tests: use mocks to allow calling virEventRegisterImpl many times

We currently have to run each of the test_aio.py test cases in a
separate process, because libvirt.virEventRegisterImpl can only be
called once per process. This leads to quite unpleasant console
output when running tests.

By introducing a mock for libvirt.virEventRegisterImpl we can
regain the ability to run everything in a single process. The only
caveat is that it relies on tests to fully cleanup, but in practice
this is ok for our current tests.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

setup.py

@@ -310,19 +310,7 @@ class my_test(Command):
             os.environ["PYTHONPATH"] = self.build_platlib
 
         pytest = self.find_pytest_path()
-
-        # Run the normal tests.
-        subprocess.check_call([pytest, "-m", "not separate_process"])
-
-        # Run the tests that require their own process.
-        testlist = subprocess.run(
-            [pytest, "--collect-only", "--quiet", "-m", "separate_process"],
-            check=True, stdout=subprocess.PIPE)
-        testlist = testlist.stdout.decode("utf-8").splitlines()
-        testlist = filter(
-            lambda test: test and "tests collected" not in test, testlist)
-        for test in testlist:
-            subprocess.check_call([pytest, test])
+        subprocess.check_call([pytest])
 
 class my_clean(Command):
     def run(self):