Separate fasta and analyzer scanner tests.

pkg/front_end/test/scanner_test.dart

Index: pkg/front_end/test/scanner_test.dart
diff --git a/pkg/front_end/test/scanner_test.dart b/pkg/front_end/test/scanner_test.dart
index fab987ba323ca89af249c70bbd48bea0c92119ed..2a46caf3531d7ffb3098f4e4e7c8b09fec87f061 100644
--- a/pkg/front_end/test/scanner_test.dart
+++ b/pkg/front_end/test/scanner_test.dart
@@ -4,11 +4,6 @@
 
 import 'package:front_end/src/base/errors.dart';
 import 'package:front_end/src/base/jenkins_smi_hash.dart';
-import 'package:front_end/src/fasta/scanner/error_token.dart' as fasta;
-import 'package:front_end/src/fasta/scanner/keyword.dart' as fasta;
-import 'package:front_end/src/fasta/scanner/string_scanner.dart' as fasta;
-import 'package:front_end/src/fasta/scanner/token.dart' as fasta;
-import 'package:front_end/src/fasta/scanner/token_constants.dart' as fasta;
 import 'package:front_end/src/scanner/errors.dart';
 import 'package:front_end/src/scanner/reader.dart';
 import 'package:front_end/src/scanner/scanner.dart';
@@ -21,7 +16,6 @@ main() {
     defineReflectiveTests(CharSequenceReaderTest);
     defineReflectiveTests(KeywordStateTest);
     defineReflectiveTests(ScannerTest);
-    defineReflectiveTests(ScannerTest_Fasta);
     defineReflectiveTests(TokenTypeTest);
   });
 }
@@ -74,6 +68,18 @@ class CharSequenceReaderTest {
   }
 }
 
+class ErrorListener {
+  final errors = <TestError>[];
+
+  void assertErrors(List<TestError> expectedErrors) {
+    expect(errors, unorderedEquals(expectedErrors));
+  }
+
+  void assertNoErrors() {
+    assertErrors([]);
+  }
+}
+
 @reflectiveTest
 class KeywordStateTest {
   void test_KeywordState() {
@@ -121,13 +127,7 @@ class KeywordStateTest {
 @reflectiveTest
 class ScannerTest extends ScannerTestBase {
   @override
-  @failingTest
-  void test_incomplete_string_interpolation() {
-    super.test_incomplete_string_interpolation();
-  }
-
-  @override
-  Token _scanWithListener(String source, _ErrorListener listener,
+  Token scanWithListener(String source, ErrorListener listener,
       {bool genericMethodComments: false,
       bool lazyAssignmentOperators: false}) {
     Scanner scanner =
@@ -136,515 +136,18 @@ class ScannerTest extends ScannerTestBase {
     scanner.scanLazyAssignmentOperators = lazyAssignmentOperators;
     return scanner.tokenize();
   }
-}
-
-@reflectiveTest
-class ScannerTest_Fasta extends ScannerTestBase {
-  final _keywordMap = {
-    "assert": Keyword.ASSERT,
-    "break": Keyword.BREAK,
-    "case": Keyword.CASE,
-    "catch": Keyword.CATCH,
-    "class": Keyword.CLASS,
-    "const": Keyword.CONST,
-    "continue": Keyword.CONTINUE,
-    "default": Keyword.DEFAULT,
-    "do": Keyword.DO,
-    "else": Keyword.ELSE,
-    "enum": Keyword.ENUM,
-    "extends": Keyword.EXTENDS,
-    "false": Keyword.FALSE,
-    "final": Keyword.FINAL,
-    "finally": Keyword.FINALLY,
-    "for": Keyword.FOR,
-    "if": Keyword.IF,
-    "in": Keyword.IN,
-    "new": Keyword.NEW,
-    "null": Keyword.NULL,
-    "rethrow": Keyword.RETHROW,
-    "return": Keyword.RETURN,
-    "super": Keyword.SUPER,
-    "switch": Keyword.SWITCH,
-    "this": Keyword.THIS,
-    "throw": Keyword.THROW,
-    "true": Keyword.TRUE,
-    "try": Keyword.TRY,
-    "var": Keyword.VAR,
-    "void": Keyword.VOID,
-    "while": Keyword.WHILE,
-    "with": Keyword.WITH,
-    "is": Keyword.IS,
-    "abstract": Keyword.ABSTRACT,
-    "as": Keyword.AS,
-    "covariant": Keyword.COVARIANT,
-    "dynamic": Keyword.DYNAMIC,
-    "export": Keyword.EXPORT,
-    "external": Keyword.EXTERNAL,
-    "factory": Keyword.FACTORY,
-    "get": Keyword.GET,
-    "implements": Keyword.IMPLEMENTS,
-    "import": Keyword.IMPORT,
-    "library": Keyword.LIBRARY,
-    "operator": Keyword.OPERATOR,
-    "part": Keyword.PART,
-    "set": Keyword.SET,
-    "static": Keyword.STATIC,
-    "typedef": Keyword.TYPEDEF,
-    "deferred": Keyword.DEFERRED,
-  };
-
-  @override
-  @failingTest
-  void test_ampersand_ampersand_eq() {
-    // TODO(paulberry,ahe): Fasta doesn't support `&&=` yet
-    super.test_ampersand_ampersand_eq();
-  }
 
