test: add a mock webserver in Python

This is roughly a replacement for test-server.  It's an outline for what
a simple cockpit-ws in Python might look like (albeit without any of the
necessary authentication code).  It's already useful enough to run the
majority of the existing QUnit, which means we can now run most unit
tests without needing to build any C code.

pyproject.toml

@@ -166,6 +166,10 @@ ignore_decorators = [
    "@pytest.fixture",
    "@pytest.hookimpl",
 ]
+exclude = [
+    "test/pytest/mockdbusservice.py",
+    "test/pytest/mockwebserver.py",
+]
 
 [tool.coverage.paths]
 source = ["src", "*/site-packages"]

test/conftest.py

@@ -0,0 +1,43 @@
+import os
+import subprocess
+from typing import Iterator
+
+import pytest
+
+from cockpit._vendor import systemd_ctypes
+
+
+# run tests on a private user bus
+@pytest.fixture(scope='session', autouse=True)
+def mock_session_bus(tmp_path_factory: pytest.TempPathFactory) -> Iterator[None]:
+    # make sure nobody opened the user bus yet...
+    assert systemd_ctypes.Bus._default_user_instance is None
+
+    tmpdir = tmp_path_factory.getbasetemp()
+    dbus_config = tmpdir / 'dbus-config'
+    dbus_addr = f'unix:path={tmpdir / "dbus_socket"}'
+
+    dbus_config.write_text(fr"""
+      <busconfig>
+        <fork/>
+        <type>session</type>
+        <listen>{dbus_addr}</listen>
+        <policy context="default">
+          <!-- Allow everything to be sent -->
+          <allow send_destination="*" eavesdrop="true"/>
+          <!-- Allow everything to be received -->
+          <allow eavesdrop="true"/>
+          <!-- Allow anyone to own anything -->
+          <allow own="*"/>
+        </policy>
+      </busconfig>
+    """)
+    dbus_daemon = subprocess.run(
+        ['dbus-daemon', f'--config-file={dbus_config}', '--print-pid'], stdout=subprocess.PIPE
+    )
+    pid = int(dbus_daemon.stdout)
+    try:
+        os.environ['DBUS_SESSION_BUS_ADDRESS'] = dbus_addr
+        yield None
+    finally:
+        os.kill(pid, 9)

