More thorough support for retrieving OpenAPI routes in a case-sensitive manner

src/OpenApi/src/Extensions/OpenApiEndpointRouteBuilderExtensions.cs

@@ -50,7 +50,7 @@ public static IEndpointConventionBuilder MapOpenApi(this IEndpointRouteBuilder e
                 else
                 {
                     var document = await documentService.GetOpenApiDocumentAsync(context.RequestServices, context.RequestAborted);
-                    var documentOptions = options.Get(documentName);
+                    var documentOptions = options.Get(lowercasedDocumentName);
                     using var output = MemoryBufferWriter.Get();
                     using var writer = Utf8BufferTextWriter.Get(output);
                     try

src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Extensions/OpenApiEndpointRouteBuilderExtensionsTests.cs

@@ -12,6 +12,7 @@
 using Microsoft.OpenApi.Models;
 using Microsoft.OpenApi.Readers;
 using System.Text;
+using Microsoft.OpenApi;
 
 public class OpenApiEndpointRouteBuilderExtensionsTests : OpenApiDocumentServiceTestBase
 {
@@ -156,6 +157,40 @@ public async Task MapOpenApi_ReturnsDocumentWhenPathIsCaseSensitive(string regis
         Assert.Equal(StatusCodes.Status200OK, context.Response.StatusCode);
     }
 
+    [Fact]
+    public async Task MapOpenApi_ShouldRetrieveOptionsInACaseInsensitiveManner()
+    {
+        // Arrange
+        var hostEnvironment = new HostEnvironment() { ApplicationName = nameof(OpenApiEndpointRouteBuilderExtensionsTests) };
+        var serviceProviderIsService = new ServiceProviderIsService();
+        var serviceProvider = CreateServiceProvider("casesensitive", OpenApiSpecVersion.OpenApi2_0);
+        var builder = new DefaultEndpointRouteBuilder(new ApplicationBuilder(serviceProvider));
+        builder.MapOpenApi("/openapi/{documentName}.json");
+        var context = new DefaultHttpContext();
+        var responseBodyStream = new MemoryStream();
+        context.Response.Body = responseBodyStream;
+        context.RequestServices = serviceProvider;
+        context.Request.RouteValues.Add("documentName", "CaseSensitive");
+        var endpoint = builder.DataSources.First().Endpoints[0];
+
+        // Act
+        var requestDelegate = endpoint.RequestDelegate;
+        await requestDelegate(context);
+
+        // Assert
+        Assert.Equal(StatusCodes.Status200OK, context.Response.StatusCode);
+        var responseString = Encoding.UTF8.GetString(responseBodyStream.ToArray());
+
+        // When we receive an OpenAPI document, we use an OptionsMonitor to retrieve named options that equal the requested document name.
+        // This is case-sensitive. If the document doesn't exist, the options monitor return a default instance, in which the OpenAPI version is set to v3.
+        // By setting up a v2 document on the "casesensitive" route and requesting it on "CaseSensitive",
+        // we can test that the we've configured the options monitor to retrieve the options in a case-insensitive manner.
+        // If it is case-sensitive, it would return a default instance with OpenAPI version v3, which would cause this test to fail!
+        // However, if it would return the v2 instance, the test would pass!
+        // For more info, see OpenApiEndpointRouteBuilderExtensions.cs
+        Assert.StartsWith("{\n  \"swagger\": \"2.0\"", responseString);
+    }
+
     [Theory]
     [InlineData("/openapi.json", "application/json;charset=utf-8", false)]
     [InlineData("/openapi.yaml", "text/plain+yaml;charset=utf-8", true)]
@@ -201,7 +236,7 @@ private static void ValidateOpenApiDocument(MemoryStream documentStream, Action<
         action(document);
     }
 
-    private static IServiceProvider CreateServiceProvider(string documentName = Microsoft.AspNetCore.OpenApi.OpenApiConstants.DefaultDocumentName)
+    private static IServiceProvider CreateServiceProvider(string documentName = Microsoft.AspNetCore.OpenApi.OpenApiConstants.DefaultDocumentName, OpenApiSpecVersion openApiSpecVersion = OpenApiSpecVersion.OpenApi3_0)
     {
         var hostEnvironment = new HostEnvironment() { ApplicationName = nameof(OpenApiEndpointRouteBuilderExtensionsTests) };
         var serviceProviderIsService = new ServiceProviderIsService();
@@ -210,7 +245,7 @@ private static IServiceProvider CreateServiceProvider(string documentName = Micr
             .AddSingleton<IHostEnvironment>(hostEnvironment)
             .AddSingleton(CreateApiDescriptionGroupCollectionProvider())
             .AddSingleton<ILoggerFactory>(NullLoggerFactory.Instance)
-            .AddOpenApi(documentName)
+            .AddOpenApi(documentName, x => x.OpenApiVersion = openApiSpecVersion)
             .BuildServiceProvider();
         return serviceProvider;
     }