packages/flutter_tools/lib/src/test/coverage_collector.dart - external/github.com/flutter/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 // @dart = 2.8

 import 'package:coverage/coverage.dart' as coverage;
 import 'package:meta/meta.dart';
 import 'package:vm_service/vm_service.dart' as vm_service;

 import '../base/file_system.dart';
 import '../base/io.dart';
 import '../base/process.dart';
 import '../globals_null_migrated.dart' as globals;
 import '../vmservice.dart';

 import 'test_device.dart';
 import 'watcher.dart';

 /// A class that's used to collect coverage data during tests.
 class CoverageCollector extends TestWatcher {
   CoverageCollector({this.libraryPredicate, this.verbose = true, @required this.packagesPath});

   final bool verbose;
   final String packagesPath;
   Map<String, Map<int, int>> _globalHitmap;
   bool Function(String) libraryPredicate;

   @override
   Future<void> handleFinishedTest(TestDevice testDevice) async {
     _logMessage('Starting coverage collection');
     await collectCoverage(testDevice);
   }

   void _logMessage(String line, { bool error = false }) {
     if (!verbose) {
       return;
     }
     if (error) {
       globals.printError(line);
     } else {
       globals.printTrace(line);
     }
   }

   void _addHitmap(Map<String, Map<int, int>> hitmap) {
     if (_globalHitmap == null) {
       _globalHitmap = hitmap;
     } else {
       coverage.mergeHitmaps(hitmap, _globalHitmap);
     }
   }

   /// Collects coverage for an isolate using the given `port`.
   ///
   /// This should be called when the code whose coverage data is being collected
   /// has been run to completion so that all coverage data has been recorded.
   ///
   /// The returned [Future] completes when the coverage is collected.
   Future<void> collectCoverageIsolate(Uri observatoryUri) async {
     assert(observatoryUri != null);
     _logMessage('collecting coverage data from $observatoryUri...');
     final Map<String, dynamic> data = await collect(observatoryUri, libraryPredicate);
     if (data == null) {
       throw Exception('Failed to collect coverage.');
     }
     assert(data != null);

     _logMessage('($observatoryUri): collected coverage data; merging...');
     _addHitmap(await coverage.createHitmap(
       data['coverage'] as List<Map<String, dynamic>>,
       packagesPath: packagesPath,
       checkIgnoredLines: true,
     ));
     _logMessage('($observatoryUri): done merging coverage data into global coverage map.');
   }

   /// Collects coverage for the given [Process] using the given `port`.
   ///
   /// This should be called when the code whose coverage data is being collected
   /// has been run to completion so that all coverage data has been recorded.
   ///
   /// The returned [Future] completes when the coverage is collected.
   Future<void> collectCoverage(TestDevice testDevice) async {
     assert(testDevice != null);

     Map<String, dynamic> data;

     final Future<void> processComplete = testDevice.finished.catchError(
       (Object error) => throw Exception(
           'Failed to collect coverage, test device terminated prematurely with '
           'error: ${(error as TestDeviceException).message}.'),
       test: (Object error) => error is TestDeviceException,
     );

     final Future<void> collectionComplete = testDevice.observatoryUri
       .then((Uri observatoryUri) {
         _logMessage('collecting coverage data from $testDevice at $observatoryUri...');
         return collect(observatoryUri, libraryPredicate)
           .then<void>((Map<String, dynamic> result) {
             if (result == null) {
               throw Exception('Failed to collect coverage.');
             }
             _logMessage('Collected coverage data.');
             data = result;
           });
       });

     await Future.any<void>(<Future<void>>[ processComplete, collectionComplete ]);
     assert(data != null);

     _logMessage('Merging coverage data...');
     _addHitmap(await coverage.createHitmap(
       data['coverage'] as List<Map<String, dynamic>>,
       packagesPath: packagesPath,
       checkIgnoredLines: true,
     ));
     _logMessage('Done merging coverage data into global coverage map.');
   }

   /// Returns a future that will complete with the formatted coverage data
   /// (using [formatter]) once all coverage data has been collected.
   ///
   /// This will not start any collection tasks. It us up to the caller of to
   /// call [collectCoverage] for each process first.
   Future<String> finalizeCoverage({
     coverage.Formatter formatter,
     Directory coverageDirectory,
   }) async {
     if (_globalHitmap == null) {
       return null;
     }
     if (formatter == null) {
       final coverage.Resolver resolver = coverage.Resolver(packagesPath: packagesPath);
       final String packagePath = globals.fs.currentDirectory.path;
       final List<String> reportOn = coverageDirectory == null
         ? <String>[globals.fs.path.join(packagePath, 'lib')]
         : <String>[coverageDirectory.path];
       formatter = coverage.LcovFormatter(resolver, reportOn: reportOn, basePath: packagePath);
     }
     final String result = await formatter.format(_globalHitmap);
     _globalHitmap = null;
     return result;
   }

