Add support for custom cancellation error (#683)

Author: dnadoba

Sources/AsyncHTTPClient/HTTPHandler.swift

@@ -688,7 +688,7 @@ extension URL {
 }
 
 protocol HTTPClientTaskDelegate {
-    func cancel()
+    func fail(_ error: Error)
 }
 
 extension HTTPClient {
@@ -780,12 +780,18 @@ extension HTTPClient {
 
         /// Cancels the request execution.
         public func cancel() {
+            self.fail(reason: HTTPClientError.cancelled)
+        }
+
+        /// Cancels the request execution with a custom `Error`.
+        /// - Parameter reason: the error that is used to fail the promise
+        public func fail(reason error: Error) {
             let taskDelegate = self.lock.withLock { () -> HTTPClientTaskDelegate? in
                 self._isCancelled = true
                 return self._taskDelegate
             }
 
-            taskDelegate?.cancel()
+            taskDelegate?.fail(error)
         }
 
         func succeed<Delegate: HTTPClientResponseDelegate>(promise: EventLoopPromise<Response>?,

Sources/AsyncHTTPClient/RequestBag.swift

@@ -394,7 +394,7 @@ final class RequestBag<Delegate: HTTPClientResponseDelegate> {
     }
 }
 
-extension RequestBag: HTTPSchedulableRequest {
+extension RequestBag: HTTPSchedulableRequest, HTTPClientTaskDelegate {
     var tlsConfiguration: TLSConfiguration? {
         self.request.tlsConfiguration
     }
@@ -511,9 +511,3 @@ extension RequestBag: HTTPExecutableRequest {
         }
     }
 }
-
-extension RequestBag: HTTPClientTaskDelegate {
-    func cancel() {
-        self.fail(HTTPClientError.cancelled)
-    }
-}

Tests/AsyncHTTPClientTests/HTTP1ClientChannelHandlerTests.swift

@@ -327,7 +327,7 @@ class HTTP1ClientChannelHandlerTests: XCTestCase {
         XCTAssertNoThrow(try embedded.writeInbound(HTTPClientResponsePart.head(responseHead)))
 
         // canceling the request
-        requestBag.cancel()
+        requestBag.fail(HTTPClientError.cancelled)
         XCTAssertThrowsError(try requestBag.task.futureResult.wait()) {
             XCTAssertEqual($0 as? HTTPClientError, .cancelled)
         }

Tests/AsyncHTTPClientTests/HTTP2ClientRequestHandlerTests.swift

@@ -276,7 +276,7 @@ class HTTP2ClientRequestHandlerTests: XCTestCase {
         XCTAssertNoThrow(try embedded.writeInbound(HTTPClientResponsePart.head(responseHead)))
 
         // canceling the request
-        requestBag.cancel()
+        requestBag.fail(HTTPClientError.cancelled)
         XCTAssertThrowsError(try requestBag.task.futureResult.wait()) {
             XCTAssertEqual($0 as? HTTPClientError, .cancelled)
         }

Tests/AsyncHTTPClientTests/HTTPClientTests+XCTest.swift

@@ -52,6 +52,7 @@ extension HTTPClientTests {
             ("testStreaming", testStreaming),
             ("testFileDownload", testFileDownload),
             ("testFileDownloadError", testFileDownloadError),
+            ("testFileDownloadCustomError", testFileDownloadCustomError),
             ("testRemoteClose", testRemoteClose),
             ("testReadTimeout", testReadTimeout),
             ("testConnectTimeout", testConnectTimeout),

Tests/AsyncHTTPClientTests/HTTPClientTests.swift

@@ -569,6 +569,31 @@ final class HTTPClientTests: XCTestCaseHTTPClientTestsBaseClass {
         XCTAssertEqual(0, progress.receivedBytes)
     }
 
