Strings recipes for the Dart Cookbook

recipes/test/core/strings/handling_extended_characters_test.dart

Index: recipes/test/core/strings/handling_extended_characters_test.dart
diff --git a/recipes/test/core/strings/handling_extended_characters_test.dart b/recipes/test/core/strings/handling_extended_characters_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..385135cabd49a929bc7c5c50a9bcf33077bd1187
--- /dev/null
+++ b/recipes/test/core/strings/handling_extended_characters_test.dart
@@ -0,0 +1,41 @@
+library handling_extended_characters_test;
+
+import 'package:unittest/unittest.dart';
+
+print(obj) => obj;
+
+void main() {
+  var clef = '\u{1F3BC}';
+  group('creating an extended character', () {
+    test('using a rune', () {
+      expect(print(clef), equals('🎼'));
+    });
+  });
+  
+  group('accessing runes and code units', () {
+    test('', () {
+      expect(clef.codeUnits.map((codeUnit) => codeUnit.toRadixString(16)), equals(['d83c', 'dfbc']));
+      expect(clef.runes.map((rune) => rune.toRadixString(16)).toList(), equals(['1f3bc']));
+    });
+  });
+  
+  group('accessing length', () {
+    test('', () {
+      expect(print(clef.length), equals(2));
+      expect(print(clef.codeUnits.length), equals(2));
+      expect(print(clef.runes.length), equals(1));
+    });
+  });
+  
+  group('subscripting', () {
+    test('', () {
+      expect(print(clef.runes.first.toRadixString(16)), equals('1f3bc'));
+      expect(print(clef.runes.toList()[0].toRadixString(16)), equals('1f3bc'));
+      // This test will never pass because clef[0] is an illegal string.
+      // expect(print(clef[0]), equals('?'));
+      expect(print(clef.codeUnits[0]), equals(55356));
+      expect(clef.runes.toList()[0], equals(127932));
+    });
+  });
+}
+