   Future<bool> collectCoverageData(String coveragePath, { bool mergeCoverageData = false, Directory coverageDirectory }) async {
     final String coverageData = await finalizeCoverage(
       coverageDirectory: coverageDirectory,
     );
     _logMessage('coverage information collection complete');
     if (coverageData == null) {
       return false;
     }

     final File coverageFile = globals.fs.file(coveragePath)
       ..createSync(recursive: true)
       ..writeAsStringSync(coverageData, flush: true);
     _logMessage('wrote coverage data to $coveragePath (size=${coverageData.length})');

     const String baseCoverageData = 'coverage/lcov.base.info';
     if (mergeCoverageData) {
       if (!globals.fs.isFileSync(baseCoverageData)) {
         _logMessage('Missing "$baseCoverageData". Unable to merge coverage data.', error: true);
         return false;
       }

       if (globals.os.which('lcov') == null) {
         String installMessage = 'Please install lcov.';
         if (globals.platform.isLinux) {
           installMessage = 'Consider running "sudo apt-get install lcov".';
         } else if (globals.platform.isMacOS) {
           installMessage = 'Consider running "brew install lcov".';
         }
         _logMessage('Missing "lcov" tool. Unable to merge coverage data.\n$installMessage', error: true);
         return false;
       }

       final Directory tempDir = globals.fs.systemTempDirectory.createTempSync('flutter_tools_test_coverage.');
       try {
         final File sourceFile = coverageFile.copySync(globals.fs.path.join(tempDir.path, 'lcov.source.info'));
         final RunResult result = globals.processUtils.runSync(<String>[
           'lcov',
           '--add-tracefile', baseCoverageData,
           '--add-tracefile', sourceFile.path,
           '--output-file', coverageFile.path,
         ]);
         if (result.exitCode != 0) {
           return false;
         }
       } finally {
         tempDir.deleteSync(recursive: true);
       }
     }
     return true;
   }

   @override
   Future<void> handleTestCrashed(TestDevice testDevice) async { }

   @override
   Future<void> handleTestTimedOut(TestDevice testDevice) async { }
 }

 Future<FlutterVmService> _defaultConnect(Uri serviceUri) {
   return connectToVmService(
       serviceUri, compression: CompressionOptions.compressionOff, logger: globals.logger,);
 }

 Future<Map<String, dynamic>> collect(Uri serviceUri, bool Function(String) libraryPredicate, {
   bool waitPaused = false,
   String debugName,
   Future<FlutterVmService> Function(Uri) connector = _defaultConnect,
   @visibleForTesting bool forceSequential = false,
 }) async {
   final FlutterVmService vmService = await connector(serviceUri);
   final Map<String, dynamic> result = await _getAllCoverage(vmService.service, libraryPredicate, forceSequential);
   await vmService.dispose();
   return result;
 }

 Future<Map<String, dynamic>> _getAllCoverage(
   vm_service.VmService service,
   bool Function(String) libraryPredicate,
   bool forceSequential,
 ) async {
   final vm_service.Version version = await service.getVersion();
   final bool reportLines = (version.major == 3 && version.minor >= 51) || version.major > 3;
   final vm_service.VM vm = await service.getVM();
   final List<Map<String, dynamic>> coverage = <Map<String, dynamic>>[];
   for (final vm_service.IsolateRef isolateRef in vm.isolates) {
     if (isolateRef.isSystemIsolate) {
       continue;
     }
     vm_service.ScriptList scriptList;
     try {
       scriptList = await service.getScripts(isolateRef.id);
     } on vm_service.SentinelException {
       continue;
     }

     final List<Future<void>> futures = <Future<void>>[];
     final Map<String, vm_service.Script> scripts = <String, vm_service.Script>{};
     final Map<String, vm_service.SourceReport> sourceReports = <String, vm_service.SourceReport>{};
     // For each ScriptRef loaded into the VM, load the corresponding Script and
     // SourceReport object.

