[pygobject/wip/jfelder/gdk4-release-mask] tests: GDK_RELEASE_MASK has been removed from GTK4

[Jean Felder <jfelder src gnome org>]

commit c86b0830516651a1a9c28dbe35d7a028d690696c
Author: Jean Felder <jean felder gmail com>
Date:   Fri Apr 17 14:37:57 2020 +0200

    tests: GDK_RELEASE_MASK has been removed from GTK4
    
    See gtk commit 2244eeb7270f5a0b351aae98c19ddbc4d4b5bea7.

 tests/test_overrides_gdk.py | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)
---
diff --git a/tests/test_overrides_gdk.py b/tests/test_overrides_gdk.py
index e809da07..d49cdcf3 100644
--- a/tests/test_overrides_gdk.py
+++ b/tests/test_overrides_gdk.py
@@ -247,14 +247,16 @@ class TestGdk(unittest.TestCase):
         self.assertEqual(str(Gdk.ModifierType.META_MASK),
                          '<flags GDK_META_MASK of type Gdk.ModifierType>')
 
-        self.assertEqual(Gdk.ModifierType.RELEASE_MASK | 0, 0x40000000)
-        self.assertEqual(hex(Gdk.ModifierType.RELEASE_MASK), '0x40000000')
-        self.assertEqual(str(Gdk.ModifierType.RELEASE_MASK),
-                         '<flags GDK_RELEASE_MASK of type Gdk.ModifierType>')
-
-        self.assertEqual(Gdk.ModifierType.RELEASE_MASK | Gdk.ModifierType.META_MASK, 0x50000000)
-        self.assertEqual(str(Gdk.ModifierType.RELEASE_MASK | Gdk.ModifierType.META_MASK),
-                         '<flags GDK_META_MASK | GDK_RELEASE_MASK of type Gdk.ModifierType>')
+        # RELEASE_MASK does not exist in gdk4
+        if not GDK4:
+            self.assertEqual(Gdk.ModifierType.RELEASE_MASK | 0, 0x40000000)
+            self.assertEqual(hex(Gdk.ModifierType.RELEASE_MASK), '0x40000000')
+            self.assertEqual(str(Gdk.ModifierType.RELEASE_MASK),
+                             '<flags GDK_RELEASE_MASK of type Gdk.ModifierType>')
+
+            self.assertEqual(Gdk.ModifierType.RELEASE_MASK | Gdk.ModifierType.META_MASK, 0x50000000)
+            self.assertEqual(str(Gdk.ModifierType.RELEASE_MASK | Gdk.ModifierType.META_MASK),
+                             '<flags GDK_META_MASK | GDK_RELEASE_MASK of type Gdk.ModifierType>')
 
     @unittest.skipIf(GDK4, "not in gdk4")
     def test_color_parse(self):