Repro issue

Change the integration test to use HTTP client so that the middleware to write the OpenAPI document is invoked, which is where the bug is.

Going through `OpenApiDocument.SerializeAsJsonAsync()` uses a different code path that already uses a culture-invariant `TextWriter` so wasn't susceptible to the bug.

Author: martincostello

src/OpenApi/src/Extensions/OpenApiEndpointRouteBuilderExtensions.cs

@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Diagnostics.CodeAnalysis;
-using System.Globalization;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.OpenApi;
@@ -55,7 +54,7 @@ public static IEndpointConventionBuilder MapOpenApi(this IEndpointRouteBuilder e
                     var document = await documentService.GetOpenApiDocumentAsync(context.RequestServices, context.Request, context.RequestAborted);
                     var documentOptions = options.Get(lowercasedDocumentName);
 
-                    using var textWriter = new Utf8BufferTextWriter(CultureInfo.InvariantCulture);
+                    using var textWriter = new Utf8BufferTextWriter(System.Globalization.CultureInfo.InvariantCulture);
                     textWriter.SetWriter(context.Response.BodyWriter);
 
                     string contentType;

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Integration/OpenApiDocumentIntegrationTests.cs

@@ -2,10 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using Microsoft.AspNetCore.InternalTesting;
-using Microsoft.AspNetCore.OpenApi;
-using Microsoft.Extensions.DependencyInjection;
 using Microsoft.OpenApi;
-using Microsoft.OpenApi.Extensions;
 
 [UsesVerify]
 public sealed class OpenApiDocumentIntegrationTests(SampleAppFixture fixture) : IClassFixture<SampleAppFixture>
@@ -38,10 +35,8 @@ public static TheoryData<string, OpenApiSpecVersion> OpenApiDocuments()
     [MemberData(nameof(OpenApiDocuments))]
     public async Task VerifyOpenApiDocument(string documentName, OpenApiSpecVersion version)
     {
-        var documentService = fixture.Services.GetRequiredKeyedService<OpenApiDocumentService>(documentName);
-        var scopedServiceProvider = fixture.Services.CreateScope();
-        var document = await documentService.GetOpenApiDocumentAsync(scopedServiceProvider.ServiceProvider);
-        var json = await document.SerializeAsJsonAsync(version);
+        using var client = fixture.CreateClient();
+        var json = await client.GetStringAsync($"/openapi/{documentName}.json");
         var baseSnapshotsDirectory = SkipOnHelixAttribute.OnHelix()
             ? Path.Combine(Environment.GetEnvironmentVariable("HELIX_WORKITEM_ROOT"), "Integration", "snapshots")
             : "snapshots";

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Integration/snapshots/OpenApi3_0/OpenApiDocumentIntegrationTests.VerifyOpenApiDocument_documentName=controllers.verified.txt

@@ -1,9 +1,14 @@
 {
-  "openapi": "3.0.4",
+  "openapi": "3.1.1",
   "info": {
     "title": "Sample | controllers",
     "version": "1.0.0"
   },
+  "servers": [
+    {
+      "url": "http://localhost/"
+    }
+  ],
   "paths": {
     "/getbyidandname/{id}/{name}": {
       "get": {

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Integration/snapshots/OpenApi3_0/OpenApiDocumentIntegrationTests.VerifyOpenApiDocument_documentName=forms.verified.txt

@@ -1,9 +1,14 @@
 {
-  "openapi": "3.0.4",
+  "openapi": "3.1.1",
   "info": {
     "title": "Sample | forms",
     "version": "1.0.0"
   },
+  "servers": [
+    {
+      "url": "http://localhost/"
+    }
+  ],
   "paths": {
     "/forms/form-file": {
       "post": {

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Integration/snapshots/OpenApi3_0/OpenApiDocumentIntegrationTests.VerifyOpenApiDocument_documentName=responses.verified.txt

@@ -1,9 +1,14 @@
 {
-  "openapi": "3.0.4",
+  "openapi": "3.1.1",
   "info": {
     "title": "Sample | responses",
     "version": "1.0.0"
   },
+  "servers": [
+    {
+      "url": "http://localhost/"
+    }
+  ],
   "paths": {
     "/responses/200-add-xml": {
       "get": {

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Integration/snapshots/OpenApi3_0/OpenApiDocumentIntegrationTests.VerifyOpenApiDocument_documentName=schemas-by-ref.verified.txt

@@ -1,9 +1,14 @@
 {
-  "openapi": "3.0.4",
+  "openapi": "3.1.1",
   "info": {
     "title": "Sample | schemas-by-ref",
     "version": "1.0.0"
   },
+  "servers": [
+    {
+      "url": "http://localhost/"
+    }
+  ],
   "paths": {
     "/schemas-by-ref/typed-results": {
       "get": {

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Integration/snapshots/OpenApi3_0/OpenApiDocumentIntegrationTests.VerifyOpenApiDocument_documentName=v1.verified.txt

@@ -1,9 +1,14 @@
 {
-  "openapi": "3.0.4",
+  "openapi": "3.1.1",
   "info": {
     "title": "Sample | v1",
     "version": "1.0.0"
   },
+  "servers": [
+    {
+      "url": "http://localhost/"
+    }
+  ],
   "paths": {
     "/v1/array-of-guids": {
       "get": {

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Integration/snapshots/OpenApi3_0/OpenApiDocumentIntegrationTests.VerifyOpenApiDocument_documentName=v2.verified.txt

@@ -1,5 +1,5 @@
 {
-  "openapi": "3.0.4",
+  "openapi": "3.1.1",
   "info": {
     "title": "Sample | v2",
     "contact": {
@@ -11,6 +11,11 @@
     },
     "version": "1.0.0"
   },
+  "servers": [
+    {
+      "url": "http://localhost/"
+    }
+  ],
   "paths": {
     "/v2/users": {
       "get": {

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Integration/snapshots/OpenApi3_0/OpenApiDocumentIntegrationTests.VerifyOpenApiDocument_documentName=xml.verified.txt

@@ -1,9 +1,14 @@
 {
-  "openapi": "3.0.4",
+  "openapi": "3.1.1",
   "info": {
     "title": "Sample | xml",
     "version": "1.0.0"
   },
+  "servers": [
+    {
+      "url": "http://localhost/"
+    }
+  ],
   "paths": {
     "/xml/type-with-examples": {
       "get": {

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Integration/snapshots/OpenApi3_1/OpenApiDocumentIntegrationTests.VerifyOpenApiDocument_documentName=controllers.verified.txt

@@ -4,6 +4,11 @@
     "title": "Sample | controllers",
     "version": "1.0.0"
   },
+  "servers": [
+    {
+      "url": "http://localhost/"
+    }
+  ],
   "paths": {
     "/getbyidandname/{id}/{name}": {
       "get": {