This reverts commit 4aba03562b, preserving
the new tests but adjusting them to assert that the old behaviour is
restored.
As expected, there were a few projects which broke because of this.
Unfortunately, in one case the breakage crosses a project boundary:
sysprof ships D-Bus introspection XML, which is consumed by mutter and
passed through gdbus-codegen.
Since sysprof cannot add this annotation without breaking its existing
users, a warning is also not appropriate.
https://gitlab.gnome.org/GNOME/jhbuild/issues/41https://gitlab.gnome.org/GNOME/sysprof/issues/17https://gitlab.gnome.org/GNOME/glib/issues/1726
Skip it on systems which don’t support it, rather than compiling it out.
That gives us more information from test runs about which tests are
being run on which architectures.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Currently, there is no quick way to find whether and element is already
part of a list store, except for manually writing a for-loop and calling
`g_list_model_get_item()` and breaking when you find the item.
This is mostly just a small API addition to support this use case.
Fixes https://gitlab.gnome.org/GNOME/glib/issues/1011
When compiling GLib with `-Wsign-conversion`, we get various warnings
about the atomic calls. A lot of these were fixed by
3ad375a629, but some remain. Fix them by
adding appropriate casts at the call sites.
Note that `g_atomic_int_{and,or,xor}()` actually all operate on `guint`s
rather than `gint`s (which is what the rest of the `g_atomic_int_*()`
functions operate on). I can’t find any written reasoning for this, but
assume that it’s because signedness is irrelevant when you’re using an
integer as a bit field. It’s unfortunate that they’re named a
`g_atomic_int_*()` rather than `g_atomic_uint_*()` functions.
Tested by compiling GLib as:
```
CFLAGS=-Wsign-conversion jhbuild make -ac |& grep atomic
```
I’m not going to add `-Wsign-conversion` to the set of default warnings
for building GLib, because it mostly produces false positives throughout
the rest of GLib.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #1565
They provide more detailed failure messages, and aren’t compiled out
when building with `G_DISABLE_ASSERT`.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Previously, if a method was not annotated with org.gtk.GDBus.C.UnixFD
then the generated code would never contain GUnixFDList parameters, even
if the method has 'h' (file descriptor) parameters. However, in this
case, the generated code is essentially useless: the method cannot be
called or handled except in degenerate cases where the file descriptors
are missing or ignored.
Check the argument types for 'h', and if present, generate code as if
org.gtk.GDBus.C.UnixFD annotation were specified.
This change will break any existing code which refers to the (useless)
wrappers for such methods. The workaround for such code is to add the
org.gtk.GDBus.C.UnixFD annotation, which will cause the same generated
code to be emitted before and after this change.
If this is found to cause widespread problems, we can explore a
different approach (perhaps emitting a warning from the code generator,
or annotating the symbols as deprecated).
https://gitlab.gnome.org/GNOME/glib/issues/1726
Instead of letting each directory to find its way to link with libdl,
it is easier to put the check in the top level, so its result can be
used by all directories.
It is a follow-up of https://gitlab.gnome.org/GNOME/glib/merge_requests/810.
When resetting a key in the delayed settings backend,
g_settings_backend_changed() was not called to notify the backend of
the change.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #1309
We're using the `install` argument for configure_file() all over the
place.
The support for an `install` argument for configure_file() was added in
Meson 0.50, but we haven't bumped the minimum version of Meson we
require, yet; which means we're getting compatibility warnings when
using recent versions of Meson, and undefined behaviour when using older
versions.
The configure_file() object defaults to `install: false`, unless an
install directory is used. This means that all instances of an `install`
argument with an explicit `true` or `false` value can be removed,
whereas all instances of `install` with a value determined from a
configuration option must be turned into an explicit conditional.
The plugin modules in these tests get statically linked with a separate
copy of GLib so they end up calling vfuncs in their own copy of GLib.
Fixes#1648
We need to enable building the dirent and gnulib sources for clang-cl,
as we are still using the Microsoft-style headers and lib's and CRT.
