packages/analyzer/test/src/task/strong/strong_test_helper.dart - observatory_pub_packages - Git at Google

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.

 // TODO(jmesserly): this file needs to be refactored, it's a port from
 // package:dev_compiler's tests
 library test.src.task.strong.strong_test_helper;

 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/context/context.dart' show SdkAnalysisContext;
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:analyzer/src/generated/engine.dart' hide SdkAnalysisContext;
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/task/strong/checker.dart';
 import 'package:analyzer/src/task/strong/rules.dart';
 import 'package:logging/logging.dart'; // TODO(jmesserly): remove
 import 'package:source_span/source_span.dart'; // TODO(jmesserly): remove
 import 'package:unittest/unittest.dart';

 /// Run the checker on a program with files contents as indicated in
 /// [testFiles].
 ///
 /// This function makes several assumptions to make it easier to describe error
 /// expectations:
 ///
 ///   * a file named `/main.dart` exists in [testFiles].
 ///   * all expected failures are listed in the source code using comments
 ///   immediately in front of the AST node that should contain the error.
 ///   * errors are formatted as a token `level:Type`, where `level` is the
 ///   logging level were the error would be reported at, and `Type` is the
 ///   concrete subclass of [StaticInfo] that denotes the error.
 ///
 /// For example, to check that an assignment produces a warning about a boxing
 /// conversion, you can describe the test as follows:
 ///
 ///     testChecker({
 ///       '/main.dart': '''
 ///           testMethod() {
 ///             dynamic x = /*warning:Box*/3;
 ///           }
 ///       '''
 ///     });
 ///
 void testChecker(String name, Map<String, String> testFiles) {
   test(name, () {
     expect(testFiles.containsKey('/main.dart'), isTrue,
         reason: '`/main.dart` is missing in testFiles');

     var provider = new MemoryResourceProvider();
     testFiles.forEach((key, value) {
       var scheme = 'package:';
       if (key.startsWith(scheme)) {
         key = '/packages/${key.substring(scheme.length)}';
       }
       provider.newFile(key, value);
     });
     var uriResolver = new TestUriResolver(provider);
     // Enable task model strong mode
     AnalysisEngine.instance.useTaskModel = true;
     var context = AnalysisEngine.instance.createAnalysisContext();
     context.analysisOptions.strongMode = true;

     context.sourceFactory = new SourceFactory([
       new MockDartSdk(mockSdkSources, reportMissing: true).resolver,
       uriResolver
     ]);

     // Run the checker on /main.dart.
     Source mainSource = uriResolver.resolveAbsolute(new Uri.file('/main.dart'));
     var initialLibrary =
         context.resolveCompilationUnit2(mainSource, mainSource);

     var collector = new _ErrorCollector();
     var checker = new CodeChecker(
         new TypeRules(context.typeProvider), collector,
         hints: true);

     // Extract expectations from the comments in the test files, and
     // check that all errors we emit are included in the expected map.
     var allLibraries = reachableLibraries(initialLibrary.element.library);
     for (var lib in allLibraries) {
       for (var unit in lib.units) {
         var errors = <AnalysisError>[];
         collector.errors = errors;

         var source = unit.source;
         if (source.uri.scheme == 'dart') continue;

         var librarySource = context.getLibrariesContaining(source).single;
         var resolved = context.resolveCompilationUnit2(source, librarySource);
         checker.visitCompilationUnit(resolved);

         new _ExpectedErrorVisitor(errors).validate(resolved);
       }
     }
   });
 }

 class _ErrorCollector implements AnalysisErrorListener {
   List<AnalysisError> errors;
   final bool hints;
   _ErrorCollector({this.hints: true});

   void onError(AnalysisError error) {
     // Unless DDC hints are requested, filter them out.
     var HINT = ErrorSeverity.INFO.ordinal;
     if (hints || error.errorCode.errorSeverity.ordinal > HINT) {
       errors.add(error);
     }
   }
 }

 class TestUriResolver extends ResourceUriResolver {
   final MemoryResourceProvider provider;
   TestUriResolver(provider)
       : provider = provider,
         super(provider);