     for (final vm_service.ScriptRef script in scriptList.scripts) {
       final String libraryUri = script.uri;
       if (!libraryPredicate(libraryUri)) {
         continue;
       }
       final String scriptId = script.id;
       final Future<void> getSourceReport = service.getSourceReport(
         isolateRef.id,
         <String>['Coverage'],
         scriptId: scriptId,
         forceCompile: true,
         reportLines: reportLines ? true : null,
       )
       .then((vm_service.SourceReport report) {
         sourceReports[scriptId] = report;
       });
       if (forceSequential) {
         await null;
       }
       futures.add(getSourceReport);
       if (reportLines) {
         continue;
       }
       final Future<void> getObject = service
         .getObject(isolateRef.id, scriptId)
         .then((vm_service.Obj response) {
           final vm_service.Script script = response as vm_service.Script;
           scripts[scriptId] = script;
         });
       futures.add(getObject);
     }
     await Future.wait(futures);
     _buildCoverageMap(scripts, sourceReports, coverage, reportLines);
   }
   return <String, dynamic>{'type': 'CodeCoverage', 'coverage': coverage};
 }

 // Build a hitmap of Uri -> Line -> Hit Count for each script object.
 void _buildCoverageMap(
   Map<String, vm_service.Script> scripts,
   Map<String, vm_service.SourceReport> sourceReports,
   List<Map<String, dynamic>> coverage,
   bool reportLines,
 ) {
   final Map<String, Map<int, int>> hitMaps = <String, Map<int, int>>{};
   for (final String scriptId in sourceReports.keys) {
     final vm_service.SourceReport sourceReport = sourceReports[scriptId];
     for (final vm_service.SourceReportRange range in sourceReport.ranges) {
       final vm_service.SourceReportCoverage coverage = range.coverage;
       // Coverage reports may sometimes be null for a Script.
       if (coverage == null) {
         continue;
       }
       final vm_service.ScriptRef scriptRef = sourceReport.scripts[range.scriptIndex];
       final String uri = scriptRef.uri;

       hitMaps[uri] ??= <int, int>{};
       final Map<int, int> hitMap = hitMaps[uri];
       final List<int> hits = coverage.hits;
       final List<int> misses = coverage.misses;
       final List<dynamic> tokenPositions = scripts[scriptRef.id]?.tokenPosTable;
       // The token positions can be null if the script has no lines that may be
       // covered. It will also be null if reportLines is true.
       if (tokenPositions == null && !reportLines) {
         continue;
       }
       if (hits != null) {
         for (final int hit in hits) {
           final int line =
               reportLines ? hit : _lineAndColumn(hit, tokenPositions)[0];
           final int current = hitMap[line] ?? 0;
           hitMap[line] = current + 1;
         }
       }
       if (misses != null) {
         for (final int miss in misses) {
           final int line =
               reportLines ? miss : _lineAndColumn(miss, tokenPositions)[0];
           hitMap[line] ??= 0;
         }
       }
     }
   }
   hitMaps.forEach((String uri, Map<int, int> hitMap) {
     coverage.add(_toScriptCoverageJson(uri, hitMap));
   });
 }

 // Binary search the token position table for the line and column which
 // corresponds to each token position.
 // The format of this table is described in https://github.com/dart-lang/sdk/blob/main/runtime/vm/service/service.md#script
 List<int> _lineAndColumn(int position, List<dynamic> tokenPositions) {
   int min = 0;
   int max = tokenPositions.length;
   while (min < max) {
     final int mid = min + ((max - min) >> 1);
     final List<int> row = (tokenPositions[mid] as List<dynamic>).cast<int>();
     if (row[1] > position) {
       max = mid;
     } else {
       for (int i = 1; i < row.length; i += 2) {
         if (row[i] == position) {
           return <int>[row.first, row[i + 1]];
         }
       }
       min = mid + 1;
     }
   }
   throw StateError('Unreachable');
 }

 // Returns a JSON hit map backward-compatible with pre-1.16.0 SDKs.
 Map<String, dynamic> _toScriptCoverageJson(String scriptUri, Map<int, int> hitMap) {
   final Map<String, dynamic> json = <String, dynamic>{};
   final List<int> hits = <int>[];
   hitMap.forEach((int line, int hitCount) {
     hits.add(line);
     hits.add(hitCount);
   });
   json['source'] = scriptUri;
   json['script'] = <String, dynamic>{
     'type': '@Script',
     'fixedId': true,
     'id': 'libraries/1/scripts/${Uri.encodeComponent(scriptUri)}',
     'uri': scriptUri,
     '_kind': 'library',
   };
   json['hits'] = hits;
   return json;
 }
	// Copyright 2014 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	// @dart = 2.8

	import 'package:coverage/coverage.dart' as coverage;
	import 'package:meta/meta.dart';
	import 'package:vm_service/vm_service.dart' as vm_service;

	import '../base/file_system.dart';
	import '../base/io.dart';
	import '../base/process.dart';
	import '../globals_null_migrated.dart' as globals;
	import '../vmservice.dart';

	import 'test_device.dart';
	import 'watcher.dart';

