gtk3 a11y tests: Always use dbus-daemon for the AT-SPI bus

at-spi-bus-launcher launches a separate DBus instance for
AT-SPI, and prefers dbus-broker over dbus-daemon when the
corresponding build option was set and dbus-broker is present.

However, trying to launch a bus using dbus-broker fails
in the environment created for the gtk3 a11y tests, which
are run using `xvfb-run` and use a separate session bus
created using `dbus-launch`, (i.e. the dbus-daemon
implementation).

See [1] (and other messages of that email thread) and [2]
for more details.

Avoid the problem of mixing different DBus implementations
by setting an environment variable that makes at-spi-bus-launcher
use dbus-daemon instead of dbus-broker regardless of how
it was configured at build time.

This depends on at-spi2-core commit [3] for at-spi-bus-launcher
to actually evaluate the environment variable:

commit e735ed9135517532d37f7dab546786f8b4d39283
Author: Michael Weghorn <m.weghorn@posteo.de>
Date:   Wed Jul 31 11:27:27 2024 +0200

at-spi-bus-launcher: Introduce env var to select DBus implementation

In at-spi-bus-launcher, introduce evaluation
of an environment variable `ATSPI_DBUS_IMPLEMENTATION`
to allow explicitly overriding the DBus implementation
to use.

In case of `ATSPI_DBUS_IMPLEMENTATION=dbus-daemon`, don't try
to use dbus-broker, and vice versa.

This can e.g. be useful for tests in environments where
dbus-broker is installed and was configured as the
preferred DBus implementation at at-spi2-core build time,
but cannot be run in the test environment, e.g. when
tests are run via

xvfb-run --auto-servernum dbus-run-session [...]

Thanks to Colomban Wendling for mentioning that idea
in [1].

[1] https://gitlab.gnome.org/GNOME/at-spi2-core/-/issues/49#note_1854645

Related: #49

This makes

make CppunitTest_vcl_gtk3_a11y

pass on a current Fedora Rawhide when using a self-built at-spi2-core
from its git main branch.

[1] https://lists.freedesktop.org/archives/libreoffice/2023-August/090853.html
[2] https://gitlab.gnome.org/GNOME/at-spi2-core/-/issues/49
[3] https://gitlab.gnome.org/GNOME/at-spi2-core/-/commit/e735ed9135517532d37f7dab546786f8b4d39283

Change-Id: Ifd84ef1f993398423ac0e0f695c1c0323adf02b7
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/171366
Reviewed-by: Colomban Wendling <cwendling@hypra.fr>
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
Tested-by: Jenkins

0 files changed, 0 insertions, 0 deletions