   @override
   Source resolveAbsolute(Uri uri, [Uri actualUri]) {
     if (uri.scheme == 'package') {
       return (provider.getResource('/packages/' + uri.path) as File)
           .createSource(uri);
     }
     return super.resolveAbsolute(uri, actualUri);
   }
 }

 class _ExpectedErrorVisitor extends UnifyingAstVisitor {
   final Set<AnalysisError> _actualErrors;
   CompilationUnit _unit;
   String _unitSourceCode;

   _ExpectedErrorVisitor(List<AnalysisError> actualErrors)
       : _actualErrors = new Set.from(actualErrors);

   validate(CompilationUnit unit) {
     _unit = unit;
     // This reads the file. Only safe because tests use MemoryFileSystem.
     _unitSourceCode = unit.element.source.contents.data;

     // Visit the compilation unit.
     unit.accept(this);

     if (_actualErrors.isNotEmpty) {
       var actualMsgs = _actualErrors.map(_formatActualError).join('\n');
       fail('Unexpected errors reported by checker:\n\n$actualMsgs');
     }
   }

   visitNode(AstNode node) {
     var token = node.beginToken;
     var comment = token.precedingComments;
     // Use error marker found in an immediately preceding comment,
     // and attach it to the outermost expression that starts at that token.
     if (comment != null) {
       while (comment.next != null) {
         comment = comment.next;
       }
       if (comment.end == token.offset && node.parent.beginToken != token) {
         var commentText = '$comment';
         var start = commentText.lastIndexOf('/*');
         var end = commentText.lastIndexOf('*/');
         if (start != -1 && end != -1) {
           expect(start, lessThan(end));
           var errors = commentText.substring(start + 2, end).split(',');
           var expectations =
               errors.map(_ErrorExpectation.parse).where((x) => x != null);

           for (var e in expectations) _expectError(node, e);
         }
       }
     }
     return super.visitNode(node);
   }

   void _expectError(AstNode node, _ErrorExpectation expected) {
     // See if we can find the expected error in our actual errors
     for (var actual in _actualErrors) {
       if (actual.offset == node.offset && actual.length == node.length) {
         var actualMsg = _formatActualError(actual);
         expect(_actualErrorLevel(actual), expected.level,
             reason: 'expected different error code at:\n\n$actualMsg');
         expect(errorCodeName(actual.errorCode), expected.typeName,
             reason: 'expected different error type at:\n\n$actualMsg');

         // We found it. Stop the search.
         _actualErrors.remove(actual);
         return;
       }
     }

     var span = _createSpan(node.offset, node.length);
     var levelName = expected.level.name.toLowerCase();
     var msg = span.message(expected.typeName, color: colorOf(levelName));
     fail('expected error was not reported at:\n\n$levelName: $msg');
   }

   Level _actualErrorLevel(AnalysisError actual) {
     return const <ErrorSeverity, Level>{
       ErrorSeverity.ERROR: Level.SEVERE,
       ErrorSeverity.WARNING: Level.WARNING,
       ErrorSeverity.INFO: Level.INFO
     }[actual.errorCode.errorSeverity];
   }

   String _formatActualError(AnalysisError actual) {
     var span = _createSpan(actual.offset, actual.length);
     var levelName = _actualErrorLevel(actual).name.toLowerCase();
     var msg = span.message(actual.message, color: colorOf(levelName));
     return '$levelName: [${errorCodeName(actual.errorCode)}] $msg';
   }

   SourceSpan _createSpan(int offset, int len) {
     return createSpanHelper(_unit.lineInfo, offset, offset + len,
         _unit.element.source, _unitSourceCode);
   }
 }

 SourceLocation locationForOffset(LineInfo lineInfo, Uri uri, int offset) {
   var loc = lineInfo.getLocation(offset);
   return new SourceLocation(offset,
       sourceUrl: uri, line: loc.lineNumber - 1, column: loc.columnNumber - 1);
 }

 SourceSpanWithContext createSpanHelper(
     LineInfo lineInfo, int start, int end, Source source, String content) {
   var startLoc = locationForOffset(lineInfo, source.uri, start);
   var endLoc = locationForOffset(lineInfo, source.uri, end);

   var lineStart = startLoc.offset - startLoc.column;
   // Find the end of the line. This is not exposed directly on LineInfo, but
   // we can find it pretty easily.
   // TODO(jmesserly): for now we do the simple linear scan. Ideally we can get
   // some help from the LineInfo API.
   int lineEnd = endLoc.offset;
   int lineNum = lineInfo.getLocation(lineEnd).lineNumber;
   while (lineEnd < content.length &&
       lineInfo.getLocation(++lineEnd).lineNumber == lineNum);

   var text = content.substring(start, end);
   var lineText = content.substring(lineStart, lineEnd);
   return new SourceSpanWithContext(startLoc, endLoc, text, lineText);
 }