   @override
   @failingTest
-  void test_bar_bar_eq() {
-    // TODO(paulberry,ahe): Fasta doesn't support `||=` yet
-    super.test_bar_bar_eq();
-  }
-
-  @override
-  @failingTest
-  void test_comment_generic_method_type_assign() {
-    // TODO(paulberry,ahe): Fasta doesn't support generic method comment syntax.
-    super.test_comment_generic_method_type_assign();
-  }
-
-  @override
-  @failingTest
-  void test_comment_generic_method_type_list() {
-    // TODO(paulberry,ahe): Fasta doesn't support generic method comment syntax.
-    super.test_comment_generic_method_type_list();
-  }
-
-  @override
-  @failingTest
-  void test_index() {
-    // TODO(paulberry,ahe): "[]" should be parsed as a single token.
-    super.test_index();
-  }
-
-  @override
-  @failingTest
-  void test_index_eq() {
-    // TODO(paulberry,ahe): "[]=" should be parsed as a single token.
-    super.test_index_eq();
-  }
-
-  @override
-  @failingTest
-  void test_scriptTag_withArgs() {
-    // TODO(paulberry,ahe): script tags are needed by analyzer.
-    super.test_scriptTag_withArgs();
-  }
-
-  @override
-  @failingTest
-  void test_scriptTag_withoutSpace() {
-    // TODO(paulberry,ahe): script tags are needed by analyzer.
-    super.test_scriptTag_withoutSpace();
-  }
-
-  @override
-  @failingTest
-  void test_scriptTag_withSpace() {
-    // TODO(paulberry,ahe): script tags are needed by analyzer.
-    super.test_scriptTag_withSpace();
-  }
-
-  @override
-  @failingTest
-  void test_string_multi_unterminated() {
-    // TODO(paulberry,ahe): bad error recovery.
-    super.test_string_multi_unterminated();
-  }
-
-  @override
-  @failingTest
-  void test_string_multi_unterminated_interpolation_block() {
-    // TODO(paulberry,ahe): bad error recovery.
-    super.test_string_multi_unterminated_interpolation_block();
-  }
-
-  @override
-  @failingTest
-  void test_string_multi_unterminated_interpolation_identifier() {
-    // TODO(paulberry,ahe): bad error recovery.
-    super.test_string_multi_unterminated_interpolation_identifier();
-  }
-
-  @override
-  @failingTest
-  void test_string_raw_multi_unterminated() {
-    // TODO(paulberry,ahe): bad error recovery.
-    super.test_string_raw_multi_unterminated();
-  }
-
-  @override
-  @failingTest
-  void test_string_raw_simple_unterminated_eof() {
-    // TODO(paulberry,ahe): bad error recovery.
-    super.test_string_raw_simple_unterminated_eof();
-  }
-
-  @override
-  @failingTest
-  void test_string_raw_simple_unterminated_eol() {
-    // TODO(paulberry,ahe): bad error recovery.
-    super.test_string_raw_simple_unterminated_eol();
-  }
-
-  @override
-  @failingTest
-  void test_string_simple_unterminated_eof() {
-    // TODO(paulberry,ahe): bad error recovery.
-    super.test_string_simple_unterminated_eof();
-  }
-
-  @override
-  @failingTest
-  void test_string_simple_unterminated_eol() {
-    // TODO(paulberry,ahe): bad error recovery.
-    super.test_string_simple_unterminated_eol();
-  }
-
-  @override
-  @failingTest
-  void test_string_simple_unterminated_interpolation_block() {
-    // TODO(paulberry,ahe): bad error recovery.
-    super.test_string_simple_unterminated_interpolation_block();
-  }
-
-  @override
-  @failingTest
-  void test_string_simple_unterminated_interpolation_identifier() {
-    // TODO(paulberry,ahe): bad error recovery.
-    super.test_string_simple_unterminated_interpolation_identifier();
-  }
-
-  @override
-  Token _scanWithListener(String source, _ErrorListener listener,
-      {bool genericMethodComments: false,
-      bool lazyAssignmentOperators: false}) {
-    if (genericMethodComments) {
-      // Fasta doesn't support generic method comments.
-      // TODO(paulberry): once the analyzer toolchain no longer needs generic
-      // method comments, remove tests that exercise them.
-      fail('No generic method comment support in Fasta');
-    }
-    // Note: Fasta always supports lazy assignment operators (`&&=` and `||=`),
-    // so we can ignore the `lazyAssignmentOperators` flag.
-    // TODO(paulberry): once lazyAssignmentOperators are fully supported by
-    // Dart, remove this flag.
-    var scanner = new fasta.StringScanner(source, includeComments: true);
-    var token = scanner.tokenize();
-    var analyzerTokenHead = new Token(null, 0);
-    analyzerTokenHead.previous = analyzerTokenHead;
-    var analyzerTokenTail = analyzerTokenHead;
-    // TODO(paulberry,ahe): Fasta includes comments directly in the token
-    // stream, rather than pointing to them via a "precedingComment" pointer, as
-    // analyzer does.  This seems like it will complicate parsing and other
-    // operations.
-    CommentToken currentCommentHead;
-    CommentToken currentCommentTail;
-    while (true) {
-      if (scanner.hasErrors && token is fasta.ErrorToken) {
-        var error = _translateErrorToken(token, source.length);
-        if (error != null) {
-          listener.errors.add(error);
-        }
-      } else if (token is fasta.StringToken &&
-          token.info.kind == fasta.COMMENT_TOKEN) {
-        // TODO(paulberry,ahe): It would be nice if the scanner gave us an
-        // easier way to distinguish between the two types of comment.
-        var type = token.value.startsWith('/*')
-            ? TokenType.MULTI_LINE_COMMENT
