Extract individual accepts headers and check for text/event-stream

Author: Tobias Mønster

Lib.AspNetCore.ServerSentEvents/ServerSentEventsMiddleware.cs

@@ -125,8 +125,8 @@ private bool CheckAcceptHeader(IHeaderDictionary requestHeaders)
             {
                 return !_serverSentEventsOptions.RequireAcceptHeader;
             }
-
-            if (requestHeaders[Constants.ACCEPT_HTTP_HEADER].Any(acceptHeaderValue => acceptHeaderValue == Constants.SSE_CONTENT_TYPE))
+            
+            if (requestHeaders.GetCommaSeparatedValues(Constants.ACCEPT_HTTP_HEADER).Any(acceptHeaderValue => acceptHeaderValue == Constants.SSE_CONTENT_TYPE))
             {
                 return true;
             }

Test.AspNetCore.ServerSentEvents/Unit/Middleware/HandshakeTests.cs

@@ -72,6 +72,29 @@ public async Task Invoke_SseRequest_CallsOnPrepareAccept()
 
             onPrepareAcceptMock.Verify(m => m(It.IsAny<HttpResponse>()), Times.Once);
         }
+        
+        [Fact]
+        public async Task Invoke_SseRequestWithMultipleAcceptHeadersWithEventStreamAcceptHeader_Accepts()
+        {
+            ServerSentEventsMiddleware<ServerSentEventsService> serverSentEventsMiddleware = SubjectUnderTestHelper.PrepareServerSentEventsMiddleware();
+            HttpContext context = SubjectUnderTestHelper.PrepareHttpContext(acceptHeaderValue: SSE_CONTENT_TYPE+",text/html");
+
+            await serverSentEventsMiddleware.Invoke(context, null);
+
+            Assert.Equal(SSE_CONTENT_TYPE, context.Response.ContentType);
+        }
+        
+        [Fact]
+        public async Task Invoke_SseRequestWithMultipleAcceptHeadersWithNotEventStreamAcceptHeader_DoesNotAccept()
+        {
+            ServerSentEventsMiddleware<ServerSentEventsService> serverSentEventsMiddleware = SubjectUnderTestHelper.PrepareServerSentEventsMiddleware();
+            HttpContext context = SubjectUnderTestHelper.PrepareHttpContext(acceptHeaderValue: "text/plain,text/html");
+
+            await serverSentEventsMiddleware.Invoke(context, null);
+
+            Assert.Null(context.Response.ContentType);
+        }
+        
         #endregion
     }
 }