 /// Describes an expected message that should be produced by the checker.
 class _ErrorExpectation {
   final Level level;
   final String typeName;
   _ErrorExpectation(this.level, this.typeName);

   static _ErrorExpectation _parse(String descriptor) {
     var tokens = descriptor.split(':');
     expect(tokens.length, 2, reason: 'invalid error descriptor');
     var name = tokens[0].toUpperCase();
     var typeName = tokens[1];

     var level =
         Level.LEVELS.firstWhere((l) => l.name == name, orElse: () => null);
     expect(level, isNotNull,
         reason: 'invalid level in error descriptor: `${tokens[0]}`');
     expect(typeName, isNotNull,
         reason: 'invalid type in error descriptor: ${tokens[1]}');
     return new _ErrorExpectation(level, typeName);
   }

   static _ErrorExpectation parse(String descriptor) {
     descriptor = descriptor.trim();
     var tokens = descriptor.split(' ');
     if (tokens.length == 1) return _parse(tokens[0]);
     expect(tokens.length, 4, reason: 'invalid error descriptor');
     expect(tokens[1], "should", reason: 'invalid error descriptor');
     expect(tokens[2], "be", reason: 'invalid error descriptor');
     if (tokens[0] == "pass") return null;
     // TODO(leafp) For now, we just use whatever the current expectation is,
     // eventually we could do more automated reporting here.
     return _parse(tokens[0]);
   }

   String toString() => '$level $typeName';
 }

 /// Dart SDK which contains a mock implementation of the SDK libraries. May be
 /// used to speed up execution when most of the core libraries is not needed.
 class MockDartSdk implements DartSdk {
   final Map<Uri, _MockSdkSource> _sources = {};
   final bool reportMissing;
   final Map<String, SdkLibrary> _libs = {};
   final String sdkVersion = '0';
   List<String> get uris => _sources.keys.map((uri) => '$uri').toList();
   final AnalysisContext context = new SdkAnalysisContext();
   DartUriResolver _resolver;
   DartUriResolver get resolver => _resolver;

   MockDartSdk(Map<String, String> sources, {this.reportMissing}) {
     sources.forEach((uriString, contents) {
       var uri = Uri.parse(uriString);
       _sources[uri] = new _MockSdkSource(uri, contents);
       _libs[uriString] = new SdkLibraryImpl(uri.path)
         ..setDart2JsLibrary()
         ..setVmLibrary();
     });
     _resolver = new DartUriResolver(this);
     context.sourceFactory = new SourceFactory([_resolver]);
   }

   List<SdkLibrary> get sdkLibraries => _libs.values.toList();
   SdkLibrary getSdkLibrary(String dartUri) => _libs[dartUri];
   Source mapDartUri(String dartUri) => _getSource(Uri.parse(dartUri));

   Source fromEncoding(UriKind kind, Uri uri) {
     if (kind != UriKind.DART_URI) {
       throw new UnsupportedError('expected dart: uri kind, got $kind.');
     }
     return _getSource(uri);
   }

   Source _getSource(Uri uri) {
     var src = _sources[uri];
     if (src == null) {
       if (reportMissing) print('warning: missing mock for $uri.');
       _sources[uri] =
           src = new _MockSdkSource(uri, 'library dart.${uri.path};');
     }
     return src;
   }

   @override
   Source fromFileUri(Uri uri) {
     throw new UnsupportedError('MockDartSdk.fromFileUri');
   }
 }

 class _MockSdkSource implements Source {
   /// Absolute URI which this source can be imported from.
   final Uri uri;
   final String _contents;

   _MockSdkSource(this.uri, this._contents);

   bool exists() => true;

   int get hashCode => uri.hashCode;

   final int modificationStamp = 1;

   TimestampedData<String> get contents =>
       new TimestampedData(modificationStamp, _contents);

   String get encoding => "${uriKind.encoding}$uri";

   Source get source => this;