-            : TokenType.SINGLE_LINE_COMMENT;
-        var translatedToken =
-            new CommentToken(type, token.value, token.charOffset);
-        if (currentCommentHead == null) {
-          currentCommentHead = currentCommentTail = translatedToken;
-        } else {
-          currentCommentTail.setNext(translatedToken);
-          currentCommentTail = translatedToken;
-        }
-      } else {
-        var translatedToken = _translateToken(token, currentCommentHead);
-        translatedToken.setNext(translatedToken);
-        currentCommentHead = currentCommentTail = null;
-        analyzerTokenTail.setNext(translatedToken);
-        translatedToken.previous = analyzerTokenTail;
-        analyzerTokenTail = translatedToken;
-      }
-      if (token.isEof) {
-        return analyzerTokenHead.next;
-      }
-      token = token.next;
-    }
-  }
-
-  _TestError _translateErrorToken(fasta.ErrorToken token, int inputLength) {
-    int charOffset = token.charOffset;
-    // TODO(paulberry,ahe): why is endOffset sometimes null?
-    int endOffset = token.endOffset ?? charOffset;
-    _TestError _makeError(ScannerErrorCode errorCode, List<Object> arguments) {
-      int errorLength = endOffset - charOffset;
-      if (charOffset == inputLength) {
-        // Analyzer never generates an error message past the end of the input,
-        // since such an error would not be visible in an editor.
-        // TODO(paulberry,ahe): would it make sense to replicate this behavior
-        // in fasta, or move it elsewhere in analyzer?
-        charOffset--;
-      }
-      if (errorLength == 0) {
-        // Analyzer never generates an error message of length zero,
-        // since such an error would not be visible in an editor.
-        // TODO(paulberry,ahe): would it make sense to replicate this behavior
-        // in fasta, or move it elsewhere in analyzer?
-        errorLength = 1;
-      }
-      return new _TestError(charOffset, errorLength, errorCode, arguments);
-    }
-
-    var errorCode = token.errorCode;
-    switch (errorCode) {
-      case fasta.ErrorKind.UnterminatedString:
-        // TODO(paulberry,ahe): Fasta reports the error location as the entire
-        // string; analyzer expects the end of the string.
-        charOffset = endOffset;
-        return _makeError(ScannerErrorCode.UNTERMINATED_STRING_LITERAL, null);
-      case fasta.ErrorKind.UnmatchedToken:
-        return null;
-      case fasta.ErrorKind.UnterminatedComment:
-        // TODO(paulberry,ahe): Fasta reports the error location as the entire
-        // comment; analyzer expects the end of the comment.
-        charOffset = endOffset;
-        return _makeError(
-            ScannerErrorCode.UNTERMINATED_MULTI_LINE_COMMENT, null);
-      case fasta.ErrorKind.MissingExponent:
-        // TODO(paulberry,ahe): Fasta reports the error location as the entire
-        // number; analyzer expects the end of the number.
-        charOffset = endOffset;
-        return _makeError(ScannerErrorCode.MISSING_DIGIT, null);
-      case fasta.ErrorKind.ExpectedHexDigit:
-        // TODO(paulberry,ahe): Fasta reports the error location as the entire
-        // number; analyzer expects the end of the number.
-        charOffset = endOffset;
-        return _makeError(ScannerErrorCode.MISSING_HEX_DIGIT, null);
-      case fasta.ErrorKind.NonAsciiIdentifier:
-      case fasta.ErrorKind.NonAsciiWhitespace:
-        return _makeError(
-            ScannerErrorCode.ILLEGAL_CHARACTER, [token.character]);
-      case fasta.ErrorKind.UnexpectedDollarInString:
-        return null;
-      default:
-        throw new UnimplementedError('$errorCode');
-    }
-  }
-
-  Keyword _translateKeyword(String syntax) =>
-      _keywordMap[syntax] ?? (throw new UnimplementedError('$syntax'));
-
-  Token _translateToken(fasta.Token token, CommentToken comment) {
-    var type = _translateTokenInfoKind(token.info.kind);
-    int offset = token.charOffset;
-    Token makeStringToken(String value) {
-      if (comment == null) {
-        return new StringToken(type, value, offset);
-      } else {
-        return new StringTokenWithComment(type, value, offset, comment);
-      }
-    }
-
-    Token makeKeywordToken(Keyword keyword) {
-      if (comment == null) {
-        return new KeywordToken(keyword, offset);
-      } else {
-        return new KeywordTokenWithComment(keyword, offset, comment);
-      }
-    }
-
-    Token makeBeginToken() {
-      if (comment == null) {
-        return new BeginToken(type, offset);
-      } else {
-        return new BeginTokenWithComment(type, offset, comment);
-      }
-    }
-
-    if (token is fasta.StringToken) {
-      return makeStringToken(token.value);
-    } else if (token is fasta.KeywordToken) {
-      return makeKeywordToken(_translateKeyword(token.keyword.syntax));
-    } else if (token is fasta.SymbolToken) {
-      if (token is fasta.BeginGroupToken) {
-        if (type == TokenType.LT) {
-          return makeStringToken(token.value);
-        } else {
-          return makeBeginToken();
-        }
-      } else {
-        return makeStringToken(token.value);
-      }
-    }
-    throw new UnimplementedError('${token.runtimeType}');
-  }
-
-  TokenType _translateTokenInfoKind(int kind) {
-    switch (kind) {
