Fix race condition in gapplication/basic test

The three processes this test creates need to be executed
in order, and g_usleep was used to guarantee that.
However, under heavy load, that is not enough. Instead,
wait until the children start by making sure they have
written to stdout before proceeding any further.

https://bugzilla.gnome.org/show_bug.cgi?id=664627

diff --git a/gio/tests/gapplication.c b/gio/tests/gapplication.c
index 6e247a8..8769693 100644 (file)
--- a/gio/tests/gapplication.c
+++ b/gio/tests/gapplication.c
@@ -61,6 +61,7 @@ spawn (const gchar *expected_stdout,
   gchar **args;
   va_list ap;
   GPid pid;
+  GPollFD fd;
 
   va_start (ap, first_arg);
   array = g_ptr_array_new ();
@@ -83,6 +84,14 @@ spawn (const gchar *expected_stdout,
 
   g_child_watch_add (pid, child_quit, data);
   outstanding_watches++;
+
+  /* we block until the children write to stdout to make sure
+   * they have started, as they need to be executed in order;
+   * see https://bugzilla.gnome.org/show_bug.cgi?id=664627
+   */
+  fd.fd = data->stdout_pipe;
+  fd.events = G_IO_IN | G_IO_HUP | G_IO_ERR;
+  g_poll (&fd, 1, -1);
 }
 
 static void
@@ -102,16 +111,10 @@ basic (void)
          "exit status: 0\n",
          "./app", NULL);
 
-  /* make sure it becomes the master */
-  g_usleep (100000);
-
   /* send it some files */
   spawn ("exit status: 0\n",
          "./app", "/a", "/b", NULL);
 
-  /* make sure the commandline arrives after the files */
-  g_usleep (100000);
-
   spawn ("40 + 2 = 42\n"
          "exit status: 42\n",
          "./cmd", "40 +", "2", NULL);