We need to also do this for the following, for similar reasoning:
-Symbol export (via __declspec(dllexport))
-Dependency discovery without pkg-config files
-long long and ssize_t detection
We do, however, enable the autoptr tests for clang-cl builds. Note that
at this point real MSVC builds are still better supported than clang-cl
builds, and it will likely remain so for at least the near future,
alhtough real MSVC builds of the GTK stack are consumable and are usable
by clang-cl.
Now that we're not calling g_object_run_dispose() indirectly in
g_test_dbus_down() (see commit "Revert "gtestdbus: Properly close server
connections""), the test gdbus-connection-loss is failing with the
message "Bail out! GLib-GIO-FATAL-WARNING: Weak notify timeout, object
ref_count=1". This is because we're holding a reference to the singleton
connection object while calling session_bus_down() in the test's main().
So then we end up waiting for 30 seconds in
_g_object_unref_and_wait_weak_notify() for the GWeakNotify to be
triggered, which never happens.
The fix is to unref the connection before calling session_bus_down().
This is consistent with how other tests work, and is safe because the
only method called on the connection has already errored out, as
asserted by the test.
This reverts commit c37cd19fee.
Now that we've reverted the commit "gtestdbus: Properly close server
connections", g_test_dbus_down() no longer returns early and we no
longer need this workaround. Since the gdbus-names test seems to
properly unref its GDBusConnection objects it's not clear to me why it
needed the sleep to succeed. However even at the time the failure wasn't
reproducible according to this comment[1] so it's probably not worth
spending more effort trying to reproduce it now.
[1] https://gitlab.gnome.org/GNOME/glib/issues/787#note_214235
There seems to be no reason to do so, and since the `appinfo` test was
ported to use `G_TEST_OPTION_ISOLATE_DIRS`, it has been causing
coredumps to accumulate. `gnome-terminal` was chosen as the terminal,
but it couldn’t find its GSettings schemas due to all the XDG
environment variables being cleared to `/dev/null` by
`G_TEST_OPTION_ISOLATE_DIRS`.
In order to keep using `gnome-terminal` as a subprocess in the tests,
we’d need to explicitly set up its environment so it can load the right
GSettings schemas. That’s a lot of work for not much gain.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #436
On Visual Studio, Meson builds modules as xxxx.dll, not libxxxx.dll when
xxxx is specified as the name for the shared_module() build directive.
This means that in the test programs if we expect for libxxxx for the
module name, the test will fail as there is no libxxxx.dll but there is
xxxx.dll. This makes the test program look for the module files
correctly.
This ensures that D-Bus connections established with unix:dir and
unix:path addresses actually work properly. Previously, we only tested
unix:tmpdir and TCP addresses.
unix:dir= addresses are exactly the same as unix:tmpdir= addresses,
already supported by GDBus, except they forbid use of abstract sockets.
This is convenient for situations where abstract sockets are
impermissible, such as when a D-Bus client inside a network namespace
needs to connect to a server running in a different network namespace.
An abstract socket cannot be shared between two processes in different
network namespaces.
Applications could use unix:path= addresses instead, so this is only a
convenience, but there's no good reason not to support unix:dir=.
Currently it is not supported simply because unix:dir= is a relatively
recent addition to the D-Bus spec.
It's somewhat unrealistic to use a GDBusServer without a
GDBusAuthObserver, because most D-Bus servers want to be like the
standard session bus (the owning user can connect) rather than being
like the standard system bus (all users can connect, the server is a
security boundary, and many bugs are security vulnerabilities).
Signed-off-by: Simon McVittie <smcv@collabora.com>
Previously, its tests were being run in the build directory, which is
fine (it should always be writable). If multiple tests were run in
parallel, for example with Meson’s `--repeat` option, their test files
would collide.