   String get fullName => shortName;

   String get shortName => uri.path;

   UriKind get uriKind => UriKind.DART_URI;

   bool get isInSystemLibrary => true;

   Source resolveRelative(Uri relativeUri) =>
       throw new UnsupportedError('not expecting relative urls in dart: mocks');

   Uri resolveRelativeUri(Uri relativeUri) =>
       throw new UnsupportedError('not expecting relative urls in dart: mocks');
 }

 /// Sample mock SDK sources.
 final Map<String, String> mockSdkSources = {
   // The list of types below is derived from:
   //   * types we use via our smoke queries, including HtmlElement and
   //     types from `_typeHandlers` (deserialize.dart)
   //   * types that are used internally by the resolver (see
   //   _initializeFrom in resolver.dart).
   'dart:core': '''
         library dart.core;

         void print(Object o) {}

         class Object {
           int get hashCode {}
           Type get runtimeType {}
           String toString(){}
           bool ==(other){}
         }
         class Function {}
         class StackTrace {}
         class Symbol {}
         class Type {}

         class String {
           String operator +(String other) {}
         }
         class bool {}
         class num {
           num operator +(num other) {}
         }
         class int extends num {
           bool operator<(num other) {}
           int operator-() {}
         }
         class double extends num {}
         class DateTime {}
         class Null {}

         class Deprecated {
           final String expires;
           const Deprecated(this.expires);
         }
         const Object deprecated = const Deprecated("next release");
         class _Override { const _Override(); }
         const Object override = const _Override();
         class _Proxy { const _Proxy(); }
         const Object proxy = const _Proxy();

         class Iterable<E> {
           fold(initialValue, combine(previousValue, E element)) {}
           Iterable map(f(E element)) {}
         }
         class List<E> implements Iterable<E> {
           List([int length]);
           List.filled(int length, E fill);
         }
         class Map<K, V> {
           Iterable<K> get keys {}
         }
         ''',
   'dart:async': '''
         class Future<T> {
           Future(computation()) {}
           Future.value(T t) {}
           Future then(onValue(T value)) {}
           static Future<List> wait(Iterable<Future> futures) {}
         }
         class Stream<T> {}
   ''',
   'dart:html': '''
         library dart.html;
         class HtmlElement {}
         ''',
   'dart:math': '''
         library dart.math;
         class Random {
           bool nextBool() {}
         }
         num min(num x, num y) {}
         num max(num x, num y) {}
         ''',
 };

 /// Returns all libraries transitively imported or exported from [start].
 List<LibraryElement> reachableLibraries(LibraryElement start) {
   var results = <LibraryElement>[];
   var seen = new Set();
   void find(LibraryElement lib) {
     if (seen.contains(lib)) return;
     seen.add(lib);
     results.add(lib);
     lib.importedLibraries.forEach(find);
     lib.exportedLibraries.forEach(find);
   }
   find(start);
   return results;
 }

 String errorCodeName(ErrorCode errorCode) {
   var name = errorCode.name;
   final prefix = 'dev_compiler.';
   if (name.startsWith(prefix)) {
     return name.substring(prefix.length);
   } else {
     // TODO(jmesserly): this is for backwards compat, but not sure it's very
     // useful to log this.
     return 'AnalyzerMessage';
   }
 }

 /// Returns an ANSII color escape sequence corresponding to [levelName]. Colors
 /// are defined for: severe, error, warning, or info. Returns null if the level
 /// name is not recognized.
 String colorOf(String levelName) {
   levelName = levelName.toLowerCase();
   if (levelName == 'shout' || levelName == 'severe' || levelName == 'error') {
     return _RED_COLOR;
   }
   if (levelName == 'warning') return _MAGENTA_COLOR;
   if (levelName == 'info') return _CYAN_COLOR;
   return null;
 }

 const String _RED_COLOR = '\u001b[31m';
 const String _MAGENTA_COLOR = '\u001b[35m';
 const String _CYAN_COLOR = '\u001b[36m';
 const String GREEN_COLOR = '\u001b[32m';
 const String NO_COLOR = '\u001b[0m';
	// Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file
	// for details. All rights reserved. Use of this source code is governed by a
	// BSD-style license that can be found in the LICENSE file.

