[pygobject] Variant.keys: correctly raise TypeError for non-dict types

[Christoph Reiter <creiter src gnome org>]

commit 66161778dfac3ad7a075a22052482c7593efe0bc
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Wed Nov 21 23:26:39 2018 +0100

    Variant.keys: correctly raise TypeError for non-dict types
    
    It was returning instead of raising the error for some reason.

 gi/overrides/GLib.py         | 2 +-
 tests/test_overrides_glib.py | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)
---
diff --git a/gi/overrides/GLib.py b/gi/overrides/GLib.py
index 97bdfc1c..650d6bd8 100644
--- a/gi/overrides/GLib.py
+++ b/gi/overrides/GLib.py
@@ -392,7 +392,7 @@ class Variant(GLib.Variant):
 
     def keys(self):
         if not self.get_type_string().startswith('a{'):
-            return TypeError, 'GVariant type %s is not a dictionary' % self.get_type_string()
+            raise TypeError('GVariant type %s is not a dictionary' % self.get_type_string())
 
         res = []
         for i in range(self.n_children()):
diff --git a/tests/test_overrides_glib.py b/tests/test_overrides_glib.py
index 947c74bf..82a2608d 100644
--- a/tests/test_overrides_glib.py
+++ b/tests/test_overrides_glib.py
@@ -143,6 +143,9 @@ class TestGVariant(unittest.TestCase):
         with pytest.raises(TypeError):
             variant[0]
 
+        with pytest.raises(TypeError):
+            variant.keys()
+
     def test_create_variant(self):
         variant = GLib.Variant('v', GLib.Variant('i', 42))
         self.assertTrue(isinstance(variant, GLib.Variant))