-      case fasta.EOF_TOKEN:
-        return TokenType.EOF;
-      case fasta.KEYWORD_TOKEN:
-        return TokenType.KEYWORD;
-      case fasta.IDENTIFIER_TOKEN:
-        return TokenType.IDENTIFIER;
-      case fasta.BAD_INPUT_TOKEN:
-        return TokenType.STRING;
-      case fasta.DOUBLE_TOKEN:
-        return TokenType.DOUBLE;
-      case fasta.INT_TOKEN:
-        return TokenType.INT;
-      case fasta.HEXADECIMAL_TOKEN:
-        return TokenType.HEXADECIMAL;
-      case fasta.STRING_TOKEN:
-        return TokenType.STRING;
-      case fasta.AMPERSAND_TOKEN:
-        return TokenType.AMPERSAND;
-      case fasta.BACKPING_TOKEN:
-        return TokenType.BACKPING;
-      case fasta.BACKSLASH_TOKEN:
-        return TokenType.BACKSLASH;
-      case fasta.BANG_TOKEN:
-        return TokenType.BANG;
-      case fasta.BAR_TOKEN:
-        return TokenType.BAR;
-      case fasta.COLON_TOKEN:
-        return TokenType.COLON;
-      case fasta.COMMA_TOKEN:
-        return TokenType.COMMA;
-      case fasta.EQ_TOKEN:
-        return TokenType.EQ;
-      case fasta.GT_TOKEN:
-        return TokenType.GT;
-      case fasta.HASH_TOKEN:
-        return TokenType.HASH;
-      case fasta.OPEN_CURLY_BRACKET_TOKEN:
-        return TokenType.OPEN_CURLY_BRACKET;
-      case fasta.OPEN_SQUARE_BRACKET_TOKEN:
-        return TokenType.OPEN_SQUARE_BRACKET;
-      case fasta.OPEN_PAREN_TOKEN:
-        return TokenType.OPEN_PAREN;
-      case fasta.LT_TOKEN:
-        return TokenType.LT;
-      case fasta.MINUS_TOKEN:
-        return TokenType.MINUS;
-      case fasta.PERIOD_TOKEN:
-        return TokenType.PERIOD;
-      case fasta.PLUS_TOKEN:
-        return TokenType.PLUS;
-      case fasta.QUESTION_TOKEN:
-        return TokenType.QUESTION;
-      case fasta.AT_TOKEN:
-        return TokenType.AT;
-      case fasta.CLOSE_CURLY_BRACKET_TOKEN:
-        return TokenType.CLOSE_CURLY_BRACKET;
-      case fasta.CLOSE_SQUARE_BRACKET_TOKEN:
-        return TokenType.CLOSE_SQUARE_BRACKET;
-      case fasta.CLOSE_PAREN_TOKEN:
-        return TokenType.CLOSE_PAREN;
-      case fasta.SEMICOLON_TOKEN:
-        return TokenType.SEMICOLON;
-      case fasta.SLASH_TOKEN:
-        return TokenType.SLASH;
-      case fasta.TILDE_TOKEN:
-        return TokenType.TILDE;
-      case fasta.STAR_TOKEN:
-        return TokenType.STAR;
-      case fasta.PERCENT_TOKEN:
-        return TokenType.PERCENT;
-      case fasta.CARET_TOKEN:
-        return TokenType.CARET;
-      case fasta.STRING_INTERPOLATION_TOKEN:
-        return TokenType.STRING_INTERPOLATION_EXPRESSION;
-      case fasta.LT_EQ_TOKEN:
-        return TokenType.LT_EQ;
-      case fasta.FUNCTION_TOKEN:
-        return TokenType.FUNCTION;
-      case fasta.SLASH_EQ_TOKEN:
-        return TokenType.SLASH_EQ;
-      case fasta.PERIOD_PERIOD_PERIOD_TOKEN:
-        return TokenType.PERIOD_PERIOD_PERIOD;
-      case fasta.PERIOD_PERIOD_TOKEN:
-        return TokenType.PERIOD_PERIOD;
-      case fasta.EQ_EQ_EQ_TOKEN:
-        // TODO(paulberry,ahe): what is this?
-        throw new UnimplementedError();
-      case fasta.EQ_EQ_TOKEN:
-        return TokenType.EQ_EQ;
-      case fasta.LT_LT_EQ_TOKEN:
-        return TokenType.LT_LT_EQ;
-      case fasta.LT_LT_TOKEN:
-        return TokenType.LT_LT;
-      case fasta.GT_EQ_TOKEN:
-        return TokenType.GT_EQ;
-      case fasta.GT_GT_EQ_TOKEN:
-        return TokenType.GT_GT_EQ;
-      case fasta.INDEX_EQ_TOKEN:
-        return TokenType.INDEX_EQ;
-      case fasta.INDEX_TOKEN:
-        return TokenType.INDEX;
-      case fasta.BANG_EQ_EQ_TOKEN:
-        // TODO(paulberry,ahe): what is this?
-        throw new UnimplementedError();
-      case fasta.BANG_EQ_TOKEN:
-        return TokenType.BANG_EQ;
-      case fasta.AMPERSAND_AMPERSAND_TOKEN:
-        return TokenType.AMPERSAND_AMPERSAND;
-      case fasta.AMPERSAND_EQ_TOKEN:
-        return TokenType.AMPERSAND_EQ;
-      case fasta.BAR_BAR_TOKEN:
-        return TokenType.BAR_BAR;
-      case fasta.BAR_EQ_TOKEN:
-        return TokenType.BAR_EQ;
-      case fasta.STAR_EQ_TOKEN:
-        return TokenType.STAR_EQ;
-      case fasta.PLUS_PLUS_TOKEN:
-        return TokenType.PLUS_PLUS;
-      case fasta.PLUS_EQ_TOKEN:
-        return TokenType.PLUS_EQ;
-      case fasta.MINUS_MINUS_TOKEN:
-        return TokenType.MINUS_MINUS;
-      case fasta.MINUS_EQ_TOKEN:
-        return TokenType.MINUS_EQ;
-      case fasta.TILDE_SLASH_EQ_TOKEN:
-        return TokenType.TILDE_SLASH_EQ;
-      case fasta.TILDE_SLASH_TOKEN:
-        return TokenType.TILDE_SLASH;
-      case fasta.PERCENT_EQ_TOKEN:
-        return TokenType.PERCENT_EQ;
-      case fasta.GT_GT_TOKEN:
-        return TokenType.GT_GT;
-      case fasta.CARET_EQ_TOKEN:
-        return TokenType.CARET_EQ;
-      case fasta.STRING_INTERPOLATION_IDENTIFIER_TOKEN:
-        return TokenType.STRING_INTERPOLATION_IDENTIFIER;
-      case fasta.QUESTION_PERIOD_TOKEN:
-        return TokenType.QUESTION_PERIOD;
-      case fasta.QUESTION_QUESTION_TOKEN:
-        return TokenType.QUESTION_QUESTION;
-      case fasta.QUESTION_QUESTION_EQ_TOKEN:
-        return TokenType.QUESTION_QUESTION_EQ;
-      default:
-        throw new UnimplementedError('$kind');
-    }
+  void test_incomplete_string_interpolation() {
+    super.test_incomplete_string_interpolation();
   }
 }
 
