Add StringScanner.scanChar() and .expectChar().

test/string_scanner_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.
 
+import 'package:charcode/charcode.dart';
 import 'package:string_scanner/string_scanner.dart';
 import 'package:test/test.dart';
 
 void main() {
   group('with an empty string', () {
     var scanner;
     setUp(() {
       scanner = new StringScanner('');
     });
 
@@ skipping 19 matching lines @@
       expect(scanner.lastMatch, isNull);
       expect(scanner.position, equals(0));
     });
 
     test("peekChar returns null and doesn't change the state", () {
       expect(scanner.peekChar(), isNull);
       expect(scanner.lastMatch, isNull);
       expect(scanner.position, equals(0));
     });
 
+    test("scanChar returns false and doesn't change the state", () {
+      expect(scanner.scanChar($f), isFalse);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(0));
+    });
+
+    test("expectChar fails and doesn't change the state", () {
+      expect(() => scanner.expectChar($f), throwsFormatException);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(0));
+    });
+
     test("scan returns false and doesn't change the state", () {
       expect(scanner.scan(new RegExp('.')), isFalse);
       expect(scanner.lastMatch, isNull);
       expect(scanner.position, equals(0));
     });
 
     test("expect throws a FormatException and doesn't change the state", () {
       expect(() => scanner.expect(new RegExp('.')), throwsFormatException);
       expect(scanner.lastMatch, isNull);
       expect(scanner.position, equals(0));
@@ skipping 56 matching lines @@
       expect(scanner.lastMatch, isNull);
       expect(scanner.position, equals(0));
     });
 
     test('peekChar with an argument returns the nth character', () {
       expect(scanner.peekChar(4), equals(0x62));
       expect(scanner.lastMatch, isNull);
       expect(scanner.position, equals(0));
     });
 
+    test("a matching scanChar returns true moves forward", () {
+      expect(scanner.scanChar($f), isTrue);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(1));
+    });
+
+    test("a non-matching scanChar returns false and does nothing", () {
+      expect(scanner.scanChar($x), isFalse);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(0));
+    });
+
+    test("a matching expectChar moves forward", () {
+      scanner.expectChar($f);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(1));
+    });
+
+    test("a non-matching expectChar fails", () {
+      expect(() => scanner.expectChar($x), throwsFormatException);
+      expect(scanner.lastMatch, isNull);
+      expect(scanner.position, equals(0));
+    });
+
     test("a matching scan returns true and changes the state", () {
       expect(scanner.scan(new RegExp('f(..)')), isTrue);
       expect(scanner.lastMatch[1], equals('oo'));
       expect(scanner.position, equals(3));
       expect(scanner.rest, equals(' bar'));
     });
 
     test("a non-matching scan returns false and sets lastMatch to null", () {
       expect(scanner.matches(new RegExp('f(..)')), isTrue);
       expect(scanner.lastMatch, isNotNull);
@@ skipping 119 matching lines @@
       expect(scanner.lastMatch, isNotNull);
       expect(scanner.position, equals(7));
     });
 
     test("peekChar returns null and doesn't change the state", () {
       expect(scanner.peekChar(), isNull);
       expect(scanner.lastMatch, isNotNull);
       expect(scanner.position, equals(7));
     });
 
+    test("scanChar returns false and doesn't change the state", () {
+      expect(scanner.scanChar($f), isFalse);
+      expect(scanner.lastMatch, isNotNull);
+      expect(scanner.position, equals(7));
+    });
+
+    test("expectChar fails and doesn't change the state", () {
+      expect(() => scanner.expectChar($f), throwsFormatException);
+      expect(scanner.lastMatch, isNotNull);
+      expect(scanner.position, equals(7));
+    });
+
     test("scan returns false and sets lastMatch to null", () {
       expect(scanner.scan(new RegExp('.')), isFalse);
       expect(scanner.lastMatch, isNull);
       expect(scanner.position, equals(7));
     });
 
     test("expect throws a FormatException and sets lastMatch to null", () {
       expect(() => scanner.expect(new RegExp('.')), throwsFormatException);
       expect(scanner.lastMatch, isNull);
       expect(scanner.position, equals(7));
@@ skipping 57 matching lines @@
       expect(() => new StringScanner('foo bar', position: -1),
           throwsArgumentError);
     });
 
     test('throws an ArgumentError if the position is beyond the string', () {
       expect(
           () => new StringScanner('foo bar', position: 8), throwsArgumentError);
     });
   });
 }