test/pytest/mockdbusservice.py

@@ -0,0 +1,171 @@
+import asyncio
+import contextlib
+import logging
+import math
+from collections.abc import AsyncIterator
+from typing import Iterator
+
+from cockpit._vendor import systemd_ctypes
+
+logger = logging.getLogger(__name__)
+
+
+# No introspection, manual handling of method calls
+class borkety_Bork(systemd_ctypes.bus.BaseObject):
+    def message_received(self, message: systemd_ctypes.bus.BusMessage) -> bool:
+        signature = message.get_signature(True)  # noqa:FBT003
+        body = message.get_body()
+        logger.debug('got Bork message: %s %r', signature, body)
+
+        if message.get_member() == 'Echo':
+            message.reply_method_return(signature, *body)
+            return True
+
+        return False
+
+
+class com_redhat_Cockpit_DBusTests_Frobber(systemd_ctypes.bus.Object):
+    finally_normal_name = systemd_ctypes.bus.Interface.Property('s', 'There aint no place like home')
+    readonly_property = systemd_ctypes.bus.Interface.Property('s', 'blah')
+    aay = systemd_ctypes.bus.Interface.Property('aay', [], name='aay')
+    ag = systemd_ctypes.bus.Interface.Property('ag', [], name='ag')
+    ao = systemd_ctypes.bus.Interface.Property('ao', [], name='ao')
+    as_ = systemd_ctypes.bus.Interface.Property('as', [], name='as')
+    ay = systemd_ctypes.bus.Interface.Property('ay', b'ABCabc\0', name='ay')
+    b = systemd_ctypes.bus.Interface.Property('b', value=False, name='b')
+    d = systemd_ctypes.bus.Interface.Property('d', 43, name='d')
+    g = systemd_ctypes.bus.Interface.Property('g', '', name='g')
+    i = systemd_ctypes.bus.Interface.Property('i', 0, name='i')
+    n = systemd_ctypes.bus.Interface.Property('n', 0, name='n')
+    o = systemd_ctypes.bus.Interface.Property('o', '/', name='o')
+    q = systemd_ctypes.bus.Interface.Property('q', 0, name='q')
+    s = systemd_ctypes.bus.Interface.Property('s', '', name='s')
+    t = systemd_ctypes.bus.Interface.Property('t', 0, name='t')
+    u = systemd_ctypes.bus.Interface.Property('u', 0, name='u')
+    x = systemd_ctypes.bus.Interface.Property('x', 0, name='x')
+    y = systemd_ctypes.bus.Interface.Property('y', 42, name='y')
+
+    test_signal = systemd_ctypes.bus.Interface.Signal('i', 'as', 'ao', 'a{s(ii)}')
+
+    @systemd_ctypes.bus.Interface.Method('', 'i')
+    def request_signal_emission(self, which_one: int) -> None:
+        del which_one
+
+        self.test_signal(
+            43,
+            ['foo', 'frobber'],
+            ['/foo', '/foo/bar'],
+            {'first': (42, 42), 'second': (43, 43)}
+        )
+
+    @systemd_ctypes.bus.Interface.Method('s', 's')
+    def hello_world(self, greeting: str) -> str:
+        return f"Word! You said `{greeting}'. I'm Skeleton, btw!"
+
+    @systemd_ctypes.bus.Interface.Method('', '')
+    async def never_return(self) -> None:
+        await asyncio.sleep(1000000)
+
+    @systemd_ctypes.bus.Interface.Method(
+        ['y', 'b', 'n', 'q', 'i', 'u', 'x', 't', 'd', 's', 'o', 'g', 'ay'],
+        ['y', 'b', 'n', 'q', 'i', 'u', 'x', 't', 'd', 's', 'o', 'g', 'ay']
+    )
+    def test_primitive_types(
+        self,
+        val_byte, val_boolean,
+        val_int16, val_uint16, val_int32, val_uint32, val_int64, val_uint64,
+        val_double,
+        val_string, val_objpath, val_signature,
+        val_bytestring
+    ):
+        return [
+            val_byte + 10,
+            not val_boolean,
+            100 + val_int16,
+            1000 + val_uint16,
+            10000 + val_int32,
+            100000 + val_uint32,
+            1000000 + val_int64,
+            10000000 + val_uint64,
+            val_double / math.pi,
+            f"Word! You said `{val_string}'. Rock'n'roll!",
+            f"/modified{val_objpath}",
+            f"assgit{val_signature}",
+            b"bytestring!\xff\0"
+        ]
+
+    @systemd_ctypes.bus.Interface.Method(
+        ['s'],
+        ["a{ss}", "a{s(ii)}", "(iss)", "as", "ao", "ag", "aay"]
+    )
+    def test_non_primitive_types(
+        self,
+        dict_s_to_s,
+        dict_s_to_pairs,
+        a_struct,
+        array_of_strings,
+        array_of_objpaths,
+        array_of_signatures,
+        array_of_bytestrings
+    ):
+        return (
+            f'{dict_s_to_s}{dict_s_to_pairs}{a_struct}'
+            f'array_of_strings: [{", ".join(array_of_strings)}] '
+            f'array_of_objpaths: [{", ".join(array_of_objpaths)}] '
+            f'array_of_signatures: [signature {", ".join(f"'{sig}'" for sig in array_of_signatures)}] '
+            f'array_of_bytestrings: [{", ".join(x[:-1].decode() for x in array_of_bytestrings)}] '
+        )
+
+
+@contextlib.contextmanager
+def mock_service_export(bus: systemd_ctypes.Bus) -> Iterator[None]:
+    slots = [
+        bus.add_object('/otree/frobber', com_redhat_Cockpit_DBusTests_Frobber()),
+        bus.add_object('/otree/different', com_redhat_Cockpit_DBusTests_Frobber()),
+        bus.add_object('/bork', borkety_Bork())
+    ]
+
+    yield
+
+    for slot in slots:
+        slot.cancel()
+
+
+@contextlib.asynccontextmanager
+async def well_known_name(bus: systemd_ctypes.Bus, name: str, flags: int = 0) -> AsyncIterator[None]:
+    result, = await bus.call_method_async(
+        'org.freedesktop.DBus', '/org/freedesktop/DBus', 'org.freedesktop.DBus', 'RequestName', 'su', name, flags
+    )
+    if result != 1:
+        raise RuntimeError(f'Cannot register name {name}: {result}')
+
+    try:
+        yield
+
+    finally:
+        result, = await bus.call_method_async(
+            'org.freedesktop.DBus', '/org/freedesktop/DBus', 'org.freedesktop.DBus', 'ReleaseName', 's', name
+        )
+        if result != 1:
+            raise RuntimeError(f'Cannot release name {name}: {result}')
+
+
+@contextlib.asynccontextmanager
+async def mock_dbus_service_on_user_bus() -> AsyncIterator[None]:
+    user = systemd_ctypes.Bus.default_user()
+    async with (
+        well_known_name(user, 'com.redhat.Cockpit.DBusTests.Test'),
+        well_known_name(user, 'com.redhat.Cockpit.DBusTests.Second'),
+    ):
+        with mock_service_export(user):
+            yield
+
+
+async def main():
+    async with mock_dbus_service_on_user_bus():
+        print('Mock service running.  Ctrl+C to exit.')
+        await asyncio.sleep(2 << 30)  # "a long time."
+
+
+if __name__ == '__main__':
+    systemd_ctypes.run_async(main())