Create abstraction layer for dart:io's Process commands (#7100)

With this change, they're run via instance methods on an object
obtained through the context. This will allow us to substitute
that object in tests with replay/record versions to allow us to
mock out the os-layer in tests.

packages/flutter_tools/lib/executable.dart

@@ -14,6 +14,7 @@ import 'src/base/context.dart';
 import 'src/base/logger.dart';
 import 'src/base/os.dart';
 import 'src/base/process.dart';
+import 'src/base/process_manager.dart';
 import 'src/base/utils.dart';
 import 'src/cache.dart';
 import 'src/commands/analyze.dart';
@@ -95,7 +96,11 @@ Future<Null> main(List<String> args) async {
   // Make the context current.
   _executableContext.runInZone(() {
     // Initialize the context with some defaults.
+    // Seed these context entries first since others depend on them
+    context.putIfAbsent(ProcessManager, () => new ProcessManager());
     context.putIfAbsent(Logger, () => new StdoutLogger());
+
+    // Order-independent context entries
     context.putIfAbsent(DeviceManager, () => new DeviceManager());
     context.putIfAbsent(DevFSConfig, () => new DevFSConfig());
     context.putIfAbsent(Doctor, () => new Doctor());

packages/flutter_tools/lib/src/android/android_device.dart

@@ -11,6 +11,7 @@ import '../application_package.dart';
 import '../base/os.dart';
 import '../base/logger.dart';
 import '../base/process.dart';
+import '../base/process_manager.dart';
 import '../build_info.dart';
 import '../commands/build_apk.dart';
 import '../device.dart';
@@ -59,7 +60,7 @@ class AndroidDevice extends Device {
       try {
         // We pass an encoding of LATIN1 so that we don't try and interpret the
         // `adb shell getprop` result as UTF8.
-        ProcessResult result = Process.runSync(
+        ProcessResult result = processManager.runSync(
           propCommand.first,
           propCommand.sublist(1),
           stdoutEncoding: LATIN1

packages/flutter_tools/lib/src/android/android_workflow.dart

@@ -6,6 +6,7 @@ import 'dart:async';
 import 'dart:io';
 
 import '../base/os.dart';
+import '../base/process_manager.dart';
 import '../doctor.dart';
 import '../globals.dart';
 import 'android_sdk.dart';
@@ -70,7 +71,7 @@ class AndroidWorkflow extends DoctorValidator implements Workflow {
         try {
           printTrace('java -version');
 
-          ProcessResult result = Process.runSync('java', <String>['-version']);
+          ProcessResult result = processManager.runSync('java', <String>['-version']);
           if (result.exitCode == 0) {
             javaVersion = result.stderr;
             List<String> versionLines = javaVersion.split('\n');

packages/flutter_tools/lib/src/base/os.dart

@@ -10,6 +10,7 @@ import 'package:path/path.dart' as path;
 
 import 'context.dart';
 import 'process.dart';
+import 'process_manager.dart';
 
 /// Returns [OperatingSystemUtils] active in the current app context (i.e. zone).
 OperatingSystemUtils get os => context[OperatingSystemUtils];
@@ -49,14 +50,14 @@ class _PosixUtils extends OperatingSystemUtils {
 
   @override
   ProcessResult makeExecutable(File file) {
-    return Process.runSync('chmod', <String>['a+x', file.path]);
+    return processManager.runSync('chmod', <String>['a+x', file.path]);
   }
 
   /// Return the path to the given executable, or `null` if `which` was not able
   /// to locate the binary.
   @override
   File which(String execName) {
-    ProcessResult result = Process.runSync('which', <String>[execName]);
+    ProcessResult result = processManager.runSync('which', <String>[execName]);
     if (result.exitCode != 0)
       return null;
     String path = result.stdout.trim().split('\n').first.trim();
@@ -87,7 +88,7 @@ class _WindowsUtils extends OperatingSystemUtils {
 
