Use spawnHybrid for the stub server (#700)

Move the in-process stub server from `test/io/utils.dart` to
`test/stub_server.dart` as a `hybridMain`. This will allow spawning the
server from the browser tests as well.

The browser tests still do not work against this server. Separate out
the change in how the server is started from the (potential) other
changes with fixes.

Update tests to use the new pattern - they call `startServer` and wait
for the `serverUrl`. No explicit teardown is needed because the
`spawnHybrid` call gets an implicit `addTearDown` which kills the
isolate.

Remove `test/io/utils.dart` entirely. Inline the definition of
`throwsSocketException` at the single use site.
Make the `message` argument to the other copy of `throwsClientException`
optional and use it in place of the version that had been in
`test/io/utils.dart`.

Author: natebosch

pubspec.yaml

@@ -16,4 +16,5 @@ dev_dependencies:
   fake_async: ^1.2.0
   lints: ^1.0.0
   shelf: ^1.1.0
+  stream_channel: ^2.1.0
   test: ^1.16.0

test/io/client_test.dart

@@ -10,12 +10,13 @@ import 'package:http/http.dart' as http;
 import 'package:http/io_client.dart' as http_io;
 import 'package:test/test.dart';
 
-import 'utils.dart';
+import '../utils.dart';
 
 void main() {
-  setUp(startServer);
-
-  tearDown(stopServer);
+  late Uri serverUrl;
+  setUpAll(() async {
+    serverUrl = await startServer();
+  });
 
   test('#send a StreamedRequest', () async {
     var client = http.Client();
@@ -101,7 +102,7 @@ void main() {
     request.headers[HttpHeaders.contentTypeHeader] =
         'application/json; charset=utf-8';
 
-    expect(client.send(request), throwsSocketException);
+    expect(client.send(request), throwsA(isA<SocketException>()));
 
     request.sink.add('{"hello": "world"}'.codeUnits);
     request.sink.close();

test/io/http_test.dart

@@ -7,14 +7,15 @@
 import 'package:http/http.dart' as http;
 import 'package:test/test.dart';
 
-import 'utils.dart';
+import '../utils.dart';
 
 void main() {
-  group('http.', () {
-    setUp(startServer);
-
-    tearDown(stopServer);
+  late Uri serverUrl;
+  setUpAll(() async {
+    serverUrl = await startServer();
+  });
 
+  group('http.', () {
     test('head', () async {
       var response = await http.head(serverUrl);
       expect(response.statusCode, equals(200));
@@ -408,7 +409,7 @@ void main() {
     });
 
     test('read throws an error for a 4** status code', () {
-      expect(http.read(serverUrl.resolve('/error')), throwsClientException);
+      expect(http.read(serverUrl.resolve('/error')), throwsClientException());
     });
 
     test('readBytes', () async {
@@ -434,7 +435,7 @@ void main() {
 
     test('readBytes throws an error for a 4** status code', () {
       expect(
-          http.readBytes(serverUrl.resolve('/error')), throwsClientException);
+          http.readBytes(serverUrl.resolve('/error')), throwsClientException());
     });
   });
 }

test/io/multipart_test.dart

@@ -10,7 +10,7 @@ import 'package:http/http.dart' as http;
 import 'package:path/path.dart' as path;
 import 'package:test/test.dart';
 
-import 'utils.dart';
+import '../utils.dart';
 
 void main() {
   late Directory tempDir;

test/io/request_test.dart

@@ -7,12 +7,13 @@
 import 'package:http/http.dart' as http;
 import 'package:test/test.dart';
 
-import 'utils.dart';
+import '../utils.dart';
 
 void main() {
-  setUp(startServer);
-
-  tearDown(stopServer);
+  late Uri serverUrl;
+  setUpAll(() async {
+    serverUrl = await startServer();
+  });
 
   test('send happy case', () async {
     final request = http.Request('GET', serverUrl)

test/io/streamed_request_test.dart

@@ -9,12 +9,13 @@ import 'dart:convert';
 import 'package:http/http.dart' as http;
 import 'package:test/test.dart';
 
