Features/QTest

Summary

QTest is an internal framework used in the QEMU unit tests. A QTest based test will spin up one or more QEMU binaries and orchestrate the test via a qtest control socket. The binaries themselves are usually controlled using a QMP socket to trigger events.

Debugging

Usually the first problem a new developer comes across is understanding how a test fails. The qtest tests are all grouped together by target architectures so the first step is to re-run make check for the particular architecture that failed:

   make check-qtest-i386 V=1

The test run will now dump a lot more information about how the test is run. This will be a gtester call with a large number of tests included. This can then be repeated with just the tests you want. For example:

   QTEST_QEMU_BINARY=i386-softmmu/qemu-system-i386 QTEST_QEMU_IMG=qemu-img MALLOC_PERTURB_=${MALLOC_PERTURB_:-$((RANDOM % 255 + 1))} gtester -k --verbose -m=quick tests tests/vhost-user-test

For additional information you can set QTEST_LOG and also use qtester -p to specify the subtest you want to run:

   QTEST_LOG=1 QTEST_QEMU_BINARY=i386-softmmu/qemu-system-i386 QTEST_QEMU_IMG=qemu-img MALLOC_PERTURB_=${MALLOC_PERTURB_:-$((RANDOM % 255 + 1))} gtester -k --verbose -m=quick tests/vhost-user-test -p /i386/vhost-user/migrate

Implementation

Please see tests/libqtest.h for device test APIs. Search the tests/ directory for examples using libqtest.