tests: wait for session in tests requiring running GUI

Since tests expose qubesd socket, qvm-start-gui should handle starting
GUI daemons (so, GUI session inside VM). Add synchronization with it
using qubes.WaitForSession service.

qubes/tests/__init__.py

@@ -938,6 +938,13 @@ def create_remote_file(self, vm, filename, content):
             'cat > {}'.format(shlex.quote(filename)),
             user='root', input=content.encode('utf-8')))
 
+    @asyncio.coroutine
+    def wait_for_session(self, vm):
+        yield from asyncio.wait_for(
+            vm.run_service_for_stdio(
+                'qubes.WaitForSession', input=vm.default_user.encode()),
+            timeout=30)
+
 
 def load_tests(loader, tests, pattern): # pylint: disable=unused-argument
     # discard any tests from this module, because it hosts base classes

qubes/tests/integ/vm_qrexec_gui.py

@@ -68,6 +68,7 @@ def test_010_run_xterm(self):
         self.loop.run_until_complete(self.testvm1.start())
         self.assertEqual(self.testvm1.get_power_state(), "Running")
 
+        self.loop.run_until_complete(self.wait_for_session(self.testvm1))
         p = self.loop.run_until_complete(self.testvm1.run('xterm'))
         try:
             wait_count = 0
@@ -110,6 +111,7 @@ def test_011_run_gnome_terminal(self):
             self.skipTest("Minimal template doesn't have 'gnome-terminal'")
         self.loop.run_until_complete(self.testvm1.start())
         self.assertEqual(self.testvm1.get_power_state(), "Running")
+        self.loop.run_until_complete(self.wait_for_session(self.testvm1))
         p = self.loop.run_until_complete(self.testvm1.run('gnome-terminal'))
         try:
             title = 'user@{}'.format(self.testvm1.name)
@@ -163,6 +165,7 @@ def test_012_qubes_desktop_run(self):
             pass
         else:
             xterm_desktop_path = xterm_desktop_path_debian
+        self.loop.run_until_complete(self.wait_for_session(self.testvm1))
         self.loop.run_until_complete(
             self.testvm1.run('qubes-desktop-run {}'.format(xterm_desktop_path)))
         title = 'user@{}'.format(self.testvm1.name)
@@ -687,6 +690,8 @@ def test_130_qrexec_filemove_disk_full(self):
             self.testvm1.start(),
             self.testvm2.start()]))
 
+        self.loop.run_until_complete(self.wait_for_session(self.testvm1))
+
         # Prepare test file
         self.loop.run_until_complete(self.testvm1.run_for_stdio(
             'yes teststring | dd of=testfile bs=1M count=50 iflag=fullblock'))
@@ -818,6 +823,7 @@ def _test_300_bug_1028_gui_memory_pinning(self):
         # exclude from memory balancing
         self.testvm1.features['services/meminfo-writer'] = False
         yield from self.testvm1.start()
+        yield from self.wait_for_session(self.testvm1)
 
         # and allow large map count
         yield from self.testvm1.run('echo 256000 > /proc/sys/vm/max_map_count',