagnosticsAreReturned_ForApiController_IfConditionalExpressionReturnsUndocumentedStatusCodes.cs

@@ -0,0 +1,15 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+namespace Microsoft.AspNetCore.Mvc.Api.Analyzers
+{
+    [ApiController]
+    public class DiagnosticsAreReturned_ForApiController_IfConditionalExpressionReturnsUndocumentedStatusCodes : ControllerBase
+    {
+        [ProducesResponseType(201)]
+        public IActionResult Method(int id)
+        {
+            return id == 0 ? /*MM*/(IActionResult)NotFound() : Ok();
+        }
+    }
+}