tests/functional: enable pre-emptive caching of assets

Many tests need to access assets stored on remote sites. We don't want
to download these during test execution when run by meson, since this
risks hitting test timeouts when data transfers are slow.

Add support for pre-emptive caching of assets by setting the env var
QEMU_TEST_PRECACHE to point to a timestamp file. When this is set,
instead of running the test, the assets will be downloaded and saved
to the cache, then the timestamp file created.

A meson custom target is created as a dependency of each test suite
to trigger the pre-emptive caching logic before the test runs.

When run in caching mode, it will locate assets by looking for class
level variables with a name prefix "ASSET_", and type "Asset".

At the ninja level

   ninja test --suite functional

will speculatively download any assets that are not already cached,
so it is advisable to set a timeout multiplier.

   QEMU_TEST_NO_DOWNLOAD=1 ninja test --suite functional

will fail the test if a required asset is not already cached

   ninja precache-functional

will download and cache all assets required by the functional
tests

At the make level, precaching is always done by

   make check-functional

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Tested-by: Richard Henderson <richard.henderson@linaro.org>
[thuth: Remove the duplicated "path = os.path.basename(...)" line]
Message-ID: <20240830133841.142644-16-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/tests/functional/qemu_test/testcase.py b/tests/functional/qemu_test/testcase.py
index b2dd863c6e..18314be9d1 100644
--- a/tests/functional/qemu_test/testcase.py
+++ b/tests/functional/qemu_test/testcase.py
@@ -21,6 +21,7 @@ import uuid
 from qemu.machine import QEMUMachine
 from qemu.utils import kvm_available, tcg_available
 
+from .asset import Asset
 from .cmd import run_cmd
 from .config import BUILD_DIR
 
@@ -58,6 +59,12 @@ class QemuBaseTest(unittest.TestCase):
 
     def main():
         path = os.path.basename(sys.argv[0])[:-3]
+
+        cache = os.environ.get("QEMU_TEST_PRECACHE", None)
+        if cache is not None:
+            Asset.precache_suites(path, cache)
+            return
+
         tr = pycotap.TAPTestRunner(message_log = pycotap.LogMode.LogToError,
                                    test_output_log = pycotap.LogMode.LogToError)
         unittest.main(module = None, testRunner = tr, argv=["__dummy__", path])