	/// A class that's used to collect coverage data during tests.
	class CoverageCollector extends TestWatcher {
	CoverageCollector({this.libraryPredicate, this.verbose = true, @required this.packagesPath});

	final bool verbose;
	final String packagesPath;
	Map<String, Map<int, int>> _globalHitmap;
	bool Function(String) libraryPredicate;

	@override
	Future<void> handleFinishedTest(TestDevice testDevice) async {
	_logMessage('Starting coverage collection');
	await collectCoverage(testDevice);
	}

	void _logMessage(String line, { bool error = false }) {
	if (!verbose) {
	return;
	}
	if (error) {
	globals.printError(line);
	} else {
	globals.printTrace(line);
	}
	}

	void _addHitmap(Map<String, Map<int, int>> hitmap) {
	if (_globalHitmap == null) {
	_globalHitmap = hitmap;
	} else {
	coverage.mergeHitmaps(hitmap, _globalHitmap);
	}
	}

	/// Collects coverage for an isolate using the given `port`.
	///
	/// This should be called when the code whose coverage data is being collected
	/// has been run to completion so that all coverage data has been recorded.
	///
	/// The returned [Future] completes when the coverage is collected.
	Future<void> collectCoverageIsolate(Uri observatoryUri) async {
	assert(observatoryUri != null);
	_logMessage('collecting coverage data from $observatoryUri...');
	final Map<String, dynamic> data = await collect(observatoryUri, libraryPredicate);
	if (data == null) {
	throw Exception('Failed to collect coverage.');
	}
	assert(data != null);

	_logMessage('($observatoryUri): collected coverage data; merging...');
	_addHitmap(await coverage.createHitmap(
	data['coverage'] as List<Map<String, dynamic>>,
	packagesPath: packagesPath,
	checkIgnoredLines: true,
	));
	_logMessage('($observatoryUri): done merging coverage data into global coverage map.');
	}

	/// Collects coverage for the given [Process] using the given `port`.
	///
	/// This should be called when the code whose coverage data is being collected
	/// has been run to completion so that all coverage data has been recorded.
	///
	/// The returned [Future] completes when the coverage is collected.
	Future<void> collectCoverage(TestDevice testDevice) async {
	assert(testDevice != null);

	Map<String, dynamic> data;

	final Future<void> processComplete = testDevice.finished.catchError(
	(Object error) => throw Exception(
	'Failed to collect coverage, test device terminated prematurely with '
	'error: ${(error as TestDeviceException).message}.'),
	test: (Object error) => error is TestDeviceException,
	);

	final Future<void> collectionComplete = testDevice.observatoryUri
	.then((Uri observatoryUri) {
	_logMessage('collecting coverage data from $testDevice at $observatoryUri...');
	return collect(observatoryUri, libraryPredicate)
	.then<void>((Map<String, dynamic> result) {
	if (result == null) {
	throw Exception('Failed to collect coverage.');
	}
	_logMessage('Collected coverage data.');
	data = result;
	});
	});

	await Future.any<void>(<Future<void>>[ processComplete, collectionComplete ]);
	assert(data != null);

	_logMessage('Merging coverage data...');
	_addHitmap(await coverage.createHitmap(
	data['coverage'] as List<Map<String, dynamic>>,
	packagesPath: packagesPath,
	checkIgnoredLines: true,
	));
	_logMessage('Done merging coverage data into global coverage map.');
	}

	/// Returns a future that will complete with the formatted coverage data
	/// (using [formatter]) once all coverage data has been collected.
	///
	/// This will not start any collection tasks. It us up to the caller of to
	/// call [collectCoverage] for each process first.
	Future<String> finalizeCoverage({
	coverage.Formatter formatter,
	Directory coverageDirectory,
	}) async {
	if (_globalHitmap == null) {
	return null;
	}
	if (formatter == null) {
	final coverage.Resolver resolver = coverage.Resolver(packagesPath: packagesPath);
	final String packagePath = globals.fs.currentDirectory.path;
	final List<String> reportOn = coverageDirectory == null
	? <String>[globals.fs.path.join(packagePath, 'lib')]
	: <String>[coverageDirectory.path];
	formatter = coverage.LcovFormatter(resolver, reportOn: reportOn, basePath: packagePath);
	}
	final String result = await formatter.format(_globalHitmap);
	_globalHitmap = null;
	return result;
	}