   @override
   File which(String execName) {
-    ProcessResult result = Process.runSync('where', <String>[execName]);
+    ProcessResult result = processManager.runSync('where', <String>[execName]);
     if (result.exitCode != 0)
       return null;
     return new File(result.stdout.trim().split('\n').first.trim());

packages/flutter_tools/lib/src/base/process.dart

@@ -6,6 +6,7 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
+import 'process_manager.dart';
 import '../globals.dart';
 
 typedef String StringConverter(String string);
@@ -44,7 +45,7 @@ Future<Process> runCommand(List<String> cmd, {
   _traceCommand(cmd, workingDirectory: workingDirectory);
   String executable = cmd[0];
   List<String> arguments = cmd.length > 1 ? cmd.sublist(1) : <String>[];
-  Process process = await Process.start(
+  Process process = await processManager.start(
     executable,
     arguments,
     workingDirectory: workingDirectory,
@@ -108,13 +109,13 @@ Future<Null> runAndKill(List<String> cmd, Duration timeout) {
   Future<Process> proc = runDetached(cmd);
   return new Future<Null>.delayed(timeout, () async {
     printTrace('Intentionally killing ${cmd[0]}');
-    Process.killPid((await proc).pid);
+    processManager.killPid((await proc).pid);
   });
 }
 
 Future<Process> runDetached(List<String> cmd) {
   _traceCommand(cmd);
-  Future<Process> proc = Process.start(
+  Future<Process> proc = processManager.start(
     cmd[0], cmd.getRange(1, cmd.length).toList(),
     mode: ProcessStartMode.DETACHED
   );
@@ -126,7 +127,7 @@ Future<RunResult> runAsync(List<String> cmd, {
   bool allowReentrantFlutter: false
 }) async {
   _traceCommand(cmd, workingDirectory: workingDirectory);
-  ProcessResult results = await Process.run(
+  ProcessResult results = await processManager.run(
     cmd[0],
     cmd.getRange(1, cmd.length).toList(),
     workingDirectory: workingDirectory,
@@ -140,7 +141,7 @@ Future<RunResult> runAsync(List<String> cmd, {
 bool exitsHappy(List<String> cli) {
   _traceCommand(cli);
   try {
-    return Process.runSync(cli.first, cli.sublist(1)).exitCode == 0;
+    return processManager.runSync(cli.first, cli.sublist(1)).exitCode == 0;
   } catch (error) {
     return false;
   }
@@ -203,7 +204,7 @@ String _runWithLoggingSync(List<String> cmd, {
   bool hideStdout: false,
 }) {
   _traceCommand(cmd, workingDirectory: workingDirectory);
-  ProcessResult results = Process.runSync(
+  ProcessResult results = processManager.runSync(
     cmd[0],
     cmd.getRange(1, cmd.length).toList(),
     workingDirectory: workingDirectory,

packages/flutter_tools/lib/src/base/process_manager.dart

+// Copyright 2016 The Chromium Authors. 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 'context.dart';
+
+ProcessManager get processManager => context[ProcessManager];
+
+class ProcessManager {
+  Future<Process> start(
+      String executable,
+      List<String> arguments,
+      {String workingDirectory,
+       Map<String, String> environment,
+       ProcessStartMode mode: ProcessStartMode.NORMAL}) {
+    return Process.start(
+      executable,
+      arguments,
+      workingDirectory: workingDirectory,
+      environment: environment,
+      mode: mode,
+    );
+  }
+
+  Future<ProcessResult> run(
+      String executable,
+      List<String> arguments,
+      {String workingDirectory,
+       Map<String, String> environment,
+       Encoding stdoutEncoding: SYSTEM_ENCODING,
+       Encoding stderrEncoding: SYSTEM_ENCODING}) {
+    return Process.run(
+      executable,
+      arguments,
+      workingDirectory: workingDirectory,
+      environment: environment,
+      stdoutEncoding: stdoutEncoding,
+      stderrEncoding: stderrEncoding,
+    );
+  }
+
+  ProcessResult runSync(
+      String executable,
+      List<String> arguments,
+      {String workingDirectory,
+       Map<String, String> environment,
+       Encoding stdoutEncoding: SYSTEM_ENCODING,
+       Encoding stderrEncoding: SYSTEM_ENCODING}) {
+    return Process.runSync(
+      executable,
+      arguments,
+      workingDirectory: workingDirectory,
+      environment: environment,
+      stdoutEncoding: stdoutEncoding,
+      stderrEncoding: stderrEncoding,
+    );
+  }
+
+  bool killPid(int pid, [ProcessSignal signal = ProcessSignal.SIGTERM]) {
+    return Process.killPid(pid, signal);
+  }
+}

