[pygobject] Gio.Settings: implement __iter__

[Christoph Reiter <creiter src gnome org>]

commit c1da8edf4d18b6a1fa17ca55f4163af44ea95bbb
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Tue Apr 17 12:24:11 2018 +0200

    Gio.Settings: implement __iter__
    
    It defaults to __len__ and __getitem__ otherwise which fails because
    we work with keys and not indices.

 gi/overrides/Gio.py | 4 ++++
 tests/test_gio.py   | 5 +++++
 2 files changed, 9 insertions(+)
---
diff --git a/gi/overrides/Gio.py b/gi/overrides/Gio.py
index 8604d550..3cdc7b18 100644
--- a/gi/overrides/Gio.py
+++ b/gi/overrides/Gio.py
@@ -105,6 +105,10 @@ class Settings(Gio.Settings):
     def __len__(self):
         return len(self.list_keys())
 
+    def __iter__(self):
+        for key in self.list_keys():
+            yield key
+
     def __bool__(self):
         # for "if mysettings" we don't want a dictionary-like test here, just
         # if the object isn't None
diff --git a/tests/test_gio.py b/tests/test_gio.py
index 92159c17..6ad5b116 100644
--- a/tests/test_gio.py
+++ b/tests/test_gio.py
@@ -64,6 +64,11 @@ class TestGSettings(unittest.TestCase):
         self.settings.reset('test-boolean')
         self.settings.reset('test-enum')
 
+    def test_iter(self):
+        assert list(self.settings) == [
+            'test-tuple', 'test-array', 'test-boolean', 'test-string',
+            'test-enum']
+
     def test_native(self):
         self.assertTrue('test-array' in self.settings.list_keys())