Enforce token syntax for CssClassSet arguments

tests/html/element_classes_test.dart

 // Copyright (c) 2011, 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 ElementTest;
 import 'package:unittest/unittest.dart';
 import 'package:unittest/html_config.dart';
 import 'dart:collection';
 import 'dart:html';
 
@@ skipping 111 matching lines @@
   test('length', () {
     expect(makeClassSet().length, 3);
     expect(makeElement().classes.length, 0);
   });
 
   test('contains', () {
     expect(makeClassSet().contains('foo'), isTrue);
     expect(makeClassSet().contains('qux'), isFalse);
   });
 
+  test('contains-bad', () {
+    // Non-strings return `false`.
+    // Strings need to be valid tokens.
+    final classes = makeClassSet();
+    expect(classes.contains(1), isFalse);
+    expect(() => classes.contains(''), throws);
+    expect(() => classes.contains('foo bar'), throws);
+  });
+
   test('add', () {
     final classes = makeClassSet();
     var added = classes.add('qux');
     expect(added, isTrue);
     expect(classes, orderedEquals(['foo', 'bar', 'baz', 'qux']));
 
     added = classes.add('qux');
     expect(added, isFalse);
     final list = new List.from(classes);
     list.sort((a, b) => a.compareTo(b));
     expect(list, orderedEquals(['bar', 'baz', 'foo', 'qux']),
         reason: "The class set shouldn't have duplicate elements.");
   });
 
+  test('add-bad', () {
+    final classes = makeClassSet();
+    expect(() => classes.add(''), throws);
+    expect(() => classes.add('foo bar'), throws);
+  });
+
   test('remove', () {
     final classes = makeClassSet();
     classes.remove('bar');
     expect(classes, orderedEquals(['foo', 'baz']));
     classes.remove('qux');
     expect(classes, orderedEquals(['foo', 'baz']));
   });
 
+  test('remove-bad', () {
+    final classes = makeClassSet();
+    expect(() => classes.remove(''), throws);
+    expect(() => classes.remove('foo bar'), throws);
+  });
+
   test('toggle', () {
     final classes = makeClassSet();
     classes.toggle('bar');
     expect(classes, orderedEquals(['foo', 'baz']));
     classes.toggle('qux');
     expect(classes, orderedEquals(['foo', 'baz', 'qux']));
 
     classes.toggle('qux', true);
     expect(classes, orderedEquals(['foo', 'baz', 'qux']));
     classes.toggle('qux', false);
     expect(classes, orderedEquals(['foo', 'baz']));
     classes.toggle('qux', false);
     expect(classes, orderedEquals(['foo', 'baz']));
     classes.toggle('qux', true);
     expect(classes, orderedEquals(['foo', 'baz', 'qux']));
   });
 
+  test('toggle-bad', () {
+    final classes = makeClassSet();
+    expect(() => classes.toggle(''), throws);
+    expect(() => classes.toggle('', true), throws);
+    expect(() => classes.toggle('', false), throws);
+    expect(() => classes.toggle('foo bar'), throws);
+    expect(() => classes.toggle('foo bar', true), throws);
+    expect(() => classes.toggle('foo bar', false), throws);
+  });
+
   test('addAll', () {
     final classes = makeClassSet();
     classes.addAll(['bar', 'qux', 'bip']);
     expect(classes, orderedEquals(['foo', 'bar', 'baz', 'qux', 'bip']));
   });
 
   test('removeAll', () {
     final classes = makeClassSet();
     classes.removeAll(['bar', 'baz', 'qux']);
     expect(classes, orderedEquals(['foo']));
@@ skipping 176 matching lines @@
     expect(view(elements.classes), '[quux, qux]');
     expect(view(elements), '[[quux, qux], [], [], [qux]]');
   });
 
   test('listContainsAll', () {
     var elements = listElementSetup();
     expect(elements.classes.containsAll(['qux', 'meta', 'mornin']), isFalse);
     expect(elements.classes.containsAll(['qux', 'lassy', 'classy']), isTrue);
   });
 }