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

@@ -11,6 +11,7 @@ import 'package:path/path.dart' as path;
 
 import '../base/common.dart';
 import '../base/logger.dart';
+import '../base/process_manager.dart';
 import '../base/utils.dart';
 import '../cache.dart';
 import '../dart/sdk.dart';
@@ -159,7 +160,7 @@ class AnalysisServer {
     List<String> args = <String>[snapshot, '--sdk', sdk];
 
     printTrace('dart ${args.join(' ')}');
-    _process = await Process.start(path.join(dartSdkPath, 'bin', 'dart'), args);
+    _process = await processManager.start(path.join(dartSdkPath, 'bin', 'dart'), args);
     _process.exitCode.whenComplete(() => _process = null);
 
     Stream<String> errorStream = _process.stderr.transform(UTF8.decoder).transform(const LineSplitter());

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

@@ -10,6 +10,7 @@ import 'package:test/src/executable.dart' as executable; // ignore: implementati
 
 import '../base/common.dart';
 import '../base/logger.dart';
+import '../base/process_manager.dart';
 import '../base/os.dart';
 import '../cache.dart';
 import '../dart/package_map.dart';
@@ -126,7 +127,7 @@ class TestCommand extends FlutterCommand {
       Directory tempDir = Directory.systemTemp.createTempSync('flutter_tools');
       try {
         File sourceFile = coverageFile.copySync(path.join(tempDir.path, 'lcov.source.info'));
-        ProcessResult result = Process.runSync('lcov', <String>[
+        ProcessResult result = processManager.runSync('lcov', <String>[
           '--add-tracefile', baseCoverageData,
           '--add-tracefile', sourceFile.path,
           '--output-file', coverageFile.path,

packages/flutter_tools/lib/src/ios/devices.dart

@@ -9,6 +9,7 @@ import 'dart:io';
 import '../application_package.dart';
 import '../base/os.dart';
 import '../base/process.dart';
+import '../base/process_manager.dart';
 import '../build_info.dart';
 import '../device.dart';
 import '../doctor.dart';
@@ -514,7 +515,7 @@ class _IOSDevicePortForwarder extends DevicePortForwarder {
     Process process = forwardedPort.context;
 
     if (process != null) {
-      Process.killPid(process.pid);
+      processManager.killPid(process.pid);
     } else {
       printError("Forwarded port did not have a valid process");
     }

packages/flutter_tools/lib/src/ios/mac.dart

@@ -11,6 +11,7 @@ import 'package:path/path.dart' as path;
 import '../application_package.dart';
 import '../base/context.dart';
 import '../base/process.dart';
+import '../base/process_manager.dart';
 import '../build_info.dart';
 import '../flx.dart' as flx;
 import '../globals.dart';
@@ -39,7 +40,7 @@ class XCode {
       } else {
         try {
           printTrace('xcrun clang');
-          ProcessResult result = Process.runSync('/usr/bin/xcrun', <String>['clang']);
+          ProcessResult result = processManager.runSync('/usr/bin/xcrun', <String>['clang']);
 
           if (result.stdout != null && result.stdout.contains('license'))
             _eulaSigned = false;

packages/flutter_tools/lib/src/ios/simulators.dart

@@ -13,6 +13,7 @@ import '../application_package.dart';
 import '../base/common.dart';
 import '../base/context.dart';
 import '../base/process.dart';
+import '../base/process_manager.dart';
 import '../build_info.dart';
 import '../device.dart';
 import '../flx.dart' as flx;
@@ -190,7 +191,7 @@ class SimControl {
 
