Add initial pytest support

Add a new dbusmock.pytest_fixtures module which exports an initial set
of fixtures. These mostly just wrap DbusTestCase into a fixture, plus
some convenience functions for starting a system or session bus. In the
future we may have more fixtures to spawn templates, etc.

Ensure that all of our unit tests run with pytest. As that is expensive,
only run it for TEST_CODE=1 in Fedora stable. On the others, only run
the basic TestAPI checks and the fixtures checks.

Thanks to @whot for the initial investigation and proposal!

dbusmock/pytest_fixtures.py

@@ -0,0 +1,41 @@
+'''pytest fixtures for DBusMock'''
+
+# This program is free software; you can redistribute it and/or modify it under
+# the terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation; either version 3 of the License, or (at your option) any
+# later version.  See http://www.gnu.org/copyleft/lgpl.html for the full text
+# of the license.
+
+__author__ = 'Martin Pitt'
+__copyright__ = '(c) 2023 Martin Pitt <[email protected]>'
+
+from typing import Iterator
+
+import pytest
+
+import dbusmock.testcase
+
+
+@pytest.fixture(scope='session')
+def dbusmock_testcase() -> Iterator[dbusmock.testcase.DBusTestCase]:
+    '''Export the whole DBusTestCase as a fixture.'''
+
+    testcase = dbusmock.testcase.DBusTestCase()
+    yield testcase
+    testcase.tearDownClass()
+
+
+@pytest.fixture(scope='session')
+def dbusmock_testcase_system(dbusmock_testcase) -> Iterator[dbusmock.testcase.DBusTestCase]:
+    '''Export the whole DBusTestCase as a fixture, with system bus started'''
+
+    dbusmock_testcase.start_system_bus()
+    yield dbusmock_testcase
+
+
+@pytest.fixture(scope='session')
+def dbusmock_testcase_session(dbusmock_testcase) -> Iterator[dbusmock.testcase.DBusTestCase]:
+    '''Export the whole DBusTestCase as a fixture, with session bus started'''
+
+    dbusmock_testcase.start_session_bus()
+    yield dbusmock_testcase

tests/conftest.py

@@ -0,0 +1 @@
+pytest_plugins = "dbusmock.pytest_fixtures"

tests/run-debian

@@ -13,7 +13,7 @@ eatmydata apt-get -y --purge dist-upgrade
 # install build dependencies
 eatmydata apt-get install --no-install-recommends -y git \
     python3-all python3-setuptools python3-setuptools-scm python3-build python3-venv \
-    python3-dbus python3-gi gir1.2-glib-2.0 \
+    python3-dbus python3-pytest python3-gi gir1.2-glib-2.0 \
     dbus libnotify-bin upower network-manager bluez ofono ofono-scripts
 
 # systemd's tools otherwise fail on "not been booted with systemd"
@@ -27,6 +27,7 @@ export TEST_CODE="$TEST_CODE"
 cp -r $(pwd) /tmp/source
 cd /tmp/source
 python3 -m unittest -v
+pytest -vv -k 'test_pytest or TestAPI'
 # massively parallel test to check for races
 for i in \$(seq 100); do
     ( PYTHONPATH=. python3 tests/test_api.py TestTemplates || touch /tmp/fail ) &

tests/run-fedora

@@ -2,7 +2,7 @@
 set -eux
 # install build dependencies
 dnf -y install python3-setuptools python3 python3-gobject-base \
-    python3-dbus dbus-x11 util-linux \
+    python3-dbus python3-pytest dbus-x11 util-linux \
     upower NetworkManager bluez libnotify polkit
 
 if ! grep -q :el /etc/os-release; then
@@ -31,4 +31,12 @@ python3 -m unittest -v || {
   [ -z "$DEBUG" ] || sleep infinity
   exit 1
 }
+
+# run all tests with pytest only on TEST_CODE, as that is expensive
+if [ -n "$TEST_CODE"]; then
+    pytest -v
+else
+    pytest -vv -k 'test_pytest or TestAPI'
+fi
+fi
 EOF

tests/test_pytest.py

@@ -0,0 +1,29 @@
+import subprocess
+
+import dbusmock
+
+
+def test_dbusmock_testcase_spawn_server(dbusmock_testcase_session):
+    test_iface = 'org.freedesktop.Test.Main'
+
+    p_mock = dbusmock_testcase_session.spawn_server(
+        'org.freedesktop.Test', '/', test_iface, stdout=subprocess.DEVNULL)
+
+    obj_test = dbusmock_testcase_session.get_dbus().get_object('org.freedesktop.Test', '/')
+
+    obj_test.AddMethod('', 'Upper', 's', 's', 'ret = args[0].upper()', interface_name=dbusmock.MOCK_IFACE)
+    assert obj_test.Upper('hello', interface=test_iface) == 'HELLO'
+
+    p_mock.terminate()
+    p_mock.wait()
+
+
+def test_dbusmock_testcase_spawn_system_template(dbusmock_testcase_system):
+    p_mock, _obj = dbusmock_testcase_system.spawn_server_template('upower', stdout=subprocess.DEVNULL)
+
+    out = subprocess.check_output(['upower', '--dump'], universal_newlines=True)
+    assert 'version:' in out
+    assert '0.99' in out
+
+    p_mock.terminate()
+    p_mock.wait()