Add a binding test involving interfaces

This tests the new functionality that
g_type_interface_instantiable_prerequisite
was added for.

Before the changes, this fails with
GObject-WARNING **: Unable to convert a value of type \
                    GObject to a value of type Foo

We do the same test with g_object_bind_property_with_closures
as well, to exercise g_cclosure_marshal_generic.

gobject/tests/binding.c

@@ -2,6 +2,47 @@
 #include <gstdio.h>
 #include <glib-object.h>
 
+typedef struct {
+  GTypeInterface g_iface;
+} FooInterface;
+
+GType foo_get_type (void);
+
+G_DEFINE_INTERFACE (Foo, foo, G_TYPE_OBJECT)
+
+static void
+foo_default_init (FooInterface *iface)
+{
+}
+
+typedef struct {
+  GObject parent;
+} Baa;
+
+typedef struct {
+  GObjectClass parent_class;
+} BaaClass;
+
+static void
+baa_init_foo (FooInterface *iface)
+{
+}
+
+GType baa_get_type (void);
+
+G_DEFINE_TYPE_WITH_CODE (Baa, baa, G_TYPE_OBJECT,
+                         G_IMPLEMENT_INTERFACE (foo_get_type (), baa_init_foo))
+
+static void
+baa_init (Baa *baa)
+{
+}
+
+static void
+baa_class_init (BaaClass *class)
+{
+}
+
 typedef struct _BindingSource
 {
   GObject parent_instance;
@@ -10,6 +51,7 @@ typedef struct _BindingSource
   gint bar;
   gdouble double_value;
   gboolean toggle;
+  gpointer item;
 } BindingSource;
 
 typedef struct _BindingSourceClass
@@ -24,7 +66,8 @@ enum
   PROP_SOURCE_FOO,
   PROP_SOURCE_BAR,
   PROP_SOURCE_DOUBLE_VALUE,
-  PROP_SOURCE_TOGGLE
+  PROP_SOURCE_TOGGLE,
+  PROP_SOURCE_OBJECT
 };
 
 static GType binding_source_get_type (void);
@@ -56,6 +99,10 @@ binding_source_set_property (GObject      *gobject,
       source->toggle = g_value_get_boolean (value);
       break;
 
+    case PROP_SOURCE_OBJECT:
+      source->item = g_value_get_object (value);
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
     }
@@ -87,6 +134,10 @@ binding_source_get_property (GObject    *gobject,
       g_value_set_boolean (value, source->toggle);
       break;
 
+    case PROP_SOURCE_OBJECT:
+      g_value_set_object (value, source->item);
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
     }
@@ -119,6 +170,10 @@ binding_source_class_init (BindingSourceClass *klass)
                                    g_param_spec_boolean ("toggle", "Toggle", "Toggle",
                                                          FALSE,
                                                          G_PARAM_READWRITE));
+  g_object_class_install_property (gobject_class, PROP_SOURCE_OBJECT,
+                                   g_param_spec_object ("object", "Object", "Object",
+                                                        G_TYPE_OBJECT,
+                                                        G_PARAM_READWRITE));
 }
 
 static void
@@ -133,6 +188,7 @@ typedef struct _BindingTarget
   gint bar;
   gdouble double_value;
   gboolean toggle;
+  gpointer foo;
 } BindingTarget;
 
 typedef struct _BindingTargetClass
@@ -146,7 +202,8 @@ enum
 
   PROP_TARGET_BAR,
   PROP_TARGET_DOUBLE_VALUE,
-  PROP_TARGET_TOGGLE
+  PROP_TARGET_TOGGLE,
+  PROP_TARGET_FOO
 };
 
 static GType binding_target_get_type (void);
@@ -174,6 +231,10 @@ binding_target_set_property (GObject      *gobject,
       target->toggle = g_value_get_boolean (value);
       break;
 
+    case PROP_TARGET_FOO:
+      target->foo = g_value_get_object (value);
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
     }
@@ -201,6 +262,10 @@ binding_target_get_property (GObject    *gobject,
       g_value_set_boolean (value, target->toggle);
       break;
 
+    case PROP_TARGET_FOO:
+      g_value_set_object (value, target->foo);
+      break;
+
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
     }
@@ -228,6 +293,10 @@ binding_target_class_init (BindingTargetClass *klass)
                                    g_param_spec_boolean ("toggle", "Toggle", "Toggle",
                                                          FALSE,
                                                          G_PARAM_READWRITE));
+  g_object_class_install_property (gobject_class, PROP_TARGET_FOO,
+                                   g_param_spec_object ("foo", "Foo", "Foo",
+                                                        foo_get_type (),
+                                                        G_PARAM_READWRITE));
 }
 
 static void
@@ -757,6 +826,66 @@ binding_fail (void)
   g_assert_null (binding);
 }
 
+static gboolean
+transform_to_func (GBinding     *binding,
+                   const GValue *value_a,
+                   GValue       *value_b,
+                   gpointer      user_data)
+{
+  if (g_value_type_compatible (G_VALUE_TYPE (value_a), G_VALUE_TYPE (value_b)))
+    {
+      g_value_copy (value_a, value_b);
+      return TRUE;
+    }
+
+  if (g_value_type_transformable (G_VALUE_TYPE (value_a), G_VALUE_TYPE (value_b)))
+    {
+      if (g_value_transform (value_a, value_b))
+        return TRUE;
+    }
+
+  return FALSE;
+}
+
+static void
+binding_interface (void)
+{
+  BindingSource *source = g_object_new (binding_source_get_type (), NULL);
+  BindingTarget *target = g_object_new (binding_target_get_type (), NULL);
+  GObject *baa;
+  GBinding *binding;
+  GClosure *transform_to;
+
+  /* binding a generic object property to an interface-valued one */
+  binding = g_object_bind_property (source, "object",
+                                    target, "foo",
+                                    G_BINDING_DEFAULT);
+
+  baa = g_object_new (baa_get_type (), NULL);
+  g_object_set (source, "object", baa, NULL);
+  g_object_unref (baa);
+
+  g_binding_unbind (binding);
+
+  /* the same, with a generic marshaller */
+  transform_to = g_cclosure_new (G_CALLBACK (transform_to_func), NULL, NULL);
+  g_closure_set_marshal (transform_to, g_cclosure_marshal_generic);
+  binding = g_object_bind_property_with_closures (source, "object",
+                                                  target, "foo",
+                                                  G_BINDING_DEFAULT,
+                                                  transform_to,
+                                                  NULL);
+
+  baa = g_object_new (baa_get_type (), NULL);
+  g_object_set (source, "object", baa, NULL);
+  g_object_unref (baa);
+
+  g_binding_unbind (binding);
+
+  g_object_unref (source);
+  g_object_unref (target);
+}
+
 int
 main (int argc, char *argv[])
 {
@@ -778,6 +907,7 @@ main (int argc, char *argv[])
   g_test_add_func ("/binding/unbind-weak", binding_unbind_weak);
   g_test_add_func ("/binding/unbind-multiple", binding_unbind_multiple);
   g_test_add_func ("/binding/fail", binding_fail);
+  g_test_add_func ("/binding/interface", binding_interface);
 
   return g_test_run ();
 }