 abstract class ScannerTestBase {
+  Token scanWithListener(String source, ErrorListener listener,
+      {bool genericMethodComments: false, bool lazyAssignmentOperators: false});
+
   void test_ampersand() {
     _assertToken(TokenType.AMPERSAND, "&");
   }
@@ -788,7 +291,7 @@ abstract class ScannerTestBase {
  * bbb
  * c
  */''';
-    _ErrorListener listener = new _ErrorListener();
+    ErrorListener listener = new ErrorListener();
     Scanner scanner = new _TestScanner(new CharSequenceReader(code), listener);
     scanner.tokenize();
     expect(
@@ -1252,7 +755,7 @@ abstract class ScannerTestBase {
 
   void test_setSourceStart() {
     int offsetDelta = 42;
-    _ErrorListener listener = new _ErrorListener();
+    ErrorListener listener = new ErrorListener();
     Scanner scanner =
         new _TestScanner(new SubSequenceReader("a", offsetDelta), listener);
     scanner.setSourceStart(3, 9);
@@ -1523,8 +1026,8 @@ abstract class ScannerTestBase {
   }
 
   void test_unclosedPairInInterpolation() {
-    _ErrorListener listener = new _ErrorListener();
-    _scanWithListener("'\${(}'", listener);
+    ErrorListener listener = new ErrorListener();
+    scanWithListener("'\${(}'", listener);
   }
 