Fix that by running each test instance in a separate subdirectory of
`/tmp`.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #1634
Add a case for when the IPv6 result comes back negative and the IPv4
result is significantly delayed. This is exactly the case that causes
the bug addressed by GNOME/glib!865
It should produce a generic result, but not crash. It was previously
crashing on macOS.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #1729
g_assert_*() give more helpful error messages on failure, and aren’t
compiled out by G_DISABLE_ASSERT.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
This was introduced in commit 7846d6154a: g_subprocess_get_identifier()
will return NULL after the subprocess has exited, and the subprocess in
the `noop` test will exit as soon as it has started spawning. So if the
scheduler scheduled the testprog subprocess quickly, descheduled the
parent test process until the testprog exited, then the return value
from g_subprocess_get_identifier() would be NULL.
Move the g_subprocess_get_identifier() test to one which calls testprog
in `sleep-forever` mode, since that is guaranteed not to exit until
killed (which we do later in the test).
Signed-off-by: Philip Withnall <withnall@endlessm.com>
The parent GNetworkAddress contains a shared list of resolved
addresses that is used as a cache for multiple enumerations.
This commit ensures that the cache is only set upon completion of
DNS lookups and only read once by enumerations to avoid being in a
bad state.
Fixes#1771
Some of these have a negative master/slave connotation, and they add no
value. Change or drop them.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
The `monitor` test was originally written to test GFileMonitor with
directories. Over time, `testfilemonitor` acquired units for testing
directories as well, which made the `monitor` test reduntant.
Other GCC-like implementations of ld/objcopy (like LLVM) don’t yet
support the right command line arguments, so can’t compile the test.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
https://gitlab.gnome.org/GNOME/glib/issues/1709
This introduces no functional changes, but combines two duplicated lists
and makes the meson.build file a little easier to follow.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #1711
After repeated local testing, I can’t reproduce failures with them:
meson test --repeat 5000 gdbus-auth
meson test --repeat 5000 gdbus-bz627724
meson test --repeat 5000 gdbus-connection
The FreeBSD failures from pthread calls mentioned in #1614 should
probably manifest as use-after-free for GMutex or pthread_mutex_t on
Linux. Failing that, I haven’t seen any relevant FreeBSD failures on CI
for at least a month, so if it’s not fixed, the chances of debugging are
very low.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
https://gitlab.gnome.org/GNOME/glib/issues/1614
Check for RTLD_NEXT being present, and disable the gsocketclient-slow
test if it's absent, since the shlib dependency of that test requires
RTLD_NEXT to function.
This allows the testsuite to be built on Cygwin, which behaves
exactly like UNIX, but doesn't have RTLD_NEXT.
Just skip the test if the unix transport isn’t supported. This means we
get better compilation coverage, and more explicit TAP output saying
that the test is being skipped on unsupported platforms.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
The test performs implicit autolaunching of a bus
and checks if it is connectible.
In build the test is moved from "only non-windows with have_dbus_daemon"
to "anywhere".
This is intentional: actually it doesn't execute any external
binaries on unix (so doesn't require dbus_daemon)
and now has win32 implementation.
The test has some problems that are not problems of test itself,
but are reasoned by current win32 implementation:
- since the implementation uses global win32 kernel objects
with fixed names not depending on g_get_user_runtime_dir or other context
if preexisting bus running by some other libgio-using application
the test would silently pass.
- since the implementation uses problematic time-based synchronization,
that has a race condition between opening and reading mmaped address,
the test may randomly fail (I'd not seen this in practice).
- since the implementation autolaunched process works for 3 seconds
after last client disconnects, the executed subprocess runs for 3 seconds
after test exit, maybe locking the libgio-2.0-0.dll file for that time.
g_assert_*() give more informative failure messages, and aren’t compiled
out when building with G_DISABLE_ASSERT.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
g_assert_*() give more informative failure messages, and aren’t compiled
out when building with G_DISABLE_ASSERT.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
In order to allow GLib itself to be built with G_DISABLE_ASSERT defined,
we need to explicitly undefine it when building the tests, otherwise
g_test_init() turns into an abort.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #1708
g_assert_*() give more informative error messages on failure, and can’t
be disabled by G_DISABLE_ASSERT.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Commit f975858e86 removed the NULL check in g_cancellable_cancel() by
accident which makes it crash when called with NULL.
