Fix binary operation result type generation for AspNetCore CSharp

src/NSwag.CodeGeneration.CSharp.Tests/BinaryTests.cs

@@ -500,5 +500,51 @@ public async Task When_multipart_inline_schema()
             await VerifyHelper.Verify(code);
             CSharpCompiler.AssertCompile(code);
         }
+
+        [Fact]
+        public async Task When_response_body_is_binary_then_IActionResult_is_used_as_return_type_in_CSharp_ASPNETCore()
+        {
+          var yaml = @"openapi: 3.0.0
+servers:
+  - url: https://www.example.com/
+info:
+  version: '2.0.0'
+  title: 'Test API'   
+paths:
+  /logo:
+    get:
+      tags:
+        - Files
+      summary: 'Get logo'
+      operationId: getLogo
+      responses:
+        '200':
+          description: 'something'
+          content:
+            image/png:
+              schema:
+                type: string
+                format: binary";
+
+          var document = await OpenApiYamlDocument.FromYamlAsync(yaml);
+
+          // Act
+          CSharpControllerGeneratorSettings settings = new CSharpControllerGeneratorSettings
+          {
+            ControllerTarget = CSharpControllerTarget.AspNetCore,
+            ControllerStyle = CSharpControllerStyle.Abstract,
+            UseActionResultType = true,
+
+          };
+
+          var codeGenerator = new CSharpControllerGenerator(document, settings);
+          var code = codeGenerator.GenerateFile();
+
+          // Assert
+          await VerifyHelper.Verify(code);
+          CSharpCompiler.AssertCompile(code);
+          Assert.DoesNotContain("ActionResult<Microsoft.AspNetCore.Mvc.FileResult>", code);
+          Assert.Contains("System.Threading.Tasks.Task<Microsoft.AspNetCore.Mvc.IActionResult> GetLogo", code);
+        }
     }
 }

src/NSwag.CodeGeneration.CSharp.Tests/Snapshots/BinaryTests.When_response_body_is_binary_then_IActionResult_is_used_as_return_type_in_CSharp_ASPNETCore.verified.txt

@@ -0,0 +1,54 @@
+
+
+namespace MyNamespace
+{
+    using System = global::System;
+
+
+    public abstract class ControllerBase : Microsoft.AspNetCore.Mvc.ControllerBase
+    {
+        [Microsoft.AspNetCore.Mvc.HttpGet, Microsoft.AspNetCore.Mvc.Route("logo")]
+        public abstract System.Threading.Tasks.Task<Microsoft.AspNetCore.Mvc.IActionResult> GetLogo();
+
+    }
+
+
+
+    public partial class FileResponse : System.IDisposable
+    {
+        private System.IDisposable _client;
+        private System.IDisposable _response;
+
+        public int StatusCode { get; private set; }
+
+        public System.Collections.Generic.IReadOnlyDictionary<string, System.Collections.Generic.IEnumerable<string>> Headers { get; private set; }
+
+        public System.IO.Stream Stream { get; private set; }
+
+        public bool IsPartial
+        {
+            get { return StatusCode == 206; }
+        }
+
+        public FileResponse(int statusCode, System.Collections.Generic.IReadOnlyDictionary<string, System.Collections.Generic.IEnumerable<string>> headers, System.IO.Stream stream, System.IDisposable client, System.IDisposable response)
+        {
+            StatusCode = statusCode;
+            Headers = headers;
+            Stream = stream;
+            _client = client;
+            _response = response;
+        }
+
+        public void Dispose()
+        {
+            Stream.Dispose();
+            if (_response != null)
+                _response.Dispose();
+            if (_client != null)
+                _client.Dispose();
+        }
+    }
+
+
+
+}

src/NSwag.CodeGeneration.CSharp/Models/CSharpControllerOperationModel.cs

@@ -38,6 +38,7 @@ public override string ResultType
                     {
                         case "void":
                         case "FileResult":
+                        case "Microsoft.AspNetCore.Mvc.FileResult":
                             return "System.Threading.Tasks.Task<Microsoft.AspNetCore.Mvc.IActionResult>";
                         default:
                             return "System.Threading.Tasks.Task<Microsoft.AspNetCore.Mvc.ActionResult<" + SyncResultType + ">>";