Default Status Code for void types changed to 200

Fixes #4838

src/Microsoft.AspNetCore.Mvc.ApiExplorer/DefaultApiDescriptionProvider.cs

@@ -377,8 +377,7 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
 
             // Set the default status only when no status has already been set explicitly
             if (objectTypes.Count == 0
-                && type != null
-                && type != typeof(void))
+                && type != null)
             {
                 objectTypes[StatusCodes.Status200OK] = type;
             }

test/Microsoft.AspNetCore.Mvc.ApiExplorer.Test/DefaultApiDescriptionProviderTest.cs

@@ -509,7 +509,7 @@ namespace Microsoft.AspNetCore.Mvc.Description
                         new ProducesAttribute("text/json", "application/json"),
                         FilterScope.Action),
                     new FilterDescriptor(
-                        new ProducesResponseTypeAttribute(typeof(void), 204),
+                        new ProducesResponseTypeAttribute(typeof(void), 200),
                         FilterScope.Action),
                     new FilterDescriptor(
                         new ProducesResponseTypeAttribute(typeof(BadData), 400),
@@ -569,7 +569,7 @@ namespace Microsoft.AspNetCore.Mvc.Description
                 responseType =>
                 {
                     Assert.Equal(typeof(void), responseType.Type);
-                    Assert.Equal(204, responseType.StatusCode);
+                    Assert.Equal(200, responseType.StatusCode);
                     Assert.Null(responseType.ModelMetadata);
                     Assert.Empty(responseType.ApiResponseFormats);
                 },
@@ -592,7 +592,26 @@ namespace Microsoft.AspNetCore.Mvc.Description
         [Theory]
         [InlineData(nameof(ReturnsVoid))]
         [InlineData(nameof(ReturnsTask))]
-        public void GetApiDescription_DoesNotPopulatesResponseInformation_WhenVoid(string methodName)
+        public void GetApiDescription_DefaultVoidStatus(string methodName)
+        {
+            // Arrange
+            var action = CreateActionDescriptor(methodName);
+
+            // Act
+            var descriptions = GetApiDescriptions(action);
+
+            // Assert
+            var description = Assert.Single(descriptions);
+            var responseType = Assert.Single(description.SupportedResponseTypes);
+            Assert.Equal(typeof(void), responseType.Type);
+            Assert.Equal(200, responseType.StatusCode);
+            Assert.Null(responseType.ModelMetadata);
+        }
+
+        [Theory]
+        [InlineData(nameof(ReturnsVoid))]
+        [InlineData(nameof(ReturnsTask))]
+        public void GetApiDescription_VoidWithResponseTypeAttributeStatus(string methodName)
         {
             // Arrange
             var action = CreateActionDescriptor(methodName);

test/Microsoft.AspNetCore.Mvc.FunctionalTests/ApiExplorerTest.cs

@@ -393,10 +393,30 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             Assert.Single(result, d => d.HttpMethod == "POST");
         }
 
+        [Theory]
+        [InlineData("GetVoidWithExplicitResponseTypeStatusCode")]
+        [InlineData("GetTaskWithExplicitResponseTypeStatusCode")]
+        public async Task ApiExplorer_ResponseType_VoidWithResponseTypeAttributeStatusCode(string action)
+        {
+            // Arrange & Act
+            var response = await Client.GetAsync(
+                "http://localhost/ApiExplorerResponseTypeWithAttribute/" + action);
+
+            var body = await response.Content.ReadAsStringAsync();
+            var result = JsonConvert.DeserializeObject<List<ApiExplorerData>>(body);
+
+            // Assert
+            var description = Assert.Single(result);
+            var responseType = Assert.Single(description.SupportedResponseTypes);
+            Assert.Equal(typeof(void).FullName, responseType.ResponseType);
+            Assert.Equal(204, responseType.StatusCode);
+            Assert.Empty(responseType.ResponseFormats);
+        }
+
         [Theory]
         [InlineData("GetVoid")]
         [InlineData("GetTask")]
-        public async Task ApiExplorer_ResponseType_VoidWithoutAttribute(string action)
+        public async Task ApiExplorer_ResponseType_VoidWithoutAttributeDefaultStatusCode(string action)
         {
             // Arrange & Act
             var response = await Client.GetAsync(
@@ -409,7 +429,7 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
             var description = Assert.Single(result);
             var responseType = Assert.Single(description.SupportedResponseTypes);
             Assert.Equal(typeof(void).FullName, responseType.ResponseType);
-            Assert.Equal(204, responseType.StatusCode);
+            Assert.Equal(200, responseType.StatusCode);
             Assert.Empty(responseType.ResponseFormats);
         }
 

test/WebSites/ApiExplorerWebSite/Controllers/ApiExplorerResponseTypeWithAttributeController.cs

@@ -10,6 +10,12 @@ namespace ApiExplorerWebSite
     [Route("[controller]/[Action]")]
     public class ApiExplorerResponseTypeWithAttributeController : Controller
     {
+        [HttpGet]
+        [ProducesResponseType(typeof(void), 204)]
+        public void GetVoidWithExplicitResponseTypeStatusCode()
+        {
+        }
+
         [HttpGet]
         [Produces(typeof(Customer))]
         public void GetVoid()
@@ -30,6 +36,13 @@ namespace ApiExplorerWebSite
             return new EmptyResult();
         }
 
+        [HttpGet]
+        [ProducesResponseType(typeof(void), 204)]
+        public Task GetTaskWithExplicitResponseTypeStatusCode()
+        {
+            return Task.FromResult(true);
+        }
+
         [HttpGet]
         [Produces("application/json", Type = typeof(int))]
         public Task GetTask()

test/WebSites/ApiExplorerWebSite/Controllers/ApiExplorerResponseTypeWithoutAttributeController.cs

@@ -10,7 +10,6 @@ namespace ApiExplorerWebSite
     public class ApiExplorerResponseTypeWithoutAttributeController : Controller
     {
         [HttpGet]
-        [ProducesResponseType(typeof(void), 204)]
         public void GetVoid()
         {
         }
@@ -46,7 +45,6 @@ namespace ApiExplorerWebSite
         }
 
         [HttpGet]
-        [ProducesResponseType(typeof(void), 204)]
         public Task GetTask()
         {
             return Task.FromResult(true);