Add a complex reload test that rebases the root script path three times.

runtime/observatory/tests/service/complex_reload_test.dart

+// Copyright (c) 2016, 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.
+// VMOptions=--error_on_bad_type --error_on_bad_override
+
+import 'test_helper.dart';
+import 'dart:async';
+import 'dart:developer';
+import 'dart:isolate' as I;
+import 'dart:io';
+import 'service_test_common.dart';
+import 'package:observatory/service.dart';
+import 'package:unittest/unittest.dart';
+
+testMain() async {
+  debugger();  // Stop here.
+  // Spawn the child isolate.
+  I.Isolate isolate =
+      await I.Isolate.spawnUri(Uri.parse('complex_reload/v1/main.dart'),
+                               [],
+                               null);
+  print(isolate);
+  debugger();
+}
+
+// Directory that we are running in.
+String directory = Platform.pathSeparator +
+    Platform.script.pathSegments.sublist(
+        0,
+        Platform.script.pathSegments.length - 1).join(Platform.pathSeparator);
+
+Future<String> invokeTest(Isolate isolate) async {
+  await isolate.reload();
+  Library lib = isolate.rootLibrary;
+  await lib.load();
+  Instance result = await lib.evaluate('test()');
+  expect(result.isString, isTrue);
+  return result.valueAsString;
+}
+
+var tests = [
+  // Stopped at 'debugger' statement.
+  hasStoppedAtBreakpoint,
+  // Resume the isolate into the while loop.
+  resumeIsolate,
+  // Stop at 'debugger' statement.
+  hasStoppedAtBreakpoint,
+  (Isolate mainIsolate) async {
+    // Grab the VM.
+    VM vm = mainIsolate.vm;
+    await vm.reloadIsolates();
+    expect(vm.isolates.length, 2);
+
+    // Find the slave isolate.
+    Isolate slaveIsolate =
+        vm.isolates.firstWhere((Isolate i) => i != mainIsolate);
+    expect(slaveIsolate, isNotNull);
+
+    // Invoke test in v1.
+    String v1 = await invokeTest(slaveIsolate);
+    expect(v1, 'apple');
+
+    // Reload to v2.
+    var response = await slaveIsolate.reloadSources(
+       rootLibUri: '$directory/complex_reload/v2/main.dart',
+    );
+    expect(response['success'], isTrue);
+
+    // Invoke test in v2.
+    String v2 = await invokeTest(slaveIsolate);
+    expect(v2, 'banana');
+
+    // Reload to v3.
+    response = await slaveIsolate.reloadSources(
+      rootLibUri: '$directory/complex_reload/v3/main.dart',
+    );
+    expect(response['success'], isTrue);
+
+    // Invoke test in v3.
+    String v3 = await invokeTest(slaveIsolate);
+    expect(v3, 'cabbage');
+  }
+];
+
+main(args) => runIsolateTests(args, tests, testeeConcurrent: testMain);