Add support for IOS_SIMULATOR_HOME environment variable in IOSSimulat… (#13236)

Add support for IOS_SIMULATOR_HOME environment variable in IOSSimulator.logFilePath

flutter_tools can be run on environments where the user's HOME directory
is not the root of the iOS simulators' configs. This change adds support
for such environments by allowing the caller to set the simulator root
directory via an environment variable.

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

@@ -415,7 +415,9 @@ class IOSSimulator extends Device {
   }
 
   String get logFilePath {
-    return fs.path.join(homeDirPath, 'Library', 'Logs', 'CoreSimulator', id, 'system.log');
+    return platform.environment.containsKey('IOS_SIMULATOR_LOG_FILE_PATH')
+        ? platform.environment['IOS_SIMULATOR_LOG_FILE_PATH'].replaceAll('%{id}', id)
+        : fs.path.join(homeDirPath, 'Library', 'Logs', 'CoreSimulator', id, 'system.log');
   }
 
   @override
@@ -424,6 +426,13 @@ class IOSSimulator extends Device {
   @override
   Future<String> get sdkNameAndVersion async => category;
 
+  final RegExp _iosSdkRegExp = new RegExp(r'iOS (\d+)');
+
+  Future<int> get sdkMajorVersion async {
+    final Match sdkMatch = _iosSdkRegExp.firstMatch(await sdkNameAndVersion);
+    return int.parse(sdkMatch.group(1) ?? 11);
+  }
+
   @override
   DeviceLogReader getLogReader({ApplicationPackage app}) {
     assert(app is IOSApp);
@@ -444,11 +453,13 @@ class IOSSimulator extends Device {
     }
   }
 
-  void ensureLogsExists() {
+  Future<Null> ensureLogsExists() async {
+    if (await sdkMajorVersion < 11) {
       final File logFile = fs.file(logFilePath);
       if (!logFile.existsSync())
         logFile.writeAsBytesSync(<int>[]);
     }
+  }
 
   bool get _xcodeVersionSupportsScreenshot {
     return xcode.xcodeMajorVersion > 8 || (xcode.xcodeMajorVersion == 8 && xcode.xcodeMinorVersion >= 2);
@@ -463,15 +474,10 @@ class IOSSimulator extends Device {
   }
 }
 
-final RegExp _iosSdkRegExp = new RegExp(r'iOS (\d+)');
-
 /// Launches the device log reader process on the host.
 Future<Process> launchDeviceLogTool(IOSSimulator device) async {
-  final Match sdkMatch = _iosSdkRegExp.firstMatch(await device.sdkNameAndVersion);
-  final int majorVersion = int.parse(sdkMatch.group(1) ?? 11);
-
   // Versions of iOS prior to iOS 11 log to the simulator syslog file.
-  if (majorVersion < 11)
+  if (await device.sdkMajorVersion < 11)
     return runCommand(<String>['tail', '-n', '0', '-F', device.logFilePath]);
 
   // For iOS 11 and above, use /usr/bin/log to tail process logs.
@@ -482,11 +488,8 @@ Future<Process> launchDeviceLogTool(IOSSimulator device) async {
 }
 
 Future<Process> launchSystemLogTool(IOSSimulator device) async {
-  final Match sdkMatch = _iosSdkRegExp.firstMatch(await device.sdkNameAndVersion);
-  final int majorVersion = int.parse(sdkMatch.group(1) ?? 11);
-
   // Versions of iOS prior to 11 tail the simulator syslog file.
-  if (majorVersion < 11)
+  if (await device.sdkMajorVersion < 11)
     return runCommand(<String>['tail', '-n', '0', '-F', '/private/var/log/system.log']);
 
   // For iOS 11 and later, all relevant detail is in the device log.
@@ -520,7 +523,7 @@ class _IOSSimulatorLogReader extends DeviceLogReader {
 
   Future<Null> _start() async {
     // Device log.
-    device.ensureLogsExists();
+    await device.ensureLogsExists();
     _deviceProcess = await launchDeviceLogTool(device);
     _deviceProcess.stdout.transform(UTF8.decoder).transform(const LineSplitter()).listen(_onDeviceLine);
     _deviceProcess.stderr.transform(UTF8.decoder).transform(const LineSplitter()).listen(_onDeviceLine);

packages/flutter_tools/test/ios/simulators_test.dart

@@ -18,8 +18,29 @@ class MockProcessManager extends Mock implements ProcessManager {}
 class MockProcess extends Mock implements Process {}
 
 void main() {
-  final FakePlatform osx = new FakePlatform.fromPlatform(const LocalPlatform());
+  FakePlatform osx;
+
+  setUp(() {
+    osx = new FakePlatform.fromPlatform(const LocalPlatform());
     osx.operatingSystem = 'macos';
+  });
+
+  group('logFilePath', () {
+    testUsingContext('defaults to rooted from HOME', () {
+      osx.environment['HOME'] = '/foo/bar';
+      expect(new IOSSimulator('123').logFilePath, '/foo/bar/Library/Logs/CoreSimulator/123/system.log');
+    }, overrides: <Type, Generator>{
+      Platform: () => osx,
+    }, testOn: 'posix');
+
+    testUsingContext('respects IOS_SIMULATOR_LOG_FILE_PATH', () {
+      osx.environment['HOME'] = '/foo/bar';
+      osx.environment['IOS_SIMULATOR_LOG_FILE_PATH'] = '/baz/qux/%{id}/system.log';
+      expect(new IOSSimulator('456').logFilePath, '/baz/qux/456/system.log');
+    }, overrides: <Type, Generator>{
+      Platform: () => osx,
+    });
+  });
 
   group('compareIosVersions', () {
     test('compares correctly', () {

packages/flutter_tools/test/src/context.dart

@@ -68,6 +68,7 @@ void testUsingContext(String description, dynamic testMethod(), {
   Timeout timeout,
   Map<Type, Generator> overrides: const <Type, Generator>{},
   ContextInitializer initializeContext: _defaultInitializeContext,
+  String testOn,
   bool skip, // should default to `false`, but https://github.com/dart-lang/test/issues/545 doesn't allow this
 }) {
 
@@ -124,7 +125,7 @@ void testUsingContext(String description, dynamic testMethod(), {
       rethrow;
     }
 
-  }, timeout: timeout, skip: skip);
+  }, timeout: timeout, testOn: testOn, skip: skip);
 }
 
 void _printBufferedErrors(AppContext testContext) {