	Future<bool> collectCoverageData(String coveragePath, { bool mergeCoverageData = false, Directory coverageDirectory }) async {
	final String coverageData = await finalizeCoverage(
	coverageDirectory: coverageDirectory,
	);
	_logMessage('coverage information collection complete');
	if (coverageData == null) {
	return false;
	}

	final File coverageFile = globals.fs.file(coveragePath)
	..createSync(recursive: true)
	..writeAsStringSync(coverageData, flush: true);
	_logMessage('wrote coverage data to $coveragePath (size=${coverageData.length})');

	const String baseCoverageData = 'coverage/lcov.base.info';
	if (mergeCoverageData) {
	if (!globals.fs.isFileSync(baseCoverageData)) {
	_logMessage('Missing "$baseCoverageData". Unable to merge coverage data.', error: true);
	return false;
	}

	if (globals.os.which('lcov') == null) {
	String installMessage = 'Please install lcov.';
	if (globals.platform.isLinux) {
	installMessage = 'Consider running "sudo apt-get install lcov".';
	} else if (globals.platform.isMacOS) {
	installMessage = 'Consider running "brew install lcov".';
	}
	_logMessage('Missing "lcov" tool. Unable to merge coverage data.\n$installMessage', error: true);
	return false;
	}

	final Directory tempDir = globals.fs.systemTempDirectory.createTempSync('flutter_tools_test_coverage.');
	try {
	final File sourceFile = coverageFile.copySync(globals.fs.path.join(tempDir.path, 'lcov.source.info'));
	final RunResult result = globals.processUtils.runSync(<String>[
	'lcov',
	'--add-tracefile', baseCoverageData,
	'--add-tracefile', sourceFile.path,
	'--output-file', coverageFile.path,
	]);
	if (result.exitCode != 0) {
	return false;
	}
	} finally {
	tempDir.deleteSync(recursive: true);
	}
	}
	return true;
	}

	@override
	Future<void> handleTestCrashed(TestDevice testDevice) async { }

	@override
	Future<void> handleTestTimedOut(TestDevice testDevice) async { }
	}

	Future<FlutterVmService> _defaultConnect(Uri serviceUri) {
	return connectToVmService(
	serviceUri, compression: CompressionOptions.compressionOff, logger: globals.logger,);
	}

	Future<Map<String, dynamic>> collect(Uri serviceUri, bool Function(String) libraryPredicate, {
	bool waitPaused = false,
	String debugName,
	Future<FlutterVmService> Function(Uri) connector = _defaultConnect,
	@visibleForTesting bool forceSequential = false,
	}) async {
	final FlutterVmService vmService = await connector(serviceUri);
	final Map<String, dynamic> result = await _getAllCoverage(vmService.service, libraryPredicate, forceSequential);
	await vmService.dispose();
	return result;
	}

	Future<Map<String, dynamic>> _getAllCoverage(
	vm_service.VmService service,
	bool Function(String) libraryPredicate,
	bool forceSequential,
	) async {
	final vm_service.Version version = await service.getVersion();
	final bool reportLines = (version.major == 3 && version.minor >= 51) \|\| version.major > 3;
	final vm_service.VM vm = await service.getVM();
	final List<Map<String, dynamic>> coverage = <Map<String, dynamic>>[];
	for (final vm_service.IsolateRef isolateRef in vm.isolates) {
	if (isolateRef.isSystemIsolate) {
	continue;
	}
	vm_service.ScriptList scriptList;
	try {
	scriptList = await service.getScripts(isolateRef.id);
	} on vm_service.SentinelException {
	continue;
	}

	final List<Future<void>> futures = <Future<void>>[];
	final Map<String, vm_service.Script> scripts = <String, vm_service.Script>{};
	final Map<String, vm_service.SourceReport> sourceReports = <String, vm_service.SourceReport>{};
	// For each ScriptRef loaded into the VM, load the corresponding Script and
	// SourceReport object.