     List<String> args = <String>['simctl', 'list', '--json', section.name];
     printTrace('$_xcrunPath ${args.join(' ')}');
-    ProcessResult results = Process.runSync(_xcrunPath, args);
+    ProcessResult results = processManager.runSync(_xcrunPath, args);
     if (results.exitCode != 0) {
       printError('Error executing simctl: ${results.exitCode}\n${results.stderr}');
       return <String, Map<String, dynamic>>{};

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

@@ -15,6 +15,7 @@ import 'package:test/src/backend/test_platform.dart'; // ignore: implementation_
 import 'package:test/src/runner/plugin/platform.dart'; // ignore: implementation_imports
 import 'package:test/src/runner/plugin/hack_register_platform.dart' as hack; // ignore: implementation_imports
 
+import '../base/process_manager.dart';
 import '../dart/package_map.dart';
 import '../globals.dart';
 import 'coverage_collector.dart';
@@ -74,7 +75,7 @@ Future<Process> _startProcess(String mainPath, { String packages, int observator
     'FLUTTER_TEST': 'true',
     'FONTCONFIG_FILE': _fontConfigFile.path,
   };
-  return Process.start(executable, arguments, environment: environment);
+  return processManager.start(executable, arguments, environment: environment);
 }
 
 void _attachStandardStreams(Process process) {

packages/flutter_tools/lib/src/version.dart

@@ -5,6 +5,7 @@
 import 'dart:io';
 
 import 'base/process.dart';
+import 'base/process_manager.dart';
 import 'cache.dart';
 
 final Set<String> kKnownBranchNames = new Set<String>.from(<String>[
@@ -102,7 +103,7 @@ class FlutterVersion {
 }
 
 String _runSync(String executable, List<String> arguments, String cwd) {
-  ProcessResult results = Process.runSync(executable, arguments, workingDirectory: cwd);
+  ProcessResult results = processManager.runSync(executable, arguments, workingDirectory: cwd);
   return results.exitCode == 0 ? results.stdout.trim() : '';
 }
 

packages/flutter_tools/test/analytics_test.dart

@@ -49,8 +49,8 @@ void main() {
       runner = createTestCommandRunner(doctorCommand);
       await runner.run(<String>['doctor']);
       expect(count, 0);
-    }, overrides: <Type, dynamic>{
-      Usage: new Usage()
+    }, overrides: <Type, Generator>{
+      Usage: () => new Usage(),
     });
 
     // Ensure we con't send for the 'flutter config' command.
@@ -67,8 +67,8 @@ void main() {
       flutterUsage.enabled = true;
       await runner.run(<String>['config']);
       expect(count, 0);
-    }, overrides: <Type, dynamic>{
-      Usage: new Usage()
+    }, overrides: <Type, Generator>{
+      Usage: () => new Usage(),
     });
   });
 
@@ -79,8 +79,11 @@ void main() {
 
       await createTestCommandRunner().run(<String>['--version']);
       expect(count, 0);
-    }, overrides: <Type, dynamic>{
-      Usage: new Usage(settingsName: 'flutter_bot_test', versionOverride: 'dev/unknown')
+    }, overrides: <Type, Generator>{
+      Usage: () => new Usage(
+        settingsName: 'flutter_bot_test',
+        versionOverride: 'dev/unknown',
+      ),
     });
   });
 }

packages/flutter_tools/test/analyze_continuously_test.dart

@@ -45,8 +45,8 @@ void main() {
       await onDone;
 
       expect(errorCount, 0);
-    }, overrides: <Type, dynamic>{
-      OperatingSystemUtils: os
+    }, overrides: <Type, Generator>{
+      OperatingSystemUtils: () => os
     });
   });
 
