Add tests

Author: Anna Gringauze

dwds/CHANGELOG.md

@@ -3,6 +3,7 @@
 - Return empty library from `ChromeProxyService.getObject` for
   libraries present in medatata but not lodaded at runtime.
 - Log failures to load kernel during expression evaluation.
+- Limit simultaneous connections to asset server to prevent broken sockets.
 
 ## 11.1.1
 

dwds/test/handlers/asset_handler_test.dart

@@ -0,0 +1,77 @@
+// Copyright (c) 2020, 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.
+
+// @dart = 2.9
+
+import 'dart:io';
+
+import 'package:http/http.dart' as http;
+import 'package:http/io_client.dart';
+import 'package:shelf/shelf.dart';
+import 'package:shelf_proxy/shelf_proxy.dart';
+import 'package:test/test.dart';
+
+import '../fixtures/context.dart';
+import '../fixtures/utilities.dart';
+
+void main() {
+  group('Asset handler', () {
+    final context = TestContext();
+    Handler assetHandler;
+    http.Client client;
+
+    setUpAll(() async {
+      await context.setUp(enableExpressionEvaluation: true);
+
+      client = IOClient(HttpClient()
+        ..maxConnectionsPerHost = 200
+        ..idleTimeout = const Duration(seconds: 30)
+        ..connectionTimeout = const Duration(seconds: 30));
+
+      var assetServerPort = daemonPort(context.workingDirectory);
+      var pathToServe = context.pathToServe;
+
+      assetHandler = proxyHandler(
+          'http://localhost:$assetServerPort/$pathToServe/',
+          client: client);
+    });
+
+    tearDownAll(() {
+      client.close();
+    });
+
+    Future<void> readAsString(String path) async {
+      var request = Request('GET', Uri.parse('http://foo:0000/$path'));
+      var response = await assetHandler(request);
+      var result = await response.readAsString();
+      expect(result, isNotNull, reason: 'Failed to read $path');
+    }
+
+    Future<void> readAsBytes(String path) async {
+      var request = Request('GET', Uri.parse('http://foo:0000/$path'));
+      var response = await assetHandler(request);
+      var result = response.read().toList();
+      expect(result, isNotNull, reason: 'Failed to read $path');
+    }
+
+    test('can read dill files', () async {
+      var path = 'hello_world/main.unsound.ddc.full.dill';
+      await readAsBytes(path);
+    });
+
+    test('can read large number of resources simultaneously', () async {
+      final n = 1000;
+      var futures = [
+        for (var i = 0; i < n; i++)
+          readAsString('hello_world/main.unsound.ddc.js.map'),
+        for (var i = 0; i < n; i++)
+          readAsString('hello_world/main.unsound.ddc.js'),
+        for (var i = 0; i < n; i++)
+          readAsBytes('hello_world/main.unsound.ddc.full.dill'),
+      ];
+
+      await expectLater(Future.wait(futures), completes);
+    });
+  });
+}