+    func testFileDownloadCustomError() throws {
+        let request = try Request(url: self.defaultHTTPBinURLPrefix + "get")
+        struct CustomError: Equatable, Error {}
+
+        try TemporaryFileHelpers.withTemporaryFilePath { path in
+            let delegate = try FileDownloadDelegate(path: path, reportHead: { task, head in
+                XCTAssertEqual(head.status, .ok)
+                task.fail(reason: CustomError())
+            }, reportProgress: { _, _ in
+                XCTFail("should never be called")
+            })
+            XCTAssertThrowsError(
+                try self.defaultClient.execute(
+                    request: request,
+                    delegate: delegate
+                )
+                .wait()
+            ) { error in
+                XCTAssertEqualTypeAndValue(error, CustomError())
+            }
+
+            XCTAssertFalse(TemporaryFileHelpers.fileExists(path: path))
+        }
+    }
+
     func testRemoteClose() {
         XCTAssertThrowsError(try self.defaultClient.get(url: self.defaultHTTPBinURLPrefix + "close").wait()) {
             XCTAssertEqual($0 as? HTTPClientError, .remoteConnectionClosed)

Tests/AsyncHTTPClientTests/HTTPConnectionPoolTests.swift

@@ -334,7 +334,7 @@ class HTTPConnectionPoolTests: XCTestCase {
 
         pool.executeRequest(requestBag)
         XCTAssertNoThrow(try eventLoop.scheduleTask(in: .seconds(1)) {}.futureResult.wait())
-        requestBag.cancel()
+        requestBag.fail(HTTPClientError.cancelled)
 
         XCTAssertThrowsError(try requestBag.task.futureResult.wait()) {
             XCTAssertEqual($0 as? HTTPClientError, .cancelled)

Tests/AsyncHTTPClientTests/RequestBagTests.swift

@@ -220,7 +220,7 @@ final class RequestBagTests: XCTestCase {
         XCTAssert(bag.eventLoop === embeddedEventLoop)
 
         let executor = MockRequestExecutor(eventLoop: embeddedEventLoop)
-        bag.cancel()
+        bag.fail(HTTPClientError.cancelled)
 
         bag.willExecuteRequest(executor)
         XCTAssertTrue(executor.isCancelled, "The request bag, should call cancel immediately on the executor")
@@ -301,7 +301,7 @@ final class RequestBagTests: XCTestCase {
         bag.fail(MyError())
         XCTAssertEqual(delegate.hitDidReceiveError, 1)
 
-        bag.cancel()
+        bag.fail(HTTPClientError.cancelled)
         XCTAssertEqual(delegate.hitDidReceiveError, 1)
 
         XCTAssertThrowsError(try bag.task.futureResult.wait()) {
@@ -342,7 +342,7 @@ final class RequestBagTests: XCTestCase {
         XCTAssertEqual(delegate.hitDidSendRequestHead, 1)
         XCTAssertEqual(delegate.hitDidSendRequest, 1)
 
-        bag.cancel()
+        bag.fail(HTTPClientError.cancelled)
         XCTAssertTrue(executor.isCancelled, "The request bag, should call cancel immediately on the executor")
 
         XCTAssertThrowsError(try bag.task.futureResult.wait()) {
@@ -376,7 +376,7 @@ final class RequestBagTests: XCTestCase {
         bag.requestWasQueued(queuer)
 
         XCTAssertEqual(queuer.hitCancelCount, 0)
-        bag.cancel()
+        bag.fail(HTTPClientError.cancelled)
         XCTAssertEqual(queuer.hitCancelCount, 1)
 
         XCTAssertThrowsError(try bag.task.futureResult.wait()) {
@@ -445,9 +445,9 @@ final class RequestBagTests: XCTestCase {
         let executor = MockRequestExecutor(eventLoop: embeddedEventLoop)
         executor.runRequest(bag)
 
-        // This simulates a race between the user cancelling the task (which invokes `RequestBag.cancel`) and the
+        // This simulates a race between the user cancelling the task (which invokes `RequestBag.fail(_:)`) and the
         // call to `resumeRequestBodyStream` (which comes from the `Channel` event loop and so may have to hop.
-        bag.cancel()
+        bag.fail(HTTPClientError.cancelled)
         bag.resumeRequestBodyStream()
 
         XCTAssertEqual(executor.isCancelled, true)