	// TODO(jmesserly): this file needs to be refactored, it's a port from
	// package:dev_compiler's tests
	library test.src.task.strong.strong_test_helper;

	import 'package:analyzer/file_system/file_system.dart';
	import 'package:analyzer/file_system/memory_file_system.dart';
	import 'package:analyzer/src/context/context.dart' show SdkAnalysisContext;
	import 'package:analyzer/src/generated/ast.dart';
	import 'package:analyzer/src/generated/element.dart';
	import 'package:analyzer/src/generated/engine.dart' hide SdkAnalysisContext;
	import 'package:analyzer/src/generated/error.dart';
	import 'package:analyzer/src/generated/sdk.dart';
	import 'package:analyzer/src/generated/source.dart';
	import 'package:analyzer/src/task/strong/checker.dart';
	import 'package:analyzer/src/task/strong/rules.dart';
	import 'package:logging/logging.dart'; // TODO(jmesserly): remove
	import 'package:source_span/source_span.dart'; // TODO(jmesserly): remove
	import 'package:unittest/unittest.dart';

	/// Run the checker on a program with files contents as indicated in
	/// [testFiles].
	///
	/// This function makes several assumptions to make it easier to describe error
	/// expectations:
	///
	/// * a file named `/main.dart` exists in [testFiles].
	/// * all expected failures are listed in the source code using comments
	/// immediately in front of the AST node that should contain the error.
	/// * errors are formatted as a token `level:Type`, where `level` is the
	/// logging level were the error would be reported at, and `Type` is the
	/// concrete subclass of [StaticInfo] that denotes the error.
	///
	/// For example, to check that an assignment produces a warning about a boxing
	/// conversion, you can describe the test as follows:
	///
	/// testChecker({
	/// '/main.dart': '''
	/// testMethod() {
	/// dynamic x = /warning:Box/3;
	/// }
	/// '''
	/// });
	///
	void testChecker(String name, Map<String, String> testFiles) {
	test(name, () {
	expect(testFiles.containsKey('/main.dart'), isTrue,
	reason: '`/main.dart` is missing in testFiles');

	var provider = new MemoryResourceProvider();
	testFiles.forEach((key, value) {
	var scheme = 'package:';
	if (key.startsWith(scheme)) {
	key = '/packages/${key.substring(scheme.length)}';
	}
	provider.newFile(key, value);
	});
	var uriResolver = new TestUriResolver(provider);
	// Enable task model strong mode
	AnalysisEngine.instance.useTaskModel = true;
	var context = AnalysisEngine.instance.createAnalysisContext();
	context.analysisOptions.strongMode = true;

	context.sourceFactory = new SourceFactory([
	new MockDartSdk(mockSdkSources, reportMissing: true).resolver,
	uriResolver
	]);

	// Run the checker on /main.dart.
	Source mainSource = uriResolver.resolveAbsolute(new Uri.file('/main.dart'));
	var initialLibrary =
	context.resolveCompilationUnit2(mainSource, mainSource);

	var collector = new _ErrorCollector();
	var checker = new CodeChecker(
	new TypeRules(context.typeProvider), collector,
	hints: true);

	// Extract expectations from the comments in the test files, and
	// check that all errors we emit are included in the expected map.
	var allLibraries = reachableLibraries(initialLibrary.element.library);
	for (var lib in allLibraries) {
	for (var unit in lib.units) {
	var errors = <AnalysisError>[];
	collector.errors = errors;

	var source = unit.source;
	if (source.uri.scheme == 'dart') continue;

	var librarySource = context.getLibrariesContaining(source).single;
	var resolved = context.resolveCompilationUnit2(source, librarySource);
	checker.visitCompilationUnit(resolved);

	new _ExpectedErrorVisitor(errors).validate(resolved);
	}
	}
	});
	}

	class _ErrorCollector implements AnalysisErrorListener {
	List<AnalysisError> errors;
	final bool hints;
	_ErrorCollector({this.hints: true});

	void onError(AnalysisError error) {
	// Unless DDC hints are requested, filter them out.
	var HINT = ErrorSeverity.INFO.ordinal;
	if (hints \|\| error.errorCode.errorSeverity.ordinal > HINT) {
	errors.add(error);
	}
	}
	}

	class TestUriResolver extends ResourceUriResolver {
	final MemoryResourceProvider provider;
	TestUriResolver(provider)
	: provider = provider,
	super(provider);

