Extract 'computeLineStarts' utility.

pkg/analyzer/test/generated/utilities_test.dart

 // Copyright (c) 2014, 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.
 
 library engine.utilities_test;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/java_core.dart';
@@ skipping 4548 matching lines @@
   }
 
   void test_toString() {
     SourceRange r = new SourceRange(10, 1);
     expect(r.toString(), "[offset=10, length=1]");
   }
 }
 
 @reflectiveTest
 class StringUtilitiesTest {
+  void test_computeLineStarts_n() {
+    List<int> starts = StringUtilities.computeLineStarts('a\nbb\nccc');
+    expect(starts, <int>[0, 2, 5]);
+  }
+
+  void test_computeLineStarts_r() {
+    List<int> starts = StringUtilities.computeLineStarts('a\rbb\rccc');
+    expect(starts, <int>[0, 2, 5]);
+  }
+
+  void test_computeLineStarts_rn() {
+    List<int> starts = StringUtilities.computeLineStarts('a\r\nbb\r\nccc');
+    expect(starts, <int>[0, 3, 7]);
+  }
+
   void test_EMPTY() {
     expect(StringUtilities.EMPTY, "");
     expect(StringUtilities.EMPTY.isEmpty, isTrue);
   }
 
   void test_EMPTY_ARRAY() {
     expect(StringUtilities.EMPTY_ARRAY.length, 0);
   }
 
   void test_endsWith3() {
@@ skipping 249 matching lines @@
   }
 
   void test_get_added() {
     TokenMap tokenMap = new TokenMap();
     Token key = TokenFactory.tokenFromType(TokenType.AT);
     Token value = TokenFactory.tokenFromType(TokenType.AT);
     tokenMap.put(key, value);
     expect(tokenMap.get(key), same(value));
   }
 }