@@ -65,8 +65,8 @@ void main() {
     await onDone;
 
     expect(errorCount, 2);
-  }, overrides: <Type, dynamic>{
-    OperatingSystemUtils: os
+  }, overrides: <Type, Generator>{
+    OperatingSystemUtils: () => os
   });
 }
 

packages/flutter_tools/test/devices_test.dart

@@ -21,9 +21,9 @@ void main() {
       DevicesCommand command = new DevicesCommand();
       await createTestCommandRunner(command).run(<String>['devices']);
       expect(testLogger.statusText, contains('No devices detected'));
-    }, overrides: <Type, dynamic>{
-      AndroidSdk: null,
-      DeviceManager: new DeviceManager()
+    }, overrides: <Type, Generator>{
+      AndroidSdk: () => null,
+      DeviceManager: () => new DeviceManager(),
     });
   });
 }

packages/flutter_tools/test/os_utils_test.dart

@@ -33,8 +33,8 @@ void main() {
         // rwxr--r--
         expect(mode.substring(0, 3), endsWith('x'));
       }
-    }, overrides: <Type, dynamic> {
-      OperatingSystemUtils: new OperatingSystemUtils(),
+    }, overrides: <Type, Generator> {
+      OperatingSystemUtils: () => new OperatingSystemUtils(),
     });
   });
 }

packages/flutter_tools/test/src/context.dart

@@ -8,6 +8,7 @@ import 'package:flutter_tools/src/base/config.dart';
 import 'package:flutter_tools/src/base/context.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/os.dart';
+import 'package:flutter_tools/src/base/process_manager.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/device.dart';
 import 'package:flutter_tools/src/devfs.dart';
@@ -27,20 +28,21 @@ BufferLogger get testLogger => context[Logger];
 MockDeviceManager get testDeviceManager => context[DeviceManager];
 MockDoctor get testDoctor => context[Doctor];
 
+typedef dynamic Generator();
+
 void testUsingContext(String description, dynamic testMethod(), {
   Timeout timeout,
-  Map<Type, dynamic> overrides: const <Type, dynamic>{}
+  Map<Type, Generator> overrides: const <Type, Generator>{}
 }) {
   test(description, () async {
     AppContext testContext = new AppContext();
 
-    // Apply all overrides to the test context.
-    overrides.forEach((Type type, dynamic value) {
-      testContext.setVariable(type, value);
-    });
-
     // Initialize the test context with some default mocks.
+    // Seed these context entries first since others depend on them
+    testContext.putIfAbsent(ProcessManager, () => new ProcessManager());
     testContext.putIfAbsent(Logger, () => new BufferLogger());
+
+    // Order-independent context entries
     testContext.putIfAbsent(DeviceManager, () => new MockDeviceManager());
     testContext.putIfAbsent(DevFSConfig, () => new DevFSConfig());
     testContext.putIfAbsent(Doctor, () => new MockDoctor());
@@ -63,7 +65,15 @@ void testUsingContext(String description, dynamic testMethod(), {
     testContext.putIfAbsent(Usage, () => new MockUsage());
 
     try {
-      return await testContext.runInZone(testMethod);
+      return await testContext.runInZone(() {
+        // Apply the overrides to the test context in the zone since their
+        // instantiation may reference items already stored on the context.
+        overrides.forEach((Type type, dynamic value()) {
+          context.setVariable(type, value());
+        });
+
+        return testMethod();
+      });
     } catch (error) {
       if (testContext[Logger] is BufferLogger) {
         BufferLogger bufferLogger = testContext[Logger];

packages/flutter_tools/test/toolchain_test.dart

@@ -29,8 +29,8 @@ void main() {
       );
       expect(tempDir, isNotNull);
       tempDir.deleteSync(recursive: true);
-    }, overrides: <Type, dynamic> {
-      Cache: new Cache(rootOverride: tempDir)
+    }, overrides: <Type, Generator> {
+      Cache: () => new Cache(rootOverride: tempDir),
     });
 
     testUsingContext('using enginePath', () {