Make controllers with ApiControllerAttribute visible in ApiExplorer

Author: pranavkm

src/Microsoft.AspNetCore.Mvc.Core/Internal/ApiBehaviorApplicationModelProvider.cs

@@ -57,6 +57,13 @@ public void OnProvidersExecuting(ApplicationModelProviderContext context)
             foreach (var controllerModel in context.Result.Controllers)
             {
                 var isApiController = controllerModel.Attributes.OfType<IApiBehaviorMetadata>().Any();
+                if (isApiController &&
+                    controllerModel.ApiExplorer.IsVisible == null)
+                {
+                    // Enable ApiExplorer for the controller if it wasn't already explicitly configured.
+                    controllerModel.ApiExplorer.IsVisible = true;
+                }
+
                 var controllerHasSelectorModel = controllerModel.Selectors.Any(s => s.AttributeRouteModel != null);
 
                 foreach (var actionModel in controllerModel.Actions)

test/Microsoft.AspNetCore.Mvc.Core.Test/Internal/ApiBehaviorApplicationModelProviderTest.cs

@@ -102,6 +102,47 @@ public void OnProvidersExecuting_SkipsAddingFilterToActionIfFeatureIsDisabledUsi
                 });
         }
 
+        [Fact]
+        public void OnProvidersExecuting_MakesControllerVisibleInApiExplorer_IfItIsAnnotatedWithAttribute()
+        {
+            // Arrange
+            var context = GetContext(typeof(TestApiController));
+            var options = new TestOptionsManager<ApiBehaviorOptions>(new ApiBehaviorOptions
+            {
+                SuppressModelStateInvalidFilter = true,
+            });
+
+            var provider = GetProvider(options);
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            var controller = Assert.Single(context.Result.Controllers);
+            Assert.True(controller.ApiExplorer.IsVisible);
+        }
+
+        [Fact]
+        public void OnProvidersExecuting_DoesNotModifyVisibilityInApiExplorer_IfValueIsAlreadySet()
+        {
+            // Arrange
+            var context = GetContext(typeof(TestApiController));
+            context.Result.Controllers[0].ApiExplorer.IsVisible = false;
+            var options = new TestOptionsManager<ApiBehaviorOptions>(new ApiBehaviorOptions
+            {
+                SuppressModelStateInvalidFilter = true,
+            });
+
+            var provider = GetProvider(options);
+
+            // Act
+            provider.OnProvidersExecuting(context);
+
+            // Assert
+            var controller = Assert.Single(context.Result.Controllers);
+            Assert.False(controller.ApiExplorer.IsVisible);
+        }
+
         [Fact]
         public void OnProvidersExecuting_ThrowsIfControllerWithAttribute_HasActionsWithoutAttributeRouting()
         {