[shared_preferences] Add containsKey method (flutter#1373)

ivk1800 · collinjackson · commit ba47d2397b2f · 2019-04-09T08:26:59.000-07:00
diff --git a/packages/shared_preferences/CHANGELOG.md b/packages/shared_preferences/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.5.2
+
+* Add containsKey method.
+
 ## 0.5.1+2
 
 * Add a driver test
diff --git a/packages/shared_preferences/lib/shared_preferences.dart b/packages/shared_preferences/lib/shared_preferences.dart
@@ -70,6 +70,9 @@ class SharedPreferences {
   /// String.
   String getString(String key) => _preferenceCache[key];
 
+  /// Returns true if persistent storage the contains the given [key].
+  bool containsKey(String key) => _preferenceCache.containsKey(key);
+
   /// Reads a set of string values from persistent storage, throwing an
   /// exception if it's not a string set.
   List<String> getStringList(String key) {
diff --git a/packages/shared_preferences/pubspec.yaml b/packages/shared_preferences/pubspec.yaml
@@ -3,7 +3,7 @@ description: Flutter plugin for reading and writing simple key-value pairs.
   Wraps NSUserDefaults on iOS and SharedPreferences on Android.
 author: Flutter Team <flutter-dev@googlegroups.com>
 homepage: https://github.com/flutter/plugins/tree/master/packages/shared_preferences
-version: 0.5.1+2
+version: 0.5.2
 
 flutter:
   plugin:
diff --git a/packages/shared_preferences/test/shared_preferences_test.dart b/packages/shared_preferences/test/shared_preferences_test.dart
@@ -125,6 +125,15 @@ void main() {
           ));
     });
 
+    test('containsKey', () async {
+      const String key = 'testKey';
+
+      expect(false, preferences.containsKey(key));
+
+      preferences.setString(key, 'test');
+      expect(true, preferences.containsKey(key));
+    });
+
     test('clearing', () async {
       await preferences.clear();
       expect(preferences.getString('String'), null);
