From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49753) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dYUKj-0002Ut-Tb for qemu-devel@nongnu.org; Fri, 21 Jul 2017 05:34:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dYUKi-0008Et-Pm for qemu-devel@nongnu.org; Fri, 21 Jul 2017 05:34:53 -0400 From: Stefan Hajnoczi Date: Fri, 21 Jul 2017 10:34:16 +0100 Message-Id: <20170721093416.17816-1-stefanha@redhat.com> Subject: [Qemu-devel] [PATCH] qemu-iotests: add a "how to" to ./README List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, Stefan Hajnoczi , Ishani Chugh There is not much getting started documentation for qemu-iotests. This patch explains how to create a new test and covers the overall testing approach. Cc: Ishani Chugh Signed-off-by: Stefan Hajnoczi --- tests/qemu-iotests/README | 83 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) diff --git a/tests/qemu-iotests/README b/tests/qemu-iotests/README index 6079b40..8259b9f 100644 --- a/tests/qemu-iotests/README +++ b/tests/qemu-iotests/README @@ -14,8 +14,91 @@ Just run ./check to run all tests for the raw image format, or ./check -qcow2 to test the qcow2 image format. The output of ./check -h explains additional options to test further image formats or I/O methods. +* Testing approach + +Each test is an executable file (usually a bash script) that is run by the +./check test harness. Standard out and standard error are captured to an +output file. If the output file differs from the "golden master" output file +for the test then it fails. + +Tests are simply a sequence of commands that produce output and the test itself +does not judge whether it passed or failed. If you find yourself writing +checks to determine success or failure then you should rethink the test and +rely on output diffing instead. + +** Filtering volatile output + +When output contains absolute file paths, timestamps, process IDs, hostnames, +or other volatile strings, the diff against golden master output will fail. +Such output must be filtered to replace volatile strings with fixed +placeholders. + +For example, the path to the temporary working directory changes between test +runs so it must be filtered: + + sed -e "s#$TEST_DIR/#TEST_DIR/#g" + +Commonly needed filters are available in ./common.filter. + +** Python tests + +Most tests are implemented in bash but it is difficult to interact with the QMP +monitor. A Python module called 'iotests' is available for tests that require +JSON and interacting with QEMU. + +* How to create a test + +1. Choose an unused test number + +Tests are identified by a unique number. Look for the highest test case number +by looking at the test files. Then search the qemu-devel@nongnu.org mailing +list to check if anyone has already sent patches using the next available +number. You may need to increment the number a few times to reach an unused +number. + +2. Create the test file + +Copy an existing test (one that most closely resembles what you wish to test) +to the new test number: + + cp 001 + +3. Assign groups to the test + +Add your test to the ./group file. This file is the index of tests and assigns +them to functional groups like "rw" for read-write tests. Most tests belong to +the "rw" and "auto" groups. "auto" means the test runs when ./check is invoked +without a -g argument. + +Consider adding your test to the "quick" group if it executes quickly (<1s). +This group is run by "make check-block" and is often included as part of build +tests in continuous integration systems. + +4. Write the test + +Edit the test script. Look at existing tests for examples. + +5. Generate the golden master file + +Run your test with "./check ". You may need to pass additional +options to use an image format or protocol. + +The test will fail because there is no golden master yet. Inspect the output +that your test generated with "cat .out.bad". + +Verify that the output is as expected and contains no volatile strings like +timestamps. You may need to add filters to your test to remove volatile +strings. + +Once you are happy with the test output it can be used as the golden master +with "mv .out.bad .out". Rerun the test to verify +that it passes. + +Congratulations, you've created a new test! + * Feedback and patches Please send improvements to the test suite, general feedback or just reports of failing tests cases to qemu-devel@nongnu.org with a CC: to qemu-block@nongnu.org. + -- 2.9.4