	for (final vm_service.ScriptRef script in scriptList.scripts) {
	final String libraryUri = script.uri;
	if (!libraryPredicate(libraryUri)) {
	continue;
	}
	final String scriptId = script.id;
	final Future<void> getSourceReport = service.getSourceReport(
	isolateRef.id,
	<String>['Coverage'],
	scriptId: scriptId,
	forceCompile: true,
	reportLines: reportLines ? true : null,
	)
	.then((vm_service.SourceReport report) {
	sourceReports[scriptId] = report;
	});
	if (forceSequential) {
	await null;
	}
	futures.add(getSourceReport);
	if (reportLines) {
	continue;
	}
	final Future<void> getObject = service
	.getObject(isolateRef.id, scriptId)
	.then((vm_service.Obj response) {
	final vm_service.Script script = response as vm_service.Script;
	scripts[scriptId] = script;
	});
	futures.add(getObject);
	}
	await Future.wait(futures);
	_buildCoverageMap(scripts, sourceReports, coverage, reportLines);
	}
	return <String, dynamic>{'type': 'CodeCoverage', 'coverage': coverage};
	}

	// Build a hitmap of Uri -> Line -> Hit Count for each script object.
	void _buildCoverageMap(
	Map<String, vm_service.Script> scripts,
	Map<String, vm_service.SourceReport> sourceReports,
	List<Map<String, dynamic>> coverage,
	bool reportLines,
	) {
	final Map<String, Map<int, int>> hitMaps = <String, Map<int, int>>{};
	for (final String scriptId in sourceReports.keys) {
	final vm_service.SourceReport sourceReport = sourceReports[scriptId];
	for (final vm_service.SourceReportRange range in sourceReport.ranges) {
	final vm_service.SourceReportCoverage coverage = range.coverage;
	// Coverage reports may sometimes be null for a Script.
	if (coverage == null) {
	continue;
	}
	final vm_service.ScriptRef scriptRef = sourceReport.scripts[range.scriptIndex];
	final String uri = scriptRef.uri;

	hitMaps[uri] ??= <int, int>{};
	final Map<int, int> hitMap = hitMaps[uri];
	final List<int> hits = coverage.hits;
	final List<int> misses = coverage.misses;
	final List<dynamic> tokenPositions = scripts[scriptRef.id]?.tokenPosTable;
	// The token positions can be null if the script has no lines that may be
	// covered. It will also be null if reportLines is true.
	if (tokenPositions == null && !reportLines) {
	continue;
	}
	if (hits != null) {
	for (final int hit in hits) {
	final int line =
	reportLines ? hit : _lineAndColumn(hit, tokenPositions)[0];
	final int current = hitMap[line] ?? 0;
	hitMap[line] = current + 1;
	}
	}
	if (misses != null) {
	for (final int miss in misses) {
	final int line =
	reportLines ? miss : _lineAndColumn(miss, tokenPositions)[0];
	hitMap[line] ??= 0;
	}
	}
	}
	}
	hitMaps.forEach((String uri, Map<int, int> hitMap) {
	coverage.add(_toScriptCoverageJson(uri, hitMap));
	});
	}

	// Binary search the token position table for the line and column which
	// corresponds to each token position.
	// The format of this table is described in https://github.com/dart-lang/sdk/blob/main/runtime/vm/service/service.md#script
	List<int> _lineAndColumn(int position, List<dynamic> tokenPositions) {
	int min = 0;
	int max = tokenPositions.length;
	while (min < max) {
	final int mid = min + ((max - min) >> 1);
	final List<int> row = (tokenPositions[mid] as List<dynamic>).cast<int>();
	if (row[1] > position) {
	max = mid;
	} else {
	for (int i = 1; i < row.length; i += 2) {
	if (row[i] == position) {
	return <int>[row.first, row[i + 1]];
	}
	}
	min = mid + 1;
	}
	}
	throw StateError('Unreachable');
	}

	// Returns a JSON hit map backward-compatible with pre-1.16.0 SDKs.
	Map<String, dynamic> _toScriptCoverageJson(String scriptUri, Map<int, int> hitMap) {
	final Map<String, dynamic> json = <String, dynamic>{};
	final List<int> hits = <int>[];
	hitMap.forEach((int line, int hitCount) {
	hits.add(line);
	hits.add(hitCount);
	});
	json['source'] = scriptUri;
	json['script'] = <String, dynamic>{
	'type': '@Script',
	'fixedId': true,
	'id': 'libraries/1/scripts/${Uri.encodeComponent(scriptUri)}',
	'uri': scriptUri,
	'_kind': 'library',
	};
	json['hits'] = hits;
	return json;
	}