In refcount test don't rely on PsyGlCanvas

In the unit tests in the/a CI framework, it might be hard
to get an opengl canvas, and for this test another object might just
suffice.

tests/test-ref-count.c

@@ -5,111 +5,86 @@
 #include <CUnit/CUnit.h>
 #include <psylib.h>
 
-static PsyCanvas *canvas = NULL;
-
-static int
-init_window(void)
-{
-    canvas = PSY_CANVAS(psy_image_canvas_new(640, 480));
-    if (canvas)
-        return 0;
-    else
-        return 1;
-}
-
-static int
-destoy_window(void)
-{
-    assert(G_OBJECT(canvas)->ref_count == 1);
-    g_object_unref(canvas);
-    canvas = NULL;
-    return 0;
-}
-
 static void
 ref_starts_with_one(void)
 {
-    PsyCircle *circle = g_object_new(PSY_TYPE_CIRCLE, "canvas", canvas, NULL);
-    PsyColor  *color  = g_object_new(PSY_TYPE_COLOR, NULL);
-    GObject   *circle_gobj = G_OBJECT(circle);
-    GObject   *color_gobj  = G_OBJECT(color);
+    PsyColor *color      = g_object_new(PSY_TYPE_COLOR, NULL);
+    GObject  *color_gobj = G_OBJECT(color);
 
-    CU_ASSERT_EQUAL(circle_gobj->ref_count, 1);
     CU_ASSERT_EQUAL(color_gobj->ref_count, 1);
 
-    g_object_unref(circle);
     g_object_unref(color);
 }
 
 static void
-ref_set_method(void)
+transfer_none_method(void)
 {
-    PsyCircle *circle = g_object_new(PSY_TYPE_CIRCLE, "canvas", canvas, NULL);
-    PsyColor  *color  = g_object_new(PSY_TYPE_COLOR, NULL);
+    // clang-format off
+    PsyImage *image = g_object_new(PSY_TYPE_IMAGE,
+                                   "width", 640,
+                                   "height", 480,
+                                   "format", PSY_IMAGE_FORMAT_RGB,
+                                   NULL);
+    // clang-format on
+
+    CU_ASSERT_PTR_NOT_NULL_FATAL(image);
+    PsyColor *color = g_object_new(PSY_TYPE_COLOR, NULL);
 
     // Cast to conveniently obtain the reference count
-    GObject *circle_gobj = G_OBJECT(circle);
-    GObject *color_gobj  = G_OBJECT(color);
+    GObject *image_gobj = G_OBJECT(image);
+    GObject *color_gobj = G_OBJECT(color);
 
     /*
      * This is (transfer none), so we should free it.
      */
-    psy_visual_stimulus_set_color(PSY_VISUAL_STIMULUS(circle), color);
+    psy_visual_stimulus_set_color(PSY_VISUAL_STIMULUS(image), color);
 
-    CU_ASSERT_EQUAL(circle_gobj->ref_count, 1);
+    CU_ASSERT_EQUAL(image_gobj->ref_count, 1);
     CU_ASSERT_EQUAL(color_gobj->ref_count, 1);
 
-    // The circle disposes its reference to color
-    g_object_unref(circle);
-
+    g_object_unref(image);
     CU_ASSERT_EQUAL(color_gobj->ref_count, 1);
-
     g_object_unref(color);
 }
 
 static void
-ref_set_property(void)
+set_property_transfer_full(void)
 {
-    PsyCircle *circle = g_object_new(PSY_TYPE_CIRCLE, "canvas", canvas, NULL);
-    PsyColor  *color  = g_object_new(PSY_TYPE_COLOR, NULL);
-    GObject   *circle_gobj = G_OBJECT(circle);
-    GObject   *color_gobj  = G_OBJECT(color);
+    PsyTrial *trial = psy_trial_new();
+    PsyLoop  *loop  = psy_loop_new();
 
-    CU_ASSERT_EQUAL(circle_gobj->ref_count, 1);
-    CU_ASSERT_EQUAL(color_gobj->ref_count, 1);
+    // Cast to gobject to easily access refcount.
+    GObject *trial_gobj = G_OBJECT(trial);
+    GObject *loop_gobj  = G_OBJECT(loop);
 
-    // Circle is owning a duplicate
-    g_object_set(circle, "color", color, NULL);
+    CU_ASSERT_EQUAL(trial_gobj->ref_count, 1);
+    CU_ASSERT_EQUAL(loop_gobj->ref_count, 1);
 
-    CU_ASSERT_EQUAL(circle_gobj->ref_count, 1);
-    CU_ASSERT_EQUAL(color_gobj->ref_count, 1);
+    g_object_set(loop, "child", trial, NULL); // transfer full
 
-    g_object_unref(circle); // Circle disposes its reference on color
-    CU_ASSERT_EQUAL(color_gobj->ref_count, 1);
+    CU_ASSERT_EQUAL(trial_gobj->ref_count, 1); // hence still one.
 
-    g_object_unref(color);
+    g_object_unref(loop);
 }
 
 int
 add_ref_count_suite(void)
 {
-    CU_Suite *suite
-        = CU_add_suite("test reference count", init_window, destoy_window);
-    CU_Test *test = NULL;
+    CU_Suite *suite = CU_add_suite("test reference count", NULL, NULL);
+    CU_Test  *test  = NULL;
 
     if (!suite)
         return 1;
 
-    test = CU_add_test(
-        suite, "Object start with reference of 1", ref_starts_with_one);
+    test = CU_ADD_TEST(suite, ref_starts_with_one);
     if (!test)
         return 1;
 
-    test = CU_add_test(suite, "Objects ref set method", ref_set_method);
+    test = CU_ADD_TEST(suite, transfer_none_method);
     if (!test)
         return 1;
 
-    test = CU_add_test(suite, "Objects ref set property", ref_set_property);
+    test = CU_ADD_TEST(suite, set_property_transfer_full);
     if (!test)
         return 1;