Add an explicit test to verify we don't loose data if we receive an end.

Author: fabianfett

Diff for: Sources/AsyncHTTPClient/ConnectionPool/HTTPRequestStateMachine+Demand.swift

@@ -99,9 +99,9 @@ extension HTTPRequestStateMachine {
             // If the connection to a server is closed, NIO will forward all outstanding
             // `channelRead`s without waiting for a next `context.read` call. After all
             // `channelRead`s are delivered, we will also see a `channelReadComplete` call. After
-            // this has happened, we know that we will get a channelInactive, which will fail the
-            // request. Since the request is doomed anyway, we can just drop the already buffered
-            // bytes here.
+            // this has happened, we know that we will get a channelInactive or further
+            // `channelReads`. If the request ever gets to an `.end` all buffered data will be
+            // forwarded to the user.
 
             case .waitingForRead,
                  .waitingForDemand,

Diff for: Tests/AsyncHTTPClientTests/HTTPRequestStateMachineTests+XCTest.swift

@@ -59,6 +59,7 @@ extension HTTPRequestStateMachineTests {
             ("testFailHTTPRequestWithContentLengthBecauseOfChannelInactiveWaitingForDemand", testFailHTTPRequestWithContentLengthBecauseOfChannelInactiveWaitingForDemand),
             ("testFailHTTPRequestWithContentLengthBecauseOfChannelInactiveWaitingForRead", testFailHTTPRequestWithContentLengthBecauseOfChannelInactiveWaitingForRead),
             ("testFailHTTPRequestWithContentLengthBecauseOfChannelInactiveWaitingForReadAndDemand", testFailHTTPRequestWithContentLengthBecauseOfChannelInactiveWaitingForReadAndDemand),
+            ("testFailHTTPRequestWithContentLengthBecauseOfChannelInactiveWaitingForReadAndDemandMultipleTimes", testFailHTTPRequestWithContentLengthBecauseOfChannelInactiveWaitingForReadAndDemandMultipleTimes),
         ]
     }
 }

Diff for: Tests/AsyncHTTPClientTests/HTTPRequestStateMachineTests.swift

@@ -619,6 +619,39 @@ class HTTPRequestStateMachineTests: XCTestCase {
         XCTAssertEqual(state.channelReadComplete(), .wait)
         XCTAssertEqual(state.channelInactive(), .failRequest(HTTPClientError.remoteConnectionClosed, .none))
     }
+
+    func testFailHTTPRequestWithContentLengthBecauseOfChannelInactiveWaitingForReadAndDemandMultipleTimes() {
+        var state = HTTPRequestStateMachine(isChannelWritable: true, ignoreUncleanSSLShutdown: false)
+        let requestHead = HTTPRequestHead(version: .http1_1, method: .GET, uri: "/")
+        let metadata = RequestFramingMetadata(connectionClose: false, body: .none)
+        XCTAssertEqual(state.startRequest(head: requestHead, metadata: metadata), .sendRequestHead(requestHead, startBody: false))
+
+        let responseHead = HTTPResponseHead(version: .http1_1, status: .ok, headers: ["Content-Length": "50"])
+        let body = ByteBuffer(string: "foo bar")
+        XCTAssertEqual(state.channelRead(.head(responseHead)), .forwardResponseHead(responseHead, pauseRequestBodyStream: false))
+        XCTAssertEqual(state.demandMoreResponseBodyParts(), .wait)
+        XCTAssertEqual(state.channelReadComplete(), .wait)
+        XCTAssertEqual(state.read(), .read)
+        XCTAssertEqual(state.channelRead(.body(body)), .wait)
+        XCTAssertEqual(state.channelReadComplete(), .forwardResponseBodyParts([body]))
+
+        let part1 = ByteBuffer(string: "baz lightyear")
+        XCTAssertEqual(state.channelRead(.body(part1)), .wait)
+        XCTAssertEqual(state.channelReadComplete(), .wait)
+
+        let part2 = ByteBuffer(string: "nearly last")
+        XCTAssertEqual(state.channelRead(.body(part2)), .wait)
+        XCTAssertEqual(state.channelReadComplete(), .wait)
+
+        let part3 = ByteBuffer(string: "final message")
+        XCTAssertEqual(state.channelRead(.body(part3)), .wait)
+        XCTAssertEqual(state.channelReadComplete(), .wait)
+
+        XCTAssertEqual(state.channelRead(.end(nil)), .succeedRequest(.close, [part1, part2, part3]))
+        XCTAssertEqual(state.channelReadComplete(), .wait)
+
+        XCTAssertEqual(state.channelInactive(), .wait)
+    }
 }
 
 extension HTTPRequestStateMachine.Action: Equatable {