   void _assertComment(TokenType commentType, String source,
@@ -1566,10 +1069,10 @@ abstract class ScannerTestBase {
   void _assertError(
       ScannerErrorCode expectedError, int expectedOffset, String source,
       [List<Object> arguments]) {
-    _ErrorListener listener = new _ErrorListener();
-    _scanWithListener(source, listener);
+    ErrorListener listener = new ErrorListener();
+    scanWithListener(source, listener);
     listener.assertErrors(
-        [new _TestError(expectedOffset, 1, expectedError, arguments)]);
+        [new TestError(expectedOffset, 1, expectedError, arguments)]);
   }
 
   /**
@@ -1583,10 +1086,10 @@ abstract class ScannerTestBase {
    */
   void _assertErrorAndTokens(ScannerErrorCode expectedError, int expectedOffset,
       String source, List<Token> expectedTokens) {
-    _ErrorListener listener = new _ErrorListener();
-    Token token = _scanWithListener(source, listener);
+    ErrorListener listener = new ErrorListener();
+    Token token = scanWithListener(source, listener);
     listener
-        .assertErrors([new _TestError(expectedOffset, 1, expectedError, null)]);
+        .assertErrors([new TestError(expectedOffset, 1, expectedError, null)]);
     _checkTokens(token, expectedTokens);
   }
 