	@override
	Source resolveAbsolute(Uri uri, [Uri actualUri]) {
	if (uri.scheme == 'package') {
	return (provider.getResource('/packages/' + uri.path) as File)
	.createSource(uri);
	}
	return super.resolveAbsolute(uri, actualUri);
	}
	}

	class _ExpectedErrorVisitor extends UnifyingAstVisitor {
	final Set<AnalysisError> _actualErrors;
	CompilationUnit _unit;
	String _unitSourceCode;

	_ExpectedErrorVisitor(List<AnalysisError> actualErrors)
	: _actualErrors = new Set.from(actualErrors);

	validate(CompilationUnit unit) {
	_unit = unit;
	// This reads the file. Only safe because tests use MemoryFileSystem.
	_unitSourceCode = unit.element.source.contents.data;

	// Visit the compilation unit.
	unit.accept(this);

	if (_actualErrors.isNotEmpty) {
	var actualMsgs = _actualErrors.map(_formatActualError).join('\n');
	fail('Unexpected errors reported by checker:\n\n$actualMsgs');
	}
	}

	visitNode(AstNode node) {
	var token = node.beginToken;
	var comment = token.precedingComments;
	// Use error marker found in an immediately preceding comment,
	// and attach it to the outermost expression that starts at that token.
	if (comment != null) {
	while (comment.next != null) {
	comment = comment.next;
	}
	if (comment.end == token.offset && node.parent.beginToken != token) {
	var commentText = '$comment';
	var start = commentText.lastIndexOf('/*');
	var end = commentText.lastIndexOf('*/');
	if (start != -1 && end != -1) {
	expect(start, lessThan(end));
	var errors = commentText.substring(start + 2, end).split(',');
	var expectations =
	errors.map(_ErrorExpectation.parse).where((x) => x != null);

	for (var e in expectations) _expectError(node, e);
	}
	}
	}
	return super.visitNode(node);
	}

	void _expectError(AstNode node, _ErrorExpectation expected) {
	// See if we can find the expected error in our actual errors
	for (var actual in _actualErrors) {
	if (actual.offset == node.offset && actual.length == node.length) {
	var actualMsg = _formatActualError(actual);
	expect(_actualErrorLevel(actual), expected.level,
	reason: 'expected different error code at:\n\n$actualMsg');
	expect(errorCodeName(actual.errorCode), expected.typeName,
	reason: 'expected different error type at:\n\n$actualMsg');

	// We found it. Stop the search.
	_actualErrors.remove(actual);
	return;
	}
	}

	var span = _createSpan(node.offset, node.length);
	var levelName = expected.level.name.toLowerCase();
	var msg = span.message(expected.typeName, color: colorOf(levelName));
	fail('expected error was not reported at:\n\n$levelName: $msg');
	}

	Level _actualErrorLevel(AnalysisError actual) {
	return const <ErrorSeverity, Level>{
	ErrorSeverity.ERROR: Level.SEVERE,
	ErrorSeverity.WARNING: Level.WARNING,
	ErrorSeverity.INFO: Level.INFO
	}[actual.errorCode.errorSeverity];
	}

	String _formatActualError(AnalysisError actual) {
	var span = _createSpan(actual.offset, actual.length);
	var levelName = _actualErrorLevel(actual).name.toLowerCase();
	var msg = span.message(actual.message, color: colorOf(levelName));
	return '$levelName: [${errorCodeName(actual.errorCode)}] $msg';
	}

	SourceSpan _createSpan(int offset, int len) {
	return createSpanHelper(_unit.lineInfo, offset, offset + len,
	_unit.element.source, _unitSourceCode);
	}
	}

	SourceLocation locationForOffset(LineInfo lineInfo, Uri uri, int offset) {
	var loc = lineInfo.getLocation(offset);
	return new SourceLocation(offset,
	sourceUrl: uri, line: loc.lineNumber - 1, column: loc.columnNumber - 1);
	}