Add the check back and add a test so this doesn't happen again.
Fixes#1710
Don’t pollute the build directory with files generated by running the
test.
Note that there are still other tests in the gsettings.c test suite
which use the build directory, but fixing them is a bit more involved
than I have time for right now. This is a step in the right direction.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
This essentially reverts commit
cffed58737.
The preceding two commits have fixed the test so it’s no longer flaky.
The following command gives 5000 passes in a row for me:
meson test -C /opt/gnome/build/glib/ socket-service --repeat 5000
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Fixes: #1679
It’s occasionally possible for the cancellation of the service to happen
before connection_cb() gets scheduled in the other thread. The
locking/unlocking order of mutex_712570 requires:
• test_threaded_712570(): lock mutex
• test_threaded_712570(): start wait loop
• connection_cb(): lock mutex
• test_threaded_socket_service_finalize(): unlock mutex
• test_threaded_712570(): end wait loop
• test_threaded_712570(): unlock mutex
Fix that by quitting the main loop once connection_cb() has been called
(i.e. once the server thread has received the incoming connection
request), rather than just after the client thread (main thread) has
sent a connection request.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #1679
On about 1 in 3 test runs, the socket-service would fail with the
ref_count assertion in connection_cb() failing (the ref_count would be 3
rather than the expected 2).
This was happening because the GTask from
g_socket_listener_accept_socket_async() now always takes at least one
main context iteration to return a result (whereas before
6f3d57d2ee it might have taken zero), but
the ref_count can drop below 3 before the process of returning a result
starts. During the process of returning a result, the ref_count
temporarily increases again, which is what was breaking the test.
Fix this by waiting for one more main context iteration. This is a bit
of a hack, but the real fix would be to expose the outstanding_accept
boolean from GSocketService as public API (which the test can
interrogate), and that seems too much like exposing internal state.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Helps: #1679
Compilers get confused when variables are initialized by a function by
taking them as reference in an out argument; this, coupled with the fact
that C does not initialize variables by default, most commonly results
in a "maybe uninitialized" compiler warning.
When testing as root, changing the permissions of the keyfile will have
no effect on the writability since root bypasses these permissions. See
path_resolution(7). Skip the test in this case.
g_assert_*() give more informative error messages, and aren’t compiled
out when building with G_DISABLE_ASSERT.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
getsockname() returns the address that the socket was bound to.
If it was bound to INADDR_ANY, getsockname() will stubbornly return INADDR_ANY
(and someport - that one is valid).
Subsequent connection attempts to INADDR_ANY:someport will fail with winsock.
Actually, it doesn't make even sense to connect to INADDR_ANY at all
(where is the socket connecting to? To a random interface of the host?),
so this is just a straight-up change, without platform-specific ifdefing.
Use loopback instead of INADDR_ANY. To ensure that binding and creation
of INADDR_ANY is still tested, use two addresses: bind to INADDR_ANY,
but connect to loopback, with the port number that we got from the bound
address.
The gsocketclient-slow test needs this, otherwise connect() succeeds
immeidately and the test fails, because it is checking that cancellation
works. We weren't installing it for installed tests.
It's necessary sometimes for installed tests to be able to run with a
custom environment. For example, the gsocketclient-slow test requires an
LD_PRELOADed library to provide a slow connect() (this is to be added in
a followup commit).
Introduce a variable `@env@` into the installed test template, which we
can override as necessary when generating `.test` files, to run tests
prefixed with `/usr/bin/env <LIST OF VARIABLES>`.
As the only test that requires this currently lives in `gio/tests/`, we
are only hooking this up for that directory right now. If other tests in
future require this treatment, then the support can be extended at that
point.
There's no /tmp directory on Windows.
Use g_get_tmp_dir(), and adjust the test to work with that.
The test *still* checks the basename of the new CWD, it just
doesn't need to be "tmp" anymore.
envp in spawn() functions is the *whole* environment table
for the child process. Including PATH. Thus, unless PATH is explicitly
put into that table, the process will be spawned without PATH.
