Add coverage directory to fuchsia coverage script (#22236)

packages/flutter_tools/bin/fuchsia_tester.dart

@@ -30,6 +30,7 @@ const String _kOptionTestDirectory = 'test-directory';
 const String _kOptionSdkRoot = 'sdk-root';
 const String _kOptionIcudtl = 'icudtl';
 const String _kOptionTests = 'tests';
+const String _kOptionCoverageDirectory = 'coverage-directory';
 const List<String> _kRequiredOptions = <String>[
   _kOptionPackages,
   _kOptionShell,
@@ -55,6 +56,7 @@ Future<Null> run(List<String> args) async {
     ..addOption(_kOptionSdkRoot, help: 'Path to the SDK platform files')
     ..addOption(_kOptionIcudtl, help: 'Path to the ICU data file')
     ..addOption(_kOptionTests, help: 'Path to json file that maps Dart test files to precompiled dill files')
+    ..addOption(_kOptionCoverageDirectory, help: 'The path to the directory that will have coverage collected')
     ..addFlag(_kOptionCoverage,
       defaultsTo: false,
       negatable: false,
@@ -85,6 +87,14 @@ Future<Null> run(List<String> args) async {
     if (!fs.isDirectorySync(sdkRootSrc.path)) {
       throwToolExit('Cannot find SDK files at ${sdkRootSrc.path}');
     }
+    Directory coverageDirectory;
+    final String coverageDirectoryPath = argResults[_kOptionCoverageDirectory];
+    if (coverageDirectoryPath != null) {
+      if (!fs.isDirectorySync(coverageDirectoryPath)) {
+        throwToolExit('Cannot find coverage directory at $coverageDirectoryPath');
+      }
+      coverageDirectory = fs.directory(coverageDirectoryPath);
+    }
 
     // Put the tester shell where runTests expects it.
     // TODO(tvolkert,garymm): Switch to a Fuchsia-specific Artifacts impl.
@@ -131,9 +141,14 @@ Future<Null> run(List<String> args) async {
 
     if (collector != null) {
       // collector expects currentDirectory to be the root of the dart
-      // package (i.e. contains lib/ and test/ sub-dirs).
+      // package (i.e. contains lib/ and test/ sub-dirs). In some cases,
+      // test files may appear to be in the root directory.
+      if (coverageDirectory == null) {
         fs.currentDirectory = testDirectory.parent;
-      if (!await collector.collectCoverageData(argResults[_kOptionCoveragePath]))
+      } else {
+        fs.currentDirectory = testDirectory;
+      }
+      if (!await collector.collectCoverageData(argResults[_kOptionCoveragePath], coverageDirectory: coverageDirectory))
         throwToolExit('Failed to collect coverage data');
     }
   } finally {

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

@@ -83,6 +83,7 @@ class CoverageCollector extends TestWatcher {
   Future<String> finalizeCoverage({
     coverage.Formatter formatter,
     Duration timeout,
+    Directory coverageDirectory,
   }) async {
     printTrace('formating coverage data');
     if (_globalHitmap == null)
@@ -90,7 +91,9 @@ class CoverageCollector extends TestWatcher {
     if (formatter == null) {
       final coverage.Resolver resolver = coverage.Resolver(packagesPath: PackageMap.globalPackagesPath);
       final String packagePath = fs.currentDirectory.path;
-      final List<String> reportOn = <String>[fs.path.join(packagePath, 'lib')];
+      final List<String> reportOn = coverageDirectory == null
+        ? <String>[fs.path.join(packagePath, 'lib')]
+        : <String>[coverageDirectory.path];
       formatter = coverage.LcovFormatter(resolver, reportOn: reportOn, basePath: packagePath);
     }
     final String result = await formatter.format(_globalHitmap);
@@ -98,10 +101,11 @@ class CoverageCollector extends TestWatcher {
     return result;
   }
 
-  Future<bool> collectCoverageData(String coveragePath, { bool mergeCoverageData = false }) async {
+  Future<bool> collectCoverageData(String coveragePath, { bool mergeCoverageData = false, Directory coverageDirectory }) async {
     final Status status = logger.startProgress('Collecting coverage information...');
     final String coverageData = await finalizeCoverage(
       timeout: const Duration(seconds: 30),
+      coverageDirectory: coverageDirectory,
     );
     status.stop();
     printTrace('coverage information collection complete');