Fix missing response schema bug

src/Microsoft.OpenApi.Readers/V2/OpenApiOperationDeserializer.cs

@@ -67,7 +67,7 @@ internal static partial class OpenApiV2Deserializer
                 {
                     "produces", (o, n) => {
                         var produces = n.CreateSimpleList(s => s.GetScalarValue());
-                        if (produces.Count > 0) {
+                        if (produces != null) {
                             n.Context.SetTempStorage(TempStorageKeys.OperationProduces, produces);
                         }
                     }

src/Microsoft.OpenApi.Readers/V2/OpenApiResponseDeserializer.cs

@@ -74,11 +74,23 @@ private static void ProcessProduces(MapNode mapNode, OpenApiResponse response, P
 
             var produces = context.GetFromTempStorage<List<string>>(TempStorageKeys.OperationProduces)
                 ?? context.GetFromTempStorage<List<string>>(TempStorageKeys.GlobalProduces);
+
             if (produces != null)
             {
+                var schema = context.GetFromTempStorage<OpenApiSchema>(TempStorageKeys.ResponseSchema, response);
+
+                if (produces.Count == 0 && schema != null)
+                {
+                    var mediaType = new OpenApiMediaType
+                    {
+                        Schema = schema
+                    };
+
+                    response.Content.Add(string.Empty, mediaType);
+                }
+
                 foreach (var produce in produces)
                 {
-                    var schema = context.GetFromTempStorage<OpenApiSchema>(TempStorageKeys.ResponseSchema, response);
 
                     if (response.Content.ContainsKey(produce) && response.Content[produce] != null)
                     {

test/Microsoft.OpenApi.Readers.Tests/Microsoft.OpenApi.Readers.Tests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
     <PropertyGroup>
         <TargetFrameworks>net7.0</TargetFrameworks>
         <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
@@ -55,6 +55,7 @@
             <CopyToOutputDirectory>Never</CopyToOutputDirectory>
         </EmbeddedResource>
         <EmbeddedResource Include="V2Tests\Samples\OpenApiOperation\operationWithResponseExamples.yaml" />
+        <EmbeddedResource Include="V2Tests\Samples\OpenApiOperation\operationWithEmptyProducesArrayInResponse.json" />
       <EmbeddedResource Include="V2Tests\Samples\OpenApiParameter\bodyParameter.yaml">
         <CopyToOutputDirectory>Never</CopyToOutputDirectory>
       </EmbeddedResource>

test/Microsoft.OpenApi.Readers.Tests/V2Tests/OpenApiOperationTests.cs

@@ -375,5 +375,49 @@ public void ParseOperationWithResponseExamplesShouldSucceed()
                 }
             );
         }
+
+        [Fact]
+        public void ParseOperationWithEmptyProducesArraySetsResponseSchemaIfExists()
+        {
+            // Arrange
+            MapNode node;
+            using (var stream = Resources.GetStream(Path.Combine(SampleFolderPath, "operationWithEmptyProducesArrayInResponse.json")))
+            {
+                node = TestHelper.CreateYamlMapNode(stream);
+            }
+
+            // Act
+            var operation = OpenApiV2Deserializer.LoadOperation(node);
+
+            // Assert
+            operation.Should().BeEquivalentTo(
+                new OpenApiOperation()
+                {
+                    Responses = new OpenApiResponses()
+                    {
+                        { "200", new OpenApiResponse()
+                        {
+                            Description = "OK",
+                            Content =
+                            {
+                                [""] = new OpenApiMediaType()
+                                {
+                                    Schema = new OpenApiSchema()
+                                    {
+                                        Format = "binary",
+                                        Description = "The content of the file.",
+                                        Type = "string",
+                                        Extensions =
+                                        {
+                                            ["x-ms-summary"] = new OpenApiString("File Content")
+                                        }
+                                    }
+                                }
+                            }
+                        }}
+                    }
+                }
+            );
+        }
     }
 }

test/Microsoft.OpenApi.Readers.Tests/V2Tests/Samples/OpenApiOperation/operationWithEmptyProducesArrayInResponse.json

@@ -0,0 +1,14 @@
+{
+    "produces": [],
+    "responses": {
+        "200": {
+            "description": "OK",
+            "schema": {
+                "format": "binary",
+                "description": "The content of the file.",
+                "type": "string",
+                "x-ms-summary": "File Content"
+            }
+        }
+    }
+}