Since on Windows binaries are found via PATH instead of LD_LIBRARY_PATH
or whatever, almost no program (unless installed in WINDIR, maybe)
can run without a PATH. Certainly not test programs - meson
adds bld subdirs to the PATH to make sure that test programs
use uninstalled glib at runtime.
So make sure that PATH is passed along.
Windows \r\n EOLs strike again. The test already knows about LINEEND,
so make it use LINEEND more (instead of swithcing pipes
to binary mode). This also applies to counting the bytes
read.
With winsock sending messages to NULL results in G_IO_ERROR_NOT_CONNECTED
instead of G_IO_ERROR_FAILED.
MSDN says:
WSAENOTCONN
10057
Socket is not connected.
A request to send or receive data was disallowed because the socket is not connected
and (when sending on a datagram socket using sendto) no address was supplied.
So this is a direct mapping of the implementation error.
Covering it up in the wrapper (by converting it to G_IO_ERROR_FAILED)
doesn't seem feasible or needed (no one, except for the testsuite,
really cares which unrecoverable error is returned by sendto()).
getaddrinfo() in winsock can't understand scope IDs.
There's no obvious way to fix that, short of re-implementing
that function, so disable that part of the test on Windows.
Previously once the end of addresses was reached it would return
NULL even if it was waiting on a dns response. Now it will keep
waiting so all addresses are received.
Fixes#1680
Currently, the actual asynchronous work, represented by
asynchronous_cancellation_run_task, was over before the GCancellable
could be triggered. While that doesn't invalidate the purpose of the
test, since it's fundamentally about cancellation, it would be
nicer if the cancellation actually served some purpose instead of
being a mere formality.
https://gitlab.gnome.org/GNOME/glib/issues/1608
It needs investigating and fixing properly, but let’s not let it disrupt
the CI in the meantime.
Follow-up in https://gitlab.gnome.org/GNOME/glib/issues/1679.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
In the writev() tests, the handling of cancellation is tested. However,
the GCancellable was cancelled after the writev_async() call was
started. Depending on the implementation of the writev() vfunc, the
operation could be done in a thread or in callbacks on the current
thread’s main loop. If done in a separate thread, there’s a chance that
enough of the write could happen before cancellation reaches that thread
that the overall operation returns success with a short write.
That would cause the test to fail, sometimes.
Avoid that by cancelling the GCancellable before starting the writev()
operation.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Reviewed-by: nobody
It would always be initialized but initialize it to NULL to silence the
compiler, and also check that it is not NULL anymore when we expect it
to contain a valid value.
../gio/tests/desktop-app-info.c: In function ‘test_fallback’:
../gio/tests/desktop-app-info.c:191:18: warning: ‘app’ may be used uninitialized in this function [-Wmaybe-uninitialized]
g_assert_true (g_app_info_equal (info1, app));
^~~~~~~~~~~~~~~~
It needs investigating and fixing properly, but let’s not let it disrupt
the CI in the meantime.
Follow-up in https://gitlab.gnome.org/GNOME/glib/issues/1653.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
There's a race here, as revealed by Debian's buildds.
We call g_dbus_proxy_new() to create a proxy for the test server, with
callback proxy_ready() Then we call g_spawn_command_line_async() to
start the test server, and then start the main loop.
proxy_ready() assumes that the test server hasn't been started when it
is called. But there is no guarantee that these asynchronous operations
involving spawning a process won't happen in a different order that mean
the bus name *does* have an owner.
What we can do is move starting the server inside of proxy_ready(), so
we know that the test server isn't started until after the proxy is
created. We also add an assertion to check that it is indeed not running
before we execute it.
If we can't find the mount point for target or tmp (as currently
happens on Launchpad autobuilders, and perhaps relatedly, on a
development system that uses btrfs), that's probably not great but is
not really the point of this test.
