Capitalized Method (#51)

* Added upperCaseFirst method.

* Added tests.

* Fixed the format.

* Simplified.

* Remove unecessary method and test for nullables.

* Improved the format.

* Changed the name of the method and improved the code.

* Added testing of non ASCII first character and updated the tests and docstring.

* Fixed the format.

* Added empty line.

* renamed the method.

* Code clean-up.

* renamed.

Author: arielmagbanua

lib/string_basics.dart

@@ -200,6 +200,42 @@ extension StringBasics on String {
     }
     return stringBuffer.toString();
   }
+
+  /// Returns a string with the first character in upper case.
+  ///
+  /// This method can capitalize first character
+  /// that is either alphabetic or accented.
+  ///
+  /// If the first character is not alphabetic then return the same string.
+  /// If [this] is empty, returns and empty string.
+  ///
+  /// Example:
+  /// ```dart
+  /// final foo = 'bar';
+  /// final baz = foo.capitalizeFirst(); // 'Bar'
+  ///
+  /// // accented first character
+  /// final og = 'éfoo';
+  /// final capitalized = og.capitalizeFirst() // 'Éfoo'
+  ///
+  /// // non alphabetic first character
+  /// final foo1 = '1bar';
+  /// final baz1 = foo1.capitalizeFirst(); // '1bar'
+  ///
+  /// final test = '';
+  /// final result = test.capitalizeFirst(); // ''
+  /// ```
+  String capitalize() {
+    if (this.isEmpty) return '';
+
+    // trim this string first
+    final trimmed = this.trimLeft();
+
+    // convert the first character to upper case
+    final firstCharacter = trimmed[0].toUpperCase();
+
+    return trimmed.replaceRange(0, 1, firstCharacter);
+  }
 }
 
 extension NullableStringBasics on String? {

test/string_basics_test.dart

@@ -352,4 +352,30 @@ void main() {
       expect('a'.isNotNullOrBlank, isTrue);
     });
   });
+
+  group('capitalize', () {
+    test('returns a new string with the first character in upper case', () {
+      expect('foo'.capitalize(), 'Foo');
+      expect('hello World'.capitalize(), 'Hello World');
+    });
+
+    test(
+        'returns a new string with the first non-ASCII unicode character'
+        'or accented characters in upper case', () {
+      expect('éfoo'.capitalize(), 'Éfoo');
+    });
+
+    test(
+        'returns same string if the first character is not an'
+        'alphabet character', () {
+      expect('1bravo'.capitalize(), '1bravo');
+      expect('2nd'.capitalize(), '2nd');
+      expect('ßfoo'.capitalize(), 'ßfoo');
+      expect('文foo'.capitalize(), '文foo');
+    });
+
+    test('returns empty if the string is empty', () {
+      expect(''.capitalize(), '');
+    });
+  });
 }