Add unit tests for NWWaitingHandler, closes #589 (#702)

* Add unit tests for NWWaitingHandler

Motivation:

Closes #589. Since we already have a public initializer for
NIOTSNetworkEvents.WaitingForConnectivity, we should add unit tests for
the handler now that it's straightforward.

Modifications:

The tests are in their own file `Tests/NWWaitingHandlerTests.swift`.

* Bump swift-nio-transport-services to 1.13.0

* [email protected]

* Apply suggestions from code review

Co-authored-by: David Nadoba <[email protected]>

---------

Co-authored-by: David Nadoba <[email protected]>

Author: natikgadzhi

Tests/AsyncHTTPClientTests/NWWaitingHandlerTests.swift

@@ -0,0 +1,79 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the AsyncHTTPClient open source project
+//
+// Copyright (c) 2023 Apple Inc. and the AsyncHTTPClient project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of AsyncHTTPClient project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+#if canImport(Network)
+@testable import AsyncHTTPClient
+import Network
+import NIOCore
+import NIOEmbedded
+import NIOSSL
+import NIOTransportServices
+import XCTest
+
+@available(OSX 10.14, iOS 12.0, tvOS 12.0, watchOS 6.0, *)
+class NWWaitingHandlerTests: XCTestCase {
+    class MockRequester: HTTPConnectionRequester {
+        var waitingForConnectivityCalled = false
+        var connectionID: AsyncHTTPClient.HTTPConnectionPool.Connection.ID?
+        var transientError: NWError?
+
+        func http1ConnectionCreated(_: AsyncHTTPClient.HTTP1Connection) {}
+
+        func http2ConnectionCreated(_: AsyncHTTPClient.HTTP2Connection, maximumStreams: Int) {}
+
+        func failedToCreateHTTPConnection(_: AsyncHTTPClient.HTTPConnectionPool.Connection.ID, error: Error) {}
+
+        func waitingForConnectivity(_ connectionID: AsyncHTTPClient.HTTPConnectionPool.Connection.ID, error: Error) {
+            self.waitingForConnectivityCalled = true
+            self.connectionID = connectionID
+            self.transientError = error as? NWError
+        }
+    }
+
+    func testWaitingHandlerInvokesWaitingForConnectivity() {
+        let requester = MockRequester()
+        let connectionID: AsyncHTTPClient.HTTPConnectionPool.Connection.ID = 1
+        let waitingEventHandler = NWWaitingHandler(requester: requester, connectionID: connectionID)
+        let embedded = EmbeddedChannel(handlers: [waitingEventHandler])
+
+        embedded.pipeline.fireUserInboundEventTriggered(NIOTSNetworkEvents.WaitingForConnectivity(transientError: .dns(1)))
+
+        XCTAssertTrue(requester.waitingForConnectivityCalled, "Expected the handler to invoke .waitingForConnectivity on the requester")
+        XCTAssertEqual(requester.connectionID, connectionID, "Expected the handler to pass connectionID to requester")
+        XCTAssertEqual(requester.transientError, NWError.dns(1))
+    }
+
+    func testWaitingHandlerDoesNotInvokeWaitingForConnectionOnUnrelatedErrors() {
+        let requester = MockRequester()
+        let waitingEventHandler = NWWaitingHandler(requester: requester, connectionID: 1)
+        let embedded = EmbeddedChannel(handlers: [waitingEventHandler])
+        embedded.pipeline.fireUserInboundEventTriggered(NIOTSNetworkEvents.BetterPathAvailable())
+
+        XCTAssertFalse(requester.waitingForConnectivityCalled, "Should not call .waitingForConnectivity on unrelated events")
+    }
+
+    func testWaitingHandlerPassesTheEventDownTheContext() {
+        let requester = MockRequester()
+        let waitingEventHandler = NWWaitingHandler(requester: requester, connectionID: 1)
+        let tlsEventsHandler = TLSEventsHandler(deadline: nil)
+        let embedded = EmbeddedChannel(handlers: [waitingEventHandler, tlsEventsHandler])
+
+        embedded.pipeline.fireErrorCaught(NIOSSLError.handshakeFailed(BoringSSLError.wantConnect))
+        XCTAssertThrowsError(try XCTUnwrap(tlsEventsHandler.tlsEstablishedFuture).wait()) {
+            XCTAssertEqualTypeAndValue($0, NIOSSLError.handshakeFailed(BoringSSLError.wantConnect))
+        }
+    }
+}
+
+#endif