Signed-off-by: Simon McVittie <smcv@collabora.com>
In a minimal autobuilder environment, this test could conceivably be
the first thing to refer to ~/.local.
Modified by Iain Lane <laney@debian.org>: Don't try to create ~/.local
from tests, but skip if it doesn't exist.
Signed-off-by: Simon McVittie <smcv@collabora.com>
So long, and thanks for everything. We’re a Meson-only shop now.
glib-2-58 will remain the last stable GLib release series which is
buildable using autotools.
We continue to install autoconf macros for autotools-using projects
which depend on GLib; they are stable API.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
Calling
g_list_model_get_item (store, 0);
g_list_model_get_item (store, -1u);
does not return NULL for the second call, as it should.
This was showing up in GTK+ list model tests.
Add option to not encode resource data into the C source file
in order to embed the data using `ld -b binary`. This improves compilation
times, but can only be done on Linux or other platforms with a
supporting linker.
(Rebased by Philip Withnall, fixing minor rebase conflicts.)
Fixes#1489
This reverts commit 52bab0254a.
It silently conflicted with another commit,
90ca3b4dd0, which was merged later than
it. I’ve kept commit 90ca3b because it also frees the GError; 52bab
doesn’t.
This is my failure to rebase and test old branches before merging them,
instead of assuming that the lack of automatically detected merge
conflicts actually means there are no merge conflicts.
Allow any type of private key in PEM files by treating PEM guards ending
with "PRIVATE KEY-----" as a private key instead of looking for a
pre-defined set of PEM guards. This enables the possibility for custom
GTlsBackend to add support for new key types.
Test cases have been expanded to ensure PEM parsing works for private
key when either header or footer is missing.
Encrypted PKCS#8 is still rejected. Test case has been added for this to
ensure behaviour is the same before and after this change.
The `apps` subprocess is spawned by desktop-app-info to interpret the
forest of .desktop files, and its output is provided on stdout. If debug
output is mixed up with that output, tests which parse the output fail.
Disable the debug output from the subprocess to prevent this.
The new debug output appeared as a result of recent changes to the
desktop file dir monitoring code in gdesktopappinfo.c.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
The appinfo-test.desktop file is set up with an Exec= path which points
to the compiled and installed appinfo-test utility. When running the
tests uninstalled, however, this might not be present, which causes
loading appinfo-test.desktop to fail.
Split appinfo-test.desktop in two: keep the existing
appinfo-test.desktop for tests which need to launch appinfo-test, and
add a new appinfo-test-static.desktop for tests which don’t launch
anything (and, for example, just inspect GAppInfo properties).
appinfo-test-static.desktop uses an Exec= line which should always be
present (`true`) so it should never fail to load.
Allow the tests using appinfo-test-static.desktop to be run uninstalled
or installed. Allow the tests using appinfo-test.desktop to be skipped
if loading appinfo-test.desktop fails, which is an indicator that the
test is running uninstalled.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
g_assert() is for runtime code, and can be compiled out. g_assert_*()
cannot be compiled out, and give more helpful failure messages for
specific types.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
g_assert() can be compiled out with G_DISABLE_ASSERT, which renders the
test useless. The g_assert_*() functions provide more helpful feedback
on failure too.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
By encoding the path to the appinfo-test binary in the .desktop files,
we can avoid a chdir() call in the tests, which was a bit ugly.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
https://gitlab.gnome.org/GNOME/glib/issues/538
This partially reverts commit 27b5fb5892.
The infrastructure for disabling a test is kept, but the appinfo and
desktop-app-info tests no longer need to be run serially.
Signed-off-by: Philip Withnall <withnall@endlessm.com>
https://gitlab.gnome.org/GNOME/glib/issues/1601
This checks if the stream is writable before writing
to it. If the write succeeded with no error, then the
stream has to be also writable after the write
As RFC 8305 recommends we can start multiple DNS queries in parallel
to more quickly make an initial response, especially when one is
particularly slow/broken.
This is to ensure that the generated code is still compilable by the
running compiler, and see whether we can read the things in there
properly.
See issue #1580.