-import 'utils.dart';
+import '../utils.dart';
 
 void main() {
-  setUp(startServer);
-
-  tearDown(stopServer);
+  late Uri serverUrl;
+  setUpAll(() async {
+    serverUrl = await startServer();
+  });
 
   group('contentLength', () {
     test('controls the Content-Length header', () async {

test/io/utils.dart

@@ -0,0 +1,100 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:io';
+
+import 'package:http/http.dart';
+import 'package:http/src/utils.dart';
+import 'package:stream_channel/stream_channel.dart';
+
+void hybridMain(StreamChannel<dynamic> channel) async {
+  final server = await HttpServer.bind('localhost', 0);
+  final url = Uri.http('localhost:${server.port}', '');
+  server.listen((request) async {
+    var path = request.uri.path;
+    var response = request.response;
+
+    if (path == '/error') {
+      response
+        ..statusCode = 400
+        ..contentLength = 0;
+      unawaited(response.close());
+      return;
+    }
+
+    if (path == '/loop') {
+      var n = int.parse(request.uri.query);
+      response
+        ..statusCode = 302
+        ..headers.set('location', url.resolve('/loop?${n + 1}').toString())
+        ..contentLength = 0;
+      unawaited(response.close());
+      return;
+    }
+
+    if (path == '/redirect') {
+      response
+        ..statusCode = 302
+        ..headers.set('location', url.resolve('/').toString())
+        ..contentLength = 0;
+      unawaited(response.close());
+      return;
+    }
+
+    if (path == '/no-content-length') {
+      response
+        ..statusCode = 200
+        ..contentLength = -1
+        ..write('body');
+      unawaited(response.close());
+      return;
+    }
+
+    var requestBodyBytes = await ByteStream(request).toBytes();
+    var encodingName = request.uri.queryParameters['response-encoding'];
+    var outputEncoding =
+        encodingName == null ? ascii : requiredEncodingForCharset(encodingName);
+
+    response.headers.contentType =
+        ContentType('application', 'json', charset: outputEncoding.name);
+    response.headers.set('single', 'value');
+
+    dynamic requestBody;
+    if (requestBodyBytes.isEmpty) {
+      requestBody = null;
+    } else if (request.headers.contentType?.charset != null) {
+      var encoding =
+          requiredEncodingForCharset(request.headers.contentType!.charset!);
+      requestBody = encoding.decode(requestBodyBytes);
+    } else {
+      requestBody = requestBodyBytes;
+    }
+
+    final headers = <String, List<String>>{};
+
+    request.headers.forEach((name, values) {
+      // These headers are automatically generated by dart:io, so we don't
+      // want to test them here.
+      if (name == 'cookie' || name == 'host') return;
+
+      headers[name] = values;
+    });
+
+    var content = <String, dynamic>{
+      'method': request.method,
+      'path': request.uri.path,
+      if (requestBody != null) 'body': requestBody,
+      'headers': headers,
+    };
+
+    var body = json.encode(content);
+    response
+      ..contentLength = body.length
+      ..write(body);
+    unawaited(response.close());
+  });
+  channel.sink.add(server.port);
+}

test/stub_server.dart

@@ -110,5 +110,19 @@ class _BodyMatches extends Matcher {
 /// [http.ClientException] with the given [message].
 ///
 /// [message] can be a String or a [Matcher].
-Matcher throwsClientException(String message) => throwsA(
-    isA<http.ClientException>().having((e) => e.message, 'message', message));
+Matcher throwsClientException([String? message]) {
+  var exception = isA<http.ClientException>();
+  if (message != null) {
+    exception = exception.having((e) => e.message, 'message', message);
+  }
+  return throwsA(exception);
+}
+
+/// Spawn an isolate in the test runner with an http server.
+///
+/// The server isolate will be killed on teardown.
+Future<Uri> startServer() async {
+  final channel = spawnHybridUri(Uri(path: '/test/stub_server.dart'));
+  final port = await channel.stream.first as int;
+  return Uri.http('localhost:$port', '');
+}