Strings recipes for the Dart Cookbook

recipes/test/core/strings/converting_chars_nums_test.dart

Index: recipes/test/core/strings/converting_chars_nums_test.dart
diff --git a/recipes/test/core/strings/converting_chars_nums_test.dart b/recipes/test/core/strings/converting_chars_nums_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..482a909f3808e36f22d1c0023602ae0fbf9db98f
--- /dev/null
+++ b/recipes/test/core/strings/converting_chars_nums_test.dart
@@ -0,0 +1,73 @@
+library converting_chars_nums_test;
+
+import 'package:unittest/unittest.dart';
+
+
+void main() {
+  group('converting between string characters and numerical codes', () {
+    var smileyFace = '\u263A';
+    var clef = '\u{1F3BC}';
+    
+    group('using runes', () {
+      test('', () {
+        expect('Dart'.runes.toList(), equals([68, 97, 114, 116]));
+        
+        var codePoints = smileyFace.runes.toList(); // [9786]
+        expect(codePoints.first.toRadixString(16), equals('263a'));
+        
+        codePoints = clef.runes.toList(); // [127932]
+        expect(codePoints.first.toRadixString(16), equals('1f3bc'));
+      });
+    });
+    
+    group('using codeUnits', () {
+      test('', () {
+        expect('Dart'.codeUnits.toList(), equals([68, 97, 114, 116]));
+
+        var codeUnits = smileyFace.codeUnits.toList(); // [9786]
+        expect(codeUnits.first.toRadixString(16), equals('263a'));
+        
+        codeUnits = clef.codeUnits.toList(); // [55356, 57276]
+        expect(codeUnits.map((codeUnit) => codeUnit.toRadixString(16)).toList(), equals(['d83c', 'dfbc']));
+      });
+    });
+    
+    group('using codeUnitAt', () {
+      test('', () {
+        expect('Dart'.codeUnitAt(0), equals(68));
+        
+        var codeUnit = smileyFace.codeUnitAt(0); // 9786
+        expect(codeUnit.toRadixString(16), equals('263a'));
+        
+        codeUnit = clef.codeUnitAt(0); // 55356
+        expect(codeUnit.toRadixString(16), equals('d83c'));
+        
+        codeUnit = clef.codeUnitAt(1); // 57276
+        expect(codeUnit.toRadixString(16), equals('dfbc'));
+      });
+    });
+ 
+    group('using fromCharCodes', () {
+      var heart = '\u2661';
+      
+      test('', () {
+        expect(new String.fromCharCodes([68, 97, 114, 116]), equals('Dart'));
+        expect(new String.fromCharCodes([73, 32, 9825, 32, 76, 117, 99, 121]),
+            equals("I $heart Lucy"));
+      });
+      
+      var smileyFace = '\u263A';
+      test('', () {
+        expect(new String.fromCharCodes([9786]), equals(smileyFace));
+      });
+      
+      test('with surrogate pair codeUnits', () {
+        expect(new String.fromCharCodes([55356, 57276]), equals(clef));
+      });
+      
+      test('with rune', () {
+        expect(new String.fromCharCode(127932), equals(clef));
+      });
+    });
+  });
+}