tests: add test for buffer release event

Tests especially, that attach-attach-commit does not result in a release
of the first buffer.

Also tests, that the old buffer is released when a new buffer has been
attached, committed, and displayed (frame callback).

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>

tests/event-test.c

@@ -1,5 +1,6 @@
 /*
  * Copyright © 2012 Intel Corporation
+ * Copyright © 2013 Collabora, Ltd.
  *
  * Permission to use, copy, modify, distribute, and sell this software and
  * its documentation for any purpose is hereby granted without fee, provided
@@ -347,3 +348,71 @@ TEST(test_surface_output)
 	check_client_move(client, x, --y);
 	assert(output_contains_client(client));
 }
+
+static void
+buffer_release_handler(void *data, struct wl_buffer *buffer)
+{
+	int *released = data;
+
+	*released = 1;
+}
+
+static struct wl_buffer_listener buffer_listener = {
+	buffer_release_handler
+};
+
+TEST(buffer_release)
+{
+	struct client *client;
+	struct wl_surface *surface;
+	struct wl_buffer *buf1;
+	struct wl_buffer *buf2;
+	struct wl_buffer *buf3;
+	int buf1_released = 0;
+	int buf2_released = 0;
+	int buf3_released = 0;
+	int frame;
+
+	client = client_create(100, 100, 100, 100);
+	assert(client);
+	surface = client->surface->wl_surface;
+
+	buf1 = create_shm_buffer(client, 100, 100, NULL);
+	wl_buffer_add_listener(buf1, &buffer_listener, &buf1_released);
+
+	buf2 = create_shm_buffer(client, 100, 100, NULL);
+	wl_buffer_add_listener(buf2, &buffer_listener, &buf2_released);
+
+	buf3 = create_shm_buffer(client, 100, 100, NULL);
+	wl_buffer_add_listener(buf3, &buffer_listener, &buf3_released);
+
+	/*
+	 * buf1 must never be released, since it is replaced before
+	 * it is committed, therefore it never becomes busy.
+	 */
+
+	wl_surface_attach(surface, buf1, 0, 0);
+	wl_surface_attach(surface, buf2, 0, 0);
+	frame_callback_set(surface, &frame);
+	wl_surface_commit(surface);
+	frame_callback_wait(client, &frame);
+	assert(buf1_released == 0);
+	/* buf2 may or may not be released */
+	assert(buf3_released == 0);
+
+	wl_surface_attach(surface, buf3, 0, 0);
+	frame_callback_set(surface, &frame);
+	wl_surface_commit(surface);
+	frame_callback_wait(client, &frame);
+	assert(buf1_released == 0);
+	assert(buf2_released == 1);
+	/* buf3 may or may not be released */
+
+	wl_surface_attach(surface, client->surface->wl_buffer, 0, 0);
+	frame_callback_set(surface, &frame);
+	wl_surface_commit(surface);
+	frame_callback_wait(client, &frame);
+	assert(buf1_released == 0);
+	assert(buf2_released == 1);
+	assert(buf3_released == 1);
+}