Strings recipes for the Dart Cookbook

recipes/test/core/strings/processing_a_string_one_character_test.dart

Index: recipes/test/core/strings/processing_a_string_one_character_test.dart
diff --git a/recipes/test/core/strings/processing_a_string_one_character_test.dart b/recipes/test/core/strings/processing_a_string_one_character_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..ac000d04717fec9ea16d19a706519af47a040236
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+++ b/recipes/test/core/strings/processing_a_string_one_character_test.dart
@@ -0,0 +1,62 @@
+library processing_a_string_one_character_test;
+
+import 'package:unittest/unittest.dart';
+
+print(obj) {
+  return obj;
+}
+
+void main() {
+  
+  group('processing a string one character at a time', () {
+    var clef = '\u{1F3BC}';
+    var lang= 'Dart';
+    
+    group('using split', () {
+      test('on code-unit boundary', () {
+        expect(lang.split('').map((char) => '*${char}*').toList(),
+            equals(['*D*', '*a*', '*r*', '*t*']));
+        
+        var smileyFace = '\u263A';
+        var happy = 'I am $smileyFace';
+        expect(print(happy.split('')), equals(['I', ' ', 'a', 'm', ' ', '☺']));
+        expect(clef.split('').length, equals(2));
+      });
+    });
+    
+    group('indexing the string in a loop', () {
+      test('', () {
+        var list = [];
+        for(var i = 0; i < lang.length; i++) {
+          list.add('*${lang[i]}*'); 
+        }
+        expect(list, equals(['*D*', '*a*', '*r*', '*t*']));      
+      });
+      
+      test('with an extended character', () {
+        var list = [];
+        for(var i = 0; i < clef.length; i++) {
+          list.add([clef[i], clef[i].runes.first]); 
+        }
+        // Because we are dealing with invalid strings, this test can never pass.
+        // expect(print(list.last), equals([[?, 55356], [?, 57276]]));
+      });
+    });
+
+    group('mapping runes', () {
+      test('', () {
+        expect(lang.runes.map((rune) => '*${new String.fromCharCode(rune)}*').toList(),
+            equals(['*D*', '*a*', '*r*', '*t*']));
+        
+        var smileyFace = '\u263A';
+        var happy = 'I am $smileyFace';
+        expect(happy.runes.map((rune) => [rune, new String.fromCharCode(rune)]).toList(), 
+            equals([ [73, 'I'], [32, ' '], [97, 'a'], [109, 'm'], [32, ' '], [9786, '☺'] ]));
+        
+        var subject = '$clef list:';
+        expect(subject.runes.map((rune) => new String.fromCharCode(rune)).toList(), 
+            equals(['🎼', ' ', 'l', 'i', 's', 't', ':']));
+      });
+    });
+  });
+}