feat: HTTP Status 204 should halt stream (#59)

Author: keelerm84

ContractTestService/Sources/ContractTestService/main.swift

@@ -5,7 +5,7 @@ import LDSwiftEventSource
 
 struct StatusResp: Encodable {
     let name = "swift-eventsource"
-    let capabilities = ["comments", "headers", "last-event-id", "post", "read-timeout", "report"]
+    let capabilities = ["server-directed-shutdown-request", "comments", "headers", "last-event-id", "post", "read-timeout", "report"]
 }
 
 struct CreateStreamReq: Decodable {

Source/LDSwiftEventSource.swift

@@ -104,9 +104,19 @@ public class EventSource {
         /**
          An error handler that is called when an error occurs and can shut down the client in response.
 
-         The default error handler will always attempt to reconnect on an error, unless `EventSource.stop()` is called.
+         The default error handler will always attempt to reconnect on an
+         error, unless `EventSource.stop()` is called or the error code is 204.
          */
-        public var connectionErrorHandler: ConnectionErrorHandler = { _ in .proceed }
+        public var connectionErrorHandler: ConnectionErrorHandler = { error in
+            guard let unsuccessfulResponseError = error as? UnsuccessfulResponseError
+            else { return .proceed }
+
+            let responseCode: Int = unsuccessfulResponseError.responseCode
+            if 204 == responseCode {
+                return .shutdown
+            }
+            return .proceed
+        }
 
         /// Create a new configuration with an `EventHandler` and a `URL`
         public init(handler: EventHandler, url: URL) {
@@ -288,14 +298,15 @@ class EventSourceDelegate: NSObject, URLSessionDataDelegate {
 
         // swiftlint:disable:next force_cast
         let httpResponse = response as! HTTPURLResponse
-        if (200..<300).contains(httpResponse.statusCode) {
+        let statusCode = httpResponse.statusCode
+        if (200..<300).contains(statusCode) && statusCode != 204 {
             reconnectionTimer.connectedTime = Date()
             readyState = .open
             config.handler.onOpened()
             completionHandler(.allow)
         } else {
-            logger.log(.info, "Unsuccessful response: %d", httpResponse.statusCode)
-            if dispatchError(error: UnsuccessfulResponseError(responseCode: httpResponse.statusCode)) == .shutdown {
+            logger.log(.info, "Unsuccessful response: %d", statusCode)
+            if dispatchError(error: UnsuccessfulResponseError(responseCode: statusCode)) == .shutdown {
                 logger.log(.info, "Connection has been explicitly shut down by error handler")
                 readyState = .shutdown
             }

Tests/LDSwiftEventSourceTests.swift

@@ -207,7 +207,7 @@ final class LDSwiftEventSourceTests: XCTestCase {
         XCTAssertEqual(handler.request.allHTTPHeaderFields?["X-LD-Header"], "def")
         es.stop()
     }
-    
+
     func testStartRequestIsNotReentrant() {
         var config = EventSource.Config(handler: mockHandler, url: URL(string: "http://example.com")!)
         config.urlSessionConfiguration = sessionWithMockProtocol()
@@ -349,6 +349,47 @@ final class LDSwiftEventSourceTests: XCTestCase {
         // Error should not have been given to the handler
         mockHandler.events.expectNoEvent()
     }
+
+    func testShutdownBy204Response() {
+        var config = EventSource.Config(handler: mockHandler, url: URL(string: "http://example.com")!)
+        config.urlSessionConfiguration = sessionWithMockProtocol()
+        config.reconnectTime = 0.1
+
+        let es = EventSource(config: config)
+        es.start()
+
+        let handler = MockingProtocol.requested.expectEvent()
+        handler.respond(statusCode: 204)
+
+        MockingProtocol.requested.expectNoEvent(within: 1.0)
+
+        es.stop()
+        // Error should not have been given to the handler
+        mockHandler.events.expectNoEvent()
+    }
+
+    func testCanOverride204DefaultBehavior() {
+        var config = EventSource.Config(handler: mockHandler, url: URL(string: "http://example.com")!)
+        config.urlSessionConfiguration = sessionWithMockProtocol()
+        config.reconnectTime = 0.1
+        config.connectionErrorHandler = { err in
+            if let responseErr = err as? UnsuccessfulResponseError {
+                XCTAssertEqual(responseErr.responseCode, 204)
+            } else {
+                XCTFail("Expected UnsuccessfulResponseError to be given to handler")
+            }
+            return .shutdown
+        }
+        let es = EventSource(config: config)
+        es.start()
+        let handler = MockingProtocol.requested.expectEvent()
+        handler.respond(statusCode: 204)
+        // Expect the client not to reconnect
+        MockingProtocol.requested.expectNoEvent(within: 1.0)
+        es.stop()
+        // Error should not have been given to the handler
+        mockHandler.events.expectNoEvent()
+    }
 #endif
 }