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.

This was co-developed with Peter Hutterer @whot, thank you!

README.md

@@ -36,15 +36,15 @@ When using a local system/session bus, you can do unit or integration
 testing without needing root privileges or disturbing a running system.
 The Python API offers some convenience functions like
 `start_session_bus()` and `start_system_bus()` for this, in a
-`DBusTestCase` class (subclass of the standard `unittest.TestCase`).
+`DBusTestCase` class (subclass of the standard `unittest.TestCase`) or
+alternatively as a `@pytest.fixture`.
 
 You can use this with any programming language, as you can run the
 mocker as a normal program. The actual setup of the mock (adding
 objects, methods, properties, and signals) all happen via D-Bus methods
 on the `org.freedesktop.DBus.Mock` interface. You just don't have the
 convenience D-Bus launch API that way.
-
-## Simple example in Python
+## Simple example using Python's unittest
 
 Picking up the above example about mocking upower's `Suspend()` method,
 this is how you would set up a mock upower in your test case:
@@ -125,6 +125,80 @@ Let's walk through:
      together with a time stamp; you can use the latter for doing
      timing related tests, but we just ignore it here.
 
+## Simple example using pytest
+
+The same functionality as above but instead using the pytest fixture provided
+by this package.
+
+```python
+import subprocess
+
+import dbus
+import pytest
+
+import dbusmock
+
+
+@pytest.fixture
+def upower_mock(dbusmock_testcase_system):
+    p_mock = dbusmock_testcase_system.spawn_server(
+        'org.freedesktop.UPower',
+        '/org/freedesktop/UPower',
+        'org.freedesktop.UPower',
+        system_bus=True,
+        stdout=subprocess.PIPE)
+
+    # Get a proxy for the UPower object's Mock interface
+    dbus_upower_mock = dbus.Interface(dbusmock_testcase_system.get_dbus(True).get_object(
+        'org.freedesktop.UPower',
+        '/org/freedesktop/UPower'
+    ), dbusmock.MOCK_IFACE)
+    dbus_upower_mock.AddMethod('', 'Suspend', '', '', '')
+
+    yield p_mock
+
+    p_mock.stdout.close()
+    p_mock.terminate()
+    p_mock.wait()
+
+
+def test_suspend_on_idle(upower_mock):
+    # run your program in a way that should trigger one suspend call
+
+    # now check the log that we got one Suspend() call
+    assert upower_mock.stdout.readline() == b'^[0-9.]+ Suspend$'
+```
+
+Let's walk through:
+
+- We import the `system_mock` fixture from dbusmock which provides us
+  with a system bus started for our test case wherever the
+  `dbusmock_testcase_system` argument is used by a test case and/or a pytest
+  fixture.
+
+- The `upower_mock` fixture spawns the mock D-Bus server process for an initial
+  `/org/freedesktop/UPower` object with an `org.freedesktop.UPower`
+  D-Bus interface on the system bus. We capture its stdout to be
+  able to verify that methods were called.
+
+  We then call `org.freedesktop.DBus.Mock.AddMethod()` to add a
+  `Suspend()` method to our new object to the default D-Bus
+  interface. This will not do anything (except log its call to
+  stdout). It takes no input arguments, returns nothing, and does
+  not run any custom code.
+
+  This mock server process is yielded to the test function that uses
+  the `upower_mock` fixture - once the test is complete the process is
+  terminated again.
+
+- `test_suspend_on_idle()` is the actual test case. It needs to run
+  your program in a way that should trigger one suspend call. Your
+  program will try to call `Suspend()`, but as that's now being
+  served by our mock instead of upower, there will not be any actual
+  machine suspend. Our mock process will log the method call
+  together with a time stamp; you can use the latter for doing
+  timing related tests, but we just ignore it here.
+
 ## Simple example from shell
 
 We use the actual session bus for this example. You can use
@@ -301,9 +375,7 @@ the mock server as a program.
 
 python-dbusmock is hosted on https://github.com/martinpitt/python-dbusmock
 
-Run the unit tests with
-
-    python3 -m unittest
+Run the unit tests with `python3 -m unittest` or `pytest`.
 
 In CI, the unit tests run in containers. You can run them locally with e.g.
 

dbusmock/pytest_fixtures.py

@@ -0,0 +1,43 @@
+'''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 <martin@piware.de>'
+
+from typing import Iterator
+
+import pytest
+
+import dbusmock.testcase
+
+
+@pytest.fixture(name='dbusmock_testcase', scope='session')
+def fixture_dbusmock_testcase() -> Iterator[dbusmock.testcase.DBusTestCase]:
+    '''Export the whole DBusTestCase as a fixture.'''
+
+    testcase = dbusmock.testcase.DBusTestCase()
+    testcase.setUp()
+    yield testcase
+    testcase.tearDown()
+    testcase.tearDownClass()
+
+
+@pytest.fixture(scope='session')
+def dbusmock_testcase_system(dbusmock_testcase) -> dbusmock.testcase.DBusTestCase:
+    '''Export the whole DBusTestCase as a fixture, with system bus started'''
+
+    dbusmock_testcase.start_system_bus()
+    return dbusmock_testcase
+
+
+@pytest.fixture(scope='session')
+def dbusmock_testcase_session(dbusmock_testcase) -> dbusmock.testcase.DBusTestCase:
+    '''Export the whole DBusTestCase as a fixture, with session bus started'''
+
+    dbusmock_testcase.start_session_bus()
+    return dbusmock_testcase

packaging/python-dbusmock.spec

@@ -15,6 +15,7 @@ BuildRequires:    python3-dbus
 BuildRequires:    python3-devel
 BuildRequires:    python3-setuptools
 BuildRequires:    python3-gobject
+BuildRequires:    python3-pytest
 BuildRequires:    dbus-x11
 BuildRequires:    upower
 

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
+python3 -m 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
@@ -19,12 +19,17 @@ mkdir -p /run/systemd/system
 
 # run build and test as user
 useradd build
-su -s /bin/sh - build << EOF
+su -s /bin/sh - build << EOF || { [ -z "$DEBUG" ] || sleep infinity; exit 1; }
 set -ex
 cd /source
 export TEST_CODE="$TEST_CODE"
-python3 -m unittest -v || {
-  [ -z "$DEBUG" ] || sleep infinity
-  exit 1
-}
+
+python3 -m unittest -v
+
+# run all tests with pytest only on TEST_CODE, as that is expensive
+if [ -n "$TEST_CODE" ]; then
+    python3 -m pytest -v
+else
+    python3 -m pytest -vv -k 'test_pytest or TestAPI'
+fi
 EOF

tests/test_api_pytest.py

@@ -0,0 +1,36 @@
+import subprocess
+import tempfile
+
+import pytest
+
+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=tempfile.TemporaryFile())
+
+    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()
+
+
+@pytest.fixture(name='upower_mock')
+def fixture_upower_mock(dbusmock_testcase_system):
+    p_mock, obj = dbusmock_testcase_system.spawn_server_template('upower', stdout=subprocess.DEVNULL)
+    yield obj
+    p_mock.terminate()
+    p_mock.wait()
+
+
+def test_dbusmock_testcase_spawn_system_template(upower_mock):
+    assert upower_mock
+    out = subprocess.check_output(['upower', '--dump'], universal_newlines=True)
+    assert 'version:' in out
+    assert '0.99' in out