add an --enable-vmservice flag (#50663)

packages/flutter_tools/bin/fuchsia_tester.dart

@@ -142,7 +142,8 @@ Future<void> run(List<String> args) async {
       tests[source] = dill;
     }
 
-    exitCode = await runTests(
+    // TODO(dnfield): This should be injected.
+    exitCode = await const FlutterTestRunner().runTests(
       const TestWrapper(),
       tests.keys.toList(),
       workDir: testDirectory,

packages/flutter_tools/lib/src/commands/test.dart

@@ -27,6 +27,7 @@ class TestCommand extends FastFlutterCommand {
   TestCommand({
     bool verboseHelp = false,
     this.testWrapper = const TestWrapper(),
+    this.testRunner = const FlutterTestRunner(),
   }) : assert(testWrapper != null) {
     requiresPubspecYaml();
     usesPubOption();
@@ -110,6 +111,15 @@ class TestCommand extends FastFlutterCommand {
               'test cases (must be a 32bit unsigned integer).\n'
               'If "random", pick a random seed to use.\n'
               'If 0 or not set, do not randomize test case execution order.',
+      )
+      ..addFlag('enable-vmservice',
+        defaultsTo: false,
+        hide: !verboseHelp,
+        help: 'Enables the vmservice without --start-paused. This flag is '
+              'intended for use with tests that will use dart:developer to '
+              'interact with the vmservice at runtime.\n'
+              'This flag is ignored if --start-paused or coverage are requested. '
+              'The vmservice will be enabled no matter what in those cases.'
       );
     usesTrackWidgetCreation(verboseHelp: verboseHelp);
   }
@@ -117,6 +127,9 @@ class TestCommand extends FastFlutterCommand {
   /// The interface for starting and configuring the tester.
   final TestWrapper testWrapper;
 
+  /// Interface for running the tester process.
+  final FlutterTestRunner testRunner;
+
   @override
   Future<Set<DevelopmentArtifact>> get requiredArtifacts async {
     final Set<DevelopmentArtifact> results = <DevelopmentArtifact>{};
@@ -235,14 +248,14 @@ class TestCommand extends FastFlutterCommand {
     final bool disableServiceAuthCodes =
       boolArg('disable-service-auth-codes');
 
-    final int result = await runTests(
+    final int result = await testRunner.runTests(
       testWrapper,
       files,
       workDir: workDir,
       names: names,
       plainNames: plainNames,
       watcher: watcher,
-      enableObservatory: collector != null || startPaused,
+      enableObservatory: collector != null || startPaused || boolArg('enable-vmservice'),
       startPaused: startPaused,
       disableServiceAuthCodes: disableServiceAuthCodes,
       ipv6: boolArg('ipv6'),

packages/flutter_tools/lib/src/test/runner.dart

@@ -20,7 +20,42 @@ import 'flutter_web_platform.dart';
 import 'test_wrapper.dart';
 import 'watcher.dart';
 
+/// A class that abstracts launching the test process from the test runner.
+abstract class FlutterTestRunner {
+  const factory FlutterTestRunner() = _FlutterTestRunnerImpl;
+
   /// Runs tests using package:test and the Flutter engine.
+  Future<int> runTests(
+    TestWrapper testWrapper,
+    List<String> testFiles, {
+    Directory workDir,
+    List<String> names = const <String>[],
+    List<String> plainNames = const <String>[],
+    bool enableObservatory = false,
+    bool startPaused = false,
+    bool disableServiceAuthCodes = false,
+    bool ipv6 = false,
+    bool machine = false,
+    String precompiledDillPath,
+    Map<String, String> precompiledDillFiles,
+    @required BuildMode buildMode,
+    bool trackWidgetCreation = false,
+    bool updateGoldens = false,
+    TestWatcher watcher,
+    @required int concurrency,
+    bool buildTestAssets = false,
+    FlutterProject flutterProject,
+    String icudtlPath,
+    Directory coverageDirectory,
+    bool web = false,
+    String randomSeed = '0',
+  });
+}
+
+class _FlutterTestRunnerImpl implements FlutterTestRunner {
+  const _FlutterTestRunnerImpl();
+
+  @override
   Future<int> runTests(
     TestWrapper testWrapper,
     List<String> testFiles, {
@@ -158,3 +193,4 @@ Future<int> runTests(
       await platform.close();
     }
   }
+}

packages/flutter_tools/test/commands.shard/hermetic/test_test.dart

@@ -7,9 +7,13 @@ import 'dart:async';
 import 'package:args/command_runner.dart';
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/build_info.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/commands/test.dart';
+import 'package:flutter_tools/src/project.dart';
+import 'package:flutter_tools/src/test/runner.dart';
 import 'package:flutter_tools/src/test/test_wrapper.dart';
+import 'package:flutter_tools/src/test/watcher.dart';
 import 'package:process/process.dart';
 
 import '../../src/common.dart';
@@ -73,6 +77,92 @@ void main() {
     ProcessManager: () => FakeProcessManager.any(),
     Cache: () => FakeCache(),
   });
+
+  testUsingContext('Pipes enable-observatory', () async {
+    final FakeFlutterTestRunner testRunner = FakeFlutterTestRunner(0);
+
+    final TestCommand testCommand = TestCommand(testRunner: testRunner);
+    final CommandRunner<void> commandRunner =
+        createTestCommandRunner(testCommand);
+
+    await commandRunner.run(const <String>[
+      'test',
+      '--no-pub',
+      '--enable-vmservice',
+      '--',
+      'test/fake_test.dart',
+    ]);
+    expect(
+      testRunner.lastEnableObservatoryValue,
+      true,
+    );
+
+    await commandRunner.run(const <String>[
+      'test',
+      '--no-pub',
+      '--start-paused',
+      '--no-enable-vmservice',
+      '--',
+      'test/fake_test.dart',
+    ]);
+    expect(
+      testRunner.lastEnableObservatoryValue,
+      true,
+    );
+
+    await commandRunner.run(const <String>[
+      'test',
+      '--no-pub',
+      '--',
+      'test/fake_test.dart',
+    ]);
+    expect(
+      testRunner.lastEnableObservatoryValue,
+      false,
+    );
+  }, overrides: <Type, Generator>{
+    FileSystem: () => fs,
+    ProcessManager: () => FakeProcessManager.any(),
+    Cache: () => FakeCache(),
+  });
+}
+
+class FakeFlutterTestRunner implements FlutterTestRunner {
+  FakeFlutterTestRunner(this.exitCode);
+
+  int exitCode;
+  bool lastEnableObservatoryValue;
+
+  @override
+  Future<int> runTests(
+    TestWrapper testWrapper,
+    List<String> testFiles, {
+    Directory workDir,
+    List<String> names = const <String>[],
+    List<String> plainNames = const <String>[],
+    bool enableObservatory = false,
+    bool startPaused = false,
+    bool disableServiceAuthCodes = false,
+    bool ipv6 = false,
+    bool machine = false,
+    String precompiledDillPath,
+    Map<String, String> precompiledDillFiles,
+    BuildMode buildMode,
+    bool trackWidgetCreation = false,
+    bool updateGoldens = false,
+    TestWatcher watcher,
+    int concurrency,
+    bool buildTestAssets = false,
+    FlutterProject flutterProject,
+    String icudtlPath,
+    Directory coverageDirectory,
+    bool web = false,
+    String randomSeed = '0',
+  }) async {
+    lastEnableObservatoryValue = enableObservatory;
+    return exitCode;
+  }
+
 }
 
 class FakePackageTest implements TestWrapper {