@@ -1701,16 +1204,57 @@ abstract class ScannerTestBase {
   Token _scan(String source,
       {bool genericMethodComments: false,
       bool lazyAssignmentOperators: false}) {
-    _ErrorListener listener = new _ErrorListener();
-    Token token = _scanWithListener(source, listener,
+    ErrorListener listener = new ErrorListener();
+    Token token = scanWithListener(source, listener,
         genericMethodComments: genericMethodComments,
         lazyAssignmentOperators: lazyAssignmentOperators);
     listener.assertNoErrors();
     return token;
   }
+}
+
+class TestError {
+  final int offset;
+  final int length;
+  final ErrorCode errorCode;
+  final List<Object> arguments;
+
+  TestError(this.offset, this.length, this.errorCode, this.arguments);
+
+  @override
+  get hashCode {
+    var h = new JenkinsSmiHash()..add(offset)..add(length)..add(errorCode);
+    if (arguments != null) {
+      for (Object argument in arguments) {
+        h.add(argument);
+      }
+    }
+    return h.hashCode;
+  }
 
-  Token _scanWithListener(String source, _ErrorListener listener,
-      {bool genericMethodComments: false, bool lazyAssignmentOperators: false});
+  @override
+  operator ==(Object other) {
+    if (other is TestError &&
+        offset == other.offset &&
+        length == other.length &&
+        errorCode == other.errorCode) {
+      if (arguments == null) return other.arguments == null;
+      if (other.arguments == null) return false;
+      if (arguments.length != other.arguments.length) return false;
+      for (int i = 0; i < arguments.length; i++) {
+        if (arguments[i] != other.arguments[i]) return false;
+      }
+      return true;
+    }
+    return false;
+  }
+
+  @override
+  toString() {
+    var end = offset + length;
+    var argString = arguments == null ? '' : '(${arguments.join(', ')})';
+    return 'Error($offset..$end, $errorCode$argString)';
+  }
 }
 
 @reflectiveTest
@@ -1781,64 +1325,8 @@ class TokenTypeTest {
   }
 }
 
-class _ErrorListener {
-  final errors = <_TestError>[];
-
-  void assertErrors(List<_TestError> expectedErrors) {
-    expect(errors, unorderedEquals(expectedErrors));
-  }
-
-  void assertNoErrors() {
-    assertErrors([]);
-  }
-}
-
-class _TestError {
-  final int offset;
-  final int length;
-  final ErrorCode errorCode;
-  final List<Object> arguments;
-
-  _TestError(this.offset, this.length, this.errorCode, this.arguments);
-
-  @override
-  get hashCode {
-    var h = new JenkinsSmiHash()..add(offset)..add(length)..add(errorCode);
-    if (arguments != null) {
-      for (Object argument in arguments) {
-        h.add(argument);
-      }
-    }
-    return h.hashCode;
-  }
-
-  @override
-  operator ==(Object other) {
-    if (other is _TestError &&
-        offset == other.offset &&
-        length == other.length &&
-        errorCode == other.errorCode) {
-      if (arguments == null) return other.arguments == null;
-      if (other.arguments == null) return false;
-      if (arguments.length != other.arguments.length) return false;
-      for (int i = 0; i < arguments.length; i++) {
-        if (arguments[i] != other.arguments[i]) return false;
-      }
-      return true;
-    }
-    return false;
-  }
-
-  @override
-  toString() {
-    var end = offset + length;
-    var argString = arguments == null ? '' : '(${arguments.join(', ')})';
-    return 'Error($offset..$end, $errorCode$argString)';
-  }
-}
-
 class _TestScanner extends Scanner {
-  final _ErrorListener listener;
+  final ErrorListener listener;
 
   _TestScanner(CharacterReader reader, [this.listener]) : super(reader);
 
@@ -1846,7 +1334,7 @@ class _TestScanner extends Scanner {
   void reportError(
       ScannerErrorCode errorCode, int offset, List<Object> arguments) {
     if (listener != null) {
-      listener.errors.add(new _TestError(offset, 1, errorCode, arguments));
+      listener.errors.add(new TestError(offset, 1, errorCode, arguments));
     }
   }
 }