GObject ╰── GTestDBus
A helper class for testing code which uses D-Bus without touching the user's session bus.
Note that GTestDBus modifies the user’s environment, calling
This is not thread-safe, so all GTestDBus calls should be completed before
threads are spawned, or should have appropriate locking to ensure no access
conflicts to environment variables shared between GTestDBus and other
Creating unit tests using GTestDBus
Testing of D-Bus services can be tricky because normally we only ever run D-Bus services over an existing instance of the D-Bus daemon thus we usually don't activate D-Bus services that are not yet installed into the target system. The GTestDBus object makes this easier for us by taking care of the lower level tasks such as running a private D-Bus daemon and looking up uninstalled services in customizable locations, typically in your source code tree.
The first thing you will need is a separate service description file for the
D-Bus daemon. Typically a
services subdirectory of your
is a good place to put this file.
The service file should list your service along with an absolute path to the
uninstalled service executable in your source tree. Using autotools we would
achieve this by adding a file such as
my-server.service.in in the services
directory and have it processed by configure.
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[D-BUS Service] Name=org.gtk.GDBus.Examples.ObjectManager Exec=@abs_top_builddir@/gio/tests/gdbus-example-objectmanager-server
You will also need to indicate this service directory in your test fixtures, so you will need to pass the path while compiling your test cases. Typically this is done with autotools with an added preprocessor flag specified to compile your tests such as:
Once you have a service definition file which is local to your source tree, you can proceed to set up a GTest fixture using the GTestDBus scaffolding.
An example of a test fixture for D-Bus services can be found here: gdbus-test-fixture.c
Note that these examples only deal with isolating the D-Bus aspect of your service. To successfully run isolated unit tests on your service you may need some additional modifications to your test case fixture. For example; if your service uses GSettings and installs a schema then it is important that your test service not load the schema in the ordinary installed location (chances are that your service and schema files are not yet installed, or worse; there is an older version of the schema file sitting in the install location).
Most of the time we can work around these obstacles using the
environment. Since the environment is inherited by the D-Bus daemon
created by GTestDBus and then in turn inherited by any services the
D-Bus daemon activates, using the setup routine for your fixture is
a practical place to help sandbox your runtime environment. For the
rather typical GSettings case we can work around this by setting
GSETTINGS_SCHEMA_DIR to the in tree directory holding your schemas
in the above
The GSettings schemas need to be locally pre-compiled for this to work. This can be achieved by compiling the schemas locally as a step before running test cases, an autotools setup might do the following in the directory holding schemas:
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all-am: $(GLIB_COMPILE_SCHEMAS) . CLEANFILES += gschemas.compiled
Create a new GTestDBus object.
a new GTestDBus.
Get the flags of the GTestDBus object.
the value of “flags” property
the address of the bus, or
Add a path where dbus-daemon will look up .service files. This can't be
path to a directory containing .service files
Start a dbus-daemon instance and set DBUS_SESSION_BUS_ADDRESS. After this call, it is safe for unit tests to start sending messages on the session bus.
Stop the session bus started by
g_test_dbus_down(), this won't verify the GDBusConnection
singleton returned by
g_bus_get_sync() is destroyed. Unit
tests wanting to verify behaviour after the session bus has been stopped
can use this function but should still call
g_test_dbus_down() when done.
Stop the session bus started by
Unset DISPLAY and DBUS_SESSION_BUS_ADDRESS env variables to ensure the test won't use user's session bus.
This is useful for unit tests that want to verify behaviour when no session
bus is running. It is not necessary to call this if unit test already calls
g_test_dbus_up() before acquiring the session bus.
Types and Values
typedef struct _GTestDBus GTestDBus;
The GTestDBus structure contains only private data and should only be accessed using the provided API.