Add support for multi-roots

pkg/front_end/test/src/multi_root_file_system_test.dart

+// Copyright (c) 2017, 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.
+
+library front_end.test.src.multi_root_file_system.dart;
+
+import 'dart:async';
+
+import 'package:front_end/memory_file_system.dart';
+import 'package:front_end/src/multi_root_file_system.dart';
+
+import 'package:test/test.dart';
+
+var root = Uri.parse('file:///');
+
+main() {
+  var memoryFs;
+  var rootUris;
+  var multiRoot;
+
+  write(String multiRoot, String path) {
+    var realPath = multiRoot == '' ? path : '$multiRoot/$path';
+    var uri = root.resolve(realPath);
+    memoryFs.entityForUri(uri).writeAsStringSync('$uri');
+  }
+
+  Future<String> read(String uri) =>
+      multiRoot.entityForUri(Uri.parse(uri)).readAsString();
+
+  Future<bool> exists(String uri) =>
+      multiRoot.entityForUri(Uri.parse(uri)).exists();
+
+  Future<String> effectiveUriOf(String uri) async =>
+      (await multiRoot.entityForUri(Uri.parse(uri)).delegate).uri.toString();
+
+  setUp(() {
+    memoryFs = new MemoryFileSystem(root);
+    rootUris = ['r1', 'r2/', 'A/B/', ''].map((r) => root.resolve(r)).toList();
+    multiRoot = new MultiRootFileSystem('multi-root', rootUris, memoryFs);
+  });
+
+  test('roots are normalized', () async {
+    expect(multiRoot.roots.map((x) => x.path).toList(),
+        ['/r1/', '/r2/', '/A/B/', '/']);
+  });
+
+  test('file URIs are not converted', () async {
+    write('r1', 'a/b/1.dart');
+    write('', 'a/b/1.dart');
+    expect(await effectiveUriOf('file:///a/b/1.dart'), 'file:///a/b/1.dart');
+  });
+
+  test('only URIs with the marker scheme are converted', () async {
+    write('r1', 'a/b/2.dart');
+    expect(await effectiveUriOf('multi-root:///a/b/2.dart'),
+        'file:///r1/a/b/2.dart');
+    expect(await effectiveUriOf('foo-root:///a/b/2.dart'),
+        'foo-root:///a/b/2.dart');
+  });
+
+  test('roots are visited in declaration order (match first root)', () async {
+    write('r1', 'a/3.dart');
+    write('r2', 'a/3.dart');
+    write('', 'a/3.dart');
+    expect(
+        await effectiveUriOf('multi-root:///a/3.dart'), 'file:///r1/a/3.dart');
+  });
+
+  test('roots are visited in declaration order (match second root)', () async {
+    write('r2', 'a/4.dart');
+    write('', 'a/4.dart');
+    expect(
+        await effectiveUriOf('multi-root:///a/4.dart'), 'file:///r2/a/4.dart');
+  });
+
+  test('roots are visited in declaration order (match last root)', () async {
+    write('', 'a/5.dart');
+    expect(await effectiveUriOf('multi-root:///a/5.dart'), 'file:///a/5.dart');
+  });
+
+  test('operations are forwarded to the correct target', () async {
+    write('r1', 'a/6.dart');
+    write('r2', 'a/6.dart');
+    write('r2', 'a/7.dart');
+
+    expect(await exists('multi-root:///a/6.dart'), isTrue);
+    expect(await read('multi-root:///a/6.dart'), 'file:///r1/a/6.dart');
+
+    expect(await exists('multi-root:///a/7.dart'), isTrue);
+    expect(await read('multi-root:///a/7.dart'), 'file:///r2/a/7.dart');
+    expect(await exists('file:///r2/a/7.dart'), isTrue);
+    expect(await read('file:///r2/a/7.dart'), 'file:///r2/a/7.dart');
+
+    expect(await exists('multi-root:///a/8.dart'), isFalse);
+  });
+
+  test('multi-root expects absolute paths', () async {
+    write('A/B', 'a/8.dart');
+
+    expect(
+        await effectiveUriOf('multi-root:///a/8.dart'), 'file:///A/B/a/8.dart');
+    expect(await effectiveUriOf('multi-root:///../B/a/8.dart'),
+        'multi-root:///B/a/8.dart');
+
+    // Embedding the full absolute path after a few `..` gets resolved because
+    // we have also included '' as a root.
+    expect(await effectiveUriOf('multi-root:///../A/B/a/8.dart'),
+        'file:///A/B/a/8.dart');
+    expect(await effectiveUriOf('multi-root:///../../A/B/a/8.dart'),
+        'file:///A/B/a/8.dart');
+
+    // If we remove '' as a root, those URIs are not resolved.
+    multiRoot =
+        new MultiRootFileSystem('multi-root', [root.resolve('A/B/')], memoryFs);
+    expect(await effectiveUriOf('multi-root:///../A/B/a/8.dart'),
+        'multi-root:///A/B/a/8.dart');
+    expect(await effectiveUriOf('multi-root:///../../A/B/a/8.dart'),
+        'multi-root:///A/B/a/8.dart');
+  });
+}