Catch crashes during or before coverage collection. (#8207)

This assumes a fix to https://github.com/dart-lang/test/issues/542

The timeout added in this patch is a workaround for https://github.com/dart-lang/coverage/issues/165

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

@@ -193,7 +193,11 @@ class TestCommand extends FlutterCommand {
     final String shellPath = tools.getHostToolPath(HostTool.SkyShell) ?? platform.environment['SKY_SHELL'];
     if (!fs.isFileSync(shellPath))
       throwToolExit('Cannot find Flutter shell at $shellPath');
-    loader.installHook(shellPath: shellPath, collector: collector, debuggerMode: argResults['start-paused']);
+    loader.installHook(
+      shellPath: shellPath,
+      collector: collector,
+      debuggerMode: argResults['start-paused'],
+    );
 
     Cache.releaseLockEarly();
 

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

@@ -4,7 +4,7 @@
 
 import 'dart:async';
 
-import 'package:coverage/coverage.dart';
+import 'package:coverage/coverage.dart' as coverage;
 
 import '../base/file_system.dart';
 import '../base/io.dart';
@@ -19,7 +19,7 @@ class CoverageCollector {
     if (_globalHitmap == null)
       _globalHitmap = hitmap;
     else
-      mergeHitmaps(hitmap, _globalHitmap);
+      coverage.mergeHitmaps(hitmap, _globalHitmap);
   }
 
   /// Collects coverage for the given [Process] using the given `port`.
@@ -37,13 +37,18 @@ class CoverageCollector {
     process.exitCode.then<Null>((int code) {
       exitCode = code;
     });
+    if (exitCode != null)
+      throw new Exception('Failed to collect coverage, process terminated before coverage could be collected.');
 
     printTrace('pid $pid (port $port): collecting coverage data...');
-    final Map<String, dynamic> data = await collect(host.address, port, false, false);
+    final Map<String, dynamic> data = await coverage.collect(host.address, port, false, false).timeout(
+      const Duration(seconds: 30),
+      onTimeout: () { throw new Exception('Failed to collect coverage, it took more than thirty seconds.'); },
+    );
     printTrace('pid $pid (port $port): ${ exitCode != null ? "process terminated prematurely with exit code $exitCode; aborting" : "collected coverage data; merging..." }');
     if (exitCode != null)
-      throw new Exception('Failed to collect coverage, process terminated prematurely.');
-    _addHitmap(createHitmap(data['coverage']));
+      throw new Exception('Failed to collect coverage, process terminated while coverage was being collected.');
+    _addHitmap(coverage.createHitmap(data['coverage']));
     printTrace('pid $pid (port $port): done merging coverage data into global coverage map.');
   }
 
@@ -56,17 +61,17 @@ class CoverageCollector {
   /// If [timeout] is specified, the future will timeout (with a
   /// [TimeoutException]) after the specified duration.
   Future<String> finalizeCoverage({
-    Formatter formatter,
+    coverage.Formatter formatter,
     Duration timeout,
   }) async {
     printTrace('formating coverage data');
     if (_globalHitmap == null)
       return null;
     if (formatter == null) {
-      Resolver resolver = new Resolver(packagesPath: PackageMap.globalPackagesPath);
+      coverage.Resolver resolver = new coverage.Resolver(packagesPath: PackageMap.globalPackagesPath);
       String packagePath = fs.currentDirectory.path;
       List<String> reportOn = <String>[fs.path.join(packagePath, 'lib')];
-      formatter = new LcovFormatter(resolver, reportOn: reportOn, basePath: packagePath);
+      formatter = new coverage.LcovFormatter(resolver, reportOn: reportOn, basePath: packagePath);
     }
     String result = await formatter.format(_globalHitmap);
     _globalHitmap = null;

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

@@ -71,7 +71,13 @@ enum _TestResult { crashed, harnessBailed, testBailed }
 typedef Future<Null> _Finalizer();
 
 class _FlutterPlatform extends PlatformPlugin {
-  _FlutterPlatform({ this.shellPath, this.collector, this.debuggerMode, this.explicitObservatoryPort, this.explicitDiagnosticPort }) {
+  _FlutterPlatform({
+    this.shellPath,
+    this.collector,
+    this.debuggerMode,
+    this.explicitObservatoryPort,
+    this.explicitDiagnosticPort,
+  }) {
     assert(shellPath != null);
   }
 
@@ -113,15 +119,15 @@ class _FlutterPlatform extends PlatformPlugin {
       localController.stream,
       remoteSink,
     );
-    _startTest(testPath, localChannel, ourTestCount).whenComplete(() {
-      testCompleteCompleter.complete();
-    });
+    testCompleteCompleter.complete(_startTest(testPath, localChannel, ourTestCount));
     return remoteChannel;
   }
 
   Future<Null> _startTest(String testPath, StreamChannel<dynamic> controller, int ourTestCount) async {
     printTrace('test $ourTestCount: starting test $testPath');
 
+    dynamic outOfBandError; // error that we couldn't send to the harness that we need to send via our future
+
     final List<_Finalizer> finalizers = <_Finalizer>[];
     bool subprocessActive = false;
     bool controllerSinkClosed = false;
@@ -334,6 +340,7 @@ class _FlutterPlatform extends PlatformPlugin {
         controller.sink.addError(error, stack);
       } else {
         printError('unhandled error during test:\n$testPath\n$error');
+        outOfBandError ??= error;
       }
     } finally {
       printTrace('test $ourTestCount: cleaning up...');
@@ -346,6 +353,7 @@ class _FlutterPlatform extends PlatformPlugin {
             controller.sink.addError(error, stack);
           } else {
             printError('unhandled error during finalization of test:\n$testPath\n$error');
+            outOfBandError ??= error;
           }
         }
       }
@@ -357,6 +365,10 @@ class _FlutterPlatform extends PlatformPlugin {
     }
     assert(!subprocessActive);
     assert(controllerSinkClosed);
+    if (outOfBandError != null) {
+      printTrace('test $ourTestCount: finished with out-of-band failure');
+      throw outOfBandError;
+    }
     printTrace('test $ourTestCount: finished');
     return null;
   }