Use headless mutter for monitor tests

Add some monitor tests that are using headless
mutter, and python with our in-tree gir files.

So far, we test that we get expected signals
when monitors are added and removed.

tests/headless-monitor-tests.py

@@ -0,0 +1,187 @@
+import sys
+import subprocess
+import gi
+
+gi.require_version('Gdk', '4.0')
+
+from gi.repository import GLib, Gdk
+from pydbus import SessionBus
+
+verbose = True
+
+screen_cast = None
+monitors = {}
+waiting = False
+done = False
+monitor_model = None
+
+def terminate():
+    for key in monitors:
+        monitor = monitors[key];
+        pipeline = monitor['pipeline'];
+        pipeline.terminate()
+    sys.exit(1)
+
+def stream_added_closure(name):
+    def stream_added(node_id):
+        monitor = monitors[name];
+
+        freq = monitor['freq'];
+        width = monitor['width'];
+        height = monitor['height'];
+        # FIXME scale = monitor['scale'];
+
+        # Use gstreamer out-of-process, since the gst gl support gets
+        # itself into a twist with its wayland connection when monitors
+        # disappear
+        pipeline_desc = f'gst-launch-1.0 pipewiresrc path={node_id} ! video/x-raw,max-framerate={freq}/1,width={width},height={height} ! videoconvert ! glimagesink'
+        if verbose:
+            print(f'launching {pipeline_desc}')
+        monitor['pipeline'] = subprocess.Popen([pipeline_desc], shell=True, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+
+    return stream_added
+
+def add_monitor(name, width, height, scale, freq):
+    if verbose:
+        print(f'add monitor {name}: {width}x{height}, scale {scale}, frequency {freq}')
+    session_path = screen_cast.CreateSession({})
+    session = bus.get('org.gnome.Mutter.ScreenCast', session_path)
+    monitors[name] = {
+        "session": session,
+        "width": width,
+        "height": height,
+        "scale": scale,
+        "freq": freq
+    }
+    stream_path = session.RecordVirtual({})
+    stream = bus.get('org.gnome.Mutter.ScreenCast', stream_path)
+    stream.onPipeWireStreamAdded = stream_added_closure(name)
+    session.Start()
+
+def remove_monitor(name):
+    if verbose:
+        print(f'remove monitor {name}')
+    try:
+        monitor = monitors[name];
+        pipeline = monitor['pipeline']
+        pipeline.kill()
+        session = monitor['session']
+        session.Stop()
+    except KeyError:
+        print("failed to remove monitor")
+    monitors[name] = None
+
+expected_change = None
+loop = None
+
+def quit_cb(loop):
+    loop.quit()
+
+def wait(millis):
+    global loop
+    loop = GLib.MainLoop()
+    GLib.timeout_add(millis, quit_cb, loop)
+    loop.run()
+
+def monitors_changed(monitors, position, removed, added):
+    global expected_change
+
+    assert expected_change != None, "No change expected"
+    assert position == expected_change['position'], "Unexpected position in monitors-changed"
+    assert removed == expected_change['removed'], "Unexpected removed in monitors-changed"
+    assert added == expected_change['added'], "Unexpected added in monitors-changed"
+
+    if verbose:
+        print('got expected change')
+
+    expected_change = None
+    loop.quit()
+
+def launch_observer():
+    global monitor_model
+
+    if verbose:
+        print('launch observer')
+
+    Gdk.set_allowed_backends('wayland')
+    display = Gdk.Display.open('gtk-test')
+
+    monitor_model = display.get_monitors()
+    assert monitor_model.get_n_items() == 0, "Unexpected initial monitors"
+    monitor_model.connect('items-changed', monitors_changed)
+
+def expect_monitors_changed(position, removed, added, timeout):
+    global expected_change
+    expected_change = {
+        'position' : position,
+        'removed' : removed,
+        'added' : added
+    }
+    wait(timeout)
+    assert expected_change == None, "Expected change did not happen"
+
+def got_connector(monitor, pspec):
+    loop.quit()
+
+def expect_monitor(position, width, height, scale, freq):
+    assert monitor_model.get_n_items() > position, f'Monitor {position} not present'
+    monitor = monitor_model.get_item(position)
+    if monitor.get_connector() == None:
+        handler = monitor.connect('notify::connector', got_connector)
+        wait(500)
+        monitor.disconnect(handler)
+    assert monitor.is_valid(), "Monitor is not valid"
+    geometry = monitor.get_geometry()
+    assert geometry.width == width, "Unexpected monitor width"
+    assert geometry.height == height, "Unexpected monitor height"
+    assert monitor.get_scale_factor() == scale, "Unexpected scale factor"
+    assert monitor.get_refresh_rate() == freq, "Unexpected monitor frequency"
+    if verbose:
+        print(f'monitor {position}: {geometry.width}x{geometry.height} frequency {monitor.get_refresh_rate()} scale {monitor.get_scale_factor()} model \'{monitor.get_model()}\' connector \'{monitor.get_connector()}\'')
+
+def run_commands():
+    try:
+        launch_observer()
+
+        add_monitor("0", width=100, height=100, scale=1, freq=60)
+        expect_monitors_changed(0, 0, 1, 1000)
+        expect_monitor (position=0, width=100, height=100, scale=1, freq=60000)
+
+        add_monitor("1", width=1024, height=768, scale=1, freq=144)
+        expect_monitors_changed(1, 0, 1, 1000)
+        expect_monitor (position=1, width=1024, height=768, scale=1, freq=144000)
+
+        remove_monitor("0")
+        expect_monitors_changed(0, 1, 0, 11000) # mutter takes 10 seconds to remove it
+
+        remove_monitor("1")
+        expect_monitors_changed(0, 1, 0, 11000)
+    except AssertionError as e:
+        print("Error: {0}".format(e))
+        terminate()
+
+def mutter_appeared(name):
+    global screen_cast
+    global done
+    if verbose:
+        print("mutter appeared on the bus")
+    screen_cast = bus.get('org.gnome.Mutter.ScreenCast',
+                          '/org/gnome/Mutter/ScreenCast')
+    run_commands()
+    done = True
+
+def mutter_vanished():
+    global done
+    if screen_cast != None:
+        if verbose:
+            print("mutter left the bus")
+        done = True
+
+bus = SessionBus()
+bus.watch_name('org.gnome.Mutter.ScreenCast', 0, mutter_appeared, mutter_vanished)
+
+try:
+    while not done:
+      GLib.MainContext.default().iteration(True)
+except KeyboardInterrupt:
+    print('Interrupted')

tests/run-headless-monitor-tests.sh

@@ -0,0 +1,26 @@
+#! /bin/sh
+
+builddir=$(pwd)/build
+
+dbus-run-session sh <<EOF
+
+# echo DBUS_SESSION_BUS_ADDRESS=\$DBUS_SESSION_BUS_ADDRESS
+# echo WAYLAND_DISPLAY=gtk-test
+
+mutter --headless --no-x11 --wayland-display gtk-test >&mutter.log &
+pid=\$!
+
+export WAYLAND_DISPLAY=gtk-test
+export GDK_BACKEND=wayland
+
+export GI_TYPELIB_PATH=$builddir/gtk:/usr/lib64/girepository-1.0
+export LD_PRELOAD=$builddir/gtk/libgtk-4.so
+
+python tests/headless-monitor-tests.py
+status=\$?
+
+kill \$pid
+
+exit \$status
+
+EOF