	SourceSpanWithContext createSpanHelper(
	LineInfo lineInfo, int start, int end, Source source, String content) {
	var startLoc = locationForOffset(lineInfo, source.uri, start);
	var endLoc = locationForOffset(lineInfo, source.uri, end);

	var lineStart = startLoc.offset - startLoc.column;
	// Find the end of the line. This is not exposed directly on LineInfo, but
	// we can find it pretty easily.
	// TODO(jmesserly): for now we do the simple linear scan. Ideally we can get
	// some help from the LineInfo API.
	int lineEnd = endLoc.offset;
	int lineNum = lineInfo.getLocation(lineEnd).lineNumber;
	while (lineEnd < content.length &&
	lineInfo.getLocation(++lineEnd).lineNumber == lineNum);

	var text = content.substring(start, end);
	var lineText = content.substring(lineStart, lineEnd);
	return new SourceSpanWithContext(startLoc, endLoc, text, lineText);
	}

	/// Describes an expected message that should be produced by the checker.
	class _ErrorExpectation {
	final Level level;
	final String typeName;
	_ErrorExpectation(this.level, this.typeName);

	static _ErrorExpectation _parse(String descriptor) {
	var tokens = descriptor.split(':');
	expect(tokens.length, 2, reason: 'invalid error descriptor');
	var name = tokens[0].toUpperCase();
	var typeName = tokens[1];

	var level =
	Level.LEVELS.firstWhere((l) => l.name == name, orElse: () => null);
	expect(level, isNotNull,
	reason: 'invalid level in error descriptor: `${tokens[0]}`');
	expect(typeName, isNotNull,
	reason: 'invalid type in error descriptor: ${tokens[1]}');
	return new _ErrorExpectation(level, typeName);
	}

	static _ErrorExpectation parse(String descriptor) {
	descriptor = descriptor.trim();
	var tokens = descriptor.split(' ');
	if (tokens.length == 1) return _parse(tokens[0]);
	expect(tokens.length, 4, reason: 'invalid error descriptor');
	expect(tokens[1], "should", reason: 'invalid error descriptor');
	expect(tokens[2], "be", reason: 'invalid error descriptor');
	if (tokens[0] == "pass") return null;
	// TODO(leafp) For now, we just use whatever the current expectation is,
	// eventually we could do more automated reporting here.
	return _parse(tokens[0]);
	}

	String toString() => '$level $typeName';
	}

	/// Dart SDK which contains a mock implementation of the SDK libraries. May be
	/// used to speed up execution when most of the core libraries is not needed.
	class MockDartSdk implements DartSdk {
	final Map<Uri, _MockSdkSource> _sources = {};
	final bool reportMissing;
	final Map<String, SdkLibrary> _libs = {};
	final String sdkVersion = '0';
	List<String> get uris => _sources.keys.map((uri) => '$uri').toList();
	final AnalysisContext context = new SdkAnalysisContext();
	DartUriResolver _resolver;
	DartUriResolver get resolver => _resolver;

	MockDartSdk(Map<String, String> sources, {this.reportMissing}) {
	sources.forEach((uriString, contents) {
	var uri = Uri.parse(uriString);
	_sources[uri] = new _MockSdkSource(uri, contents);
	_libs[uriString] = new SdkLibraryImpl(uri.path)
	..setDart2JsLibrary()
	..setVmLibrary();
	});
	_resolver = new DartUriResolver(this);
	context.sourceFactory = new SourceFactory([_resolver]);
	}

	List<SdkLibrary> get sdkLibraries => _libs.values.toList();
	SdkLibrary getSdkLibrary(String dartUri) => _libs[dartUri];
	Source mapDartUri(String dartUri) => _getSource(Uri.parse(dartUri));

	Source fromEncoding(UriKind kind, Uri uri) {
	if (kind != UriKind.DART_URI) {
	throw new UnsupportedError('expected dart: uri kind, got $kind.');
	}
	return _getSource(uri);
	}

	Source _getSource(Uri uri) {
	var src = _sources[uri];
	if (src == null) {
	if (reportMissing) print('warning: missing mock for $uri.');
	_sources[uri] =
	src = new _MockSdkSource(uri, 'library dart.${uri.path};');
	}
	return src;
	}

	@override
	Source fromFileUri(Uri uri) {
	throw new UnsupportedError('MockDartSdk.fromFileUri');
	}
	}

	class _MockSdkSource implements Source {
	/// Absolute URI which this source can be imported from.
	final Uri uri;
	final String _contents;

	_MockSdkSource(this.uri, this._contents);

	bool exists() => true;

	int get hashCode => uri.hashCode;

	final int modificationStamp = 1;

	TimestampedData<String> get contents =>
	new TimestampedData(modificationStamp, _contents);

	String get encoding => "${uriKind.encoding}$uri";

	Source get source => this;

	String get fullName => shortName;

	String get shortName => uri.path;

	UriKind get uriKind => UriKind.DART_URI;

	bool get isInSystemLibrary => true;

	Source resolveRelative(Uri relativeUri) =>
	throw new UnsupportedError('not expecting relative urls in dart: mocks');

	Uri resolveRelativeUri(Uri relativeUri) =>
	throw new UnsupportedError('not expecting relative urls in dart: mocks');
	}

	/// Sample mock SDK sources.
	final Map<String, String> mockSdkSources = {
	// The list of types below is derived from:
	// * types we use via our smoke queries, including HtmlElement and
	// types from `_typeHandlers` (deserialize.dart)
	// * types that are used internally by the resolver (see
	// _initializeFrom in resolver.dart).
	'dart:core': '''
	library dart.core;

	void print(Object o) {}

	class Object {
	int get hashCode {}
	Type get runtimeType {}
	String toString(){}
	bool ==(other){}
	}
	class Function {}
	class StackTrace {}
	class Symbol {}
	class Type {}

	class String {
	String operator +(String other) {}
	}
	class bool {}
	class num {
	num operator +(num other) {}
	}
	class int extends num {
	bool operator<(num other) {}
	int operator-() {}
	}
	class double extends num {}
	class DateTime {}
	class Null {}

	class Deprecated {
	final String expires;
	const Deprecated(this.expires);
	}
	const Object deprecated = const Deprecated("next release");
	class _Override { const _Override(); }
	const Object override = const _Override();
	class _Proxy { const _Proxy(); }
	const Object proxy = const _Proxy();

	class Iterable<E> {
	fold(initialValue, combine(previousValue, E element)) {}
	Iterable map(f(E element)) {}
	}
	class List<E> implements Iterable<E> {
	List([int length]);
	List.filled(int length, E fill);
	}
	class Map<K, V> {
	Iterable<K> get keys {}
	}
	''',
	'dart:async': '''
	class Future<T> {
	Future(computation()) {}
	Future.value(T t) {}
	Future then(onValue(T value)) {}
	static Future<List> wait(Iterable<Future> futures) {}
	}
	class Stream<T> {}
	''',
	'dart:html': '''
	library dart.html;
	class HtmlElement {}
	''',
	'dart:math': '''
	library dart.math;
	class Random {
	bool nextBool() {}
	}
	num min(num x, num y) {}
	num max(num x, num y) {}
	''',
	};

	/// Returns all libraries transitively imported or exported from [start].
	List<LibraryElement> reachableLibraries(LibraryElement start) {
	var results = <LibraryElement>[];
	var seen = new Set();
	void find(LibraryElement lib) {
	if (seen.contains(lib)) return;
	seen.add(lib);
	results.add(lib);
	lib.importedLibraries.forEach(find);
	lib.exportedLibraries.forEach(find);
	}
	find(start);
	return results;
	}

	String errorCodeName(ErrorCode errorCode) {
	var name = errorCode.name;
	final prefix = 'dev_compiler.';
	if (name.startsWith(prefix)) {
	return name.substring(prefix.length);
	} else {
	// TODO(jmesserly): this is for backwards compat, but not sure it's very
	// useful to log this.
	return 'AnalyzerMessage';
	}
	}

	/// Returns an ANSII color escape sequence corresponding to [levelName]. Colors
	/// are defined for: severe, error, warning, or info. Returns null if the level
	/// name is not recognized.
	String colorOf(String levelName) {
	levelName = levelName.toLowerCase();
	if (levelName == 'shout' \|\| levelName == 'severe' \|\| levelName == 'error') {
	return _RED_COLOR;
	}
	if (levelName == 'warning') return _MAGENTA_COLOR;
	if (levelName == 'info') return _CYAN_COLOR;
	return null;
	}

	const String _RED_COLOR = '\u001b[31m';
	const String _MAGENTA_COLOR = '\u001b[35m';
	const String _CYAN_COLOR = '\u001b[36m';
	const String GREEN_COLOR = '\u001b[32m';
	const String NO_COLOR = '\u001b[0m';