Tempest Test Removal Procedure

Historically, Tempest was the only way of doing functional testing and integration testing in OpenStack. This was mostly only an artifact of Tempest being the only proven pattern for doing this, not an artifact of a design decision. However, moving forward, as functional testing is being spun up in each individual project, we really only want Tempest to be the integration test suite it was intended to be: testing the high-level interactions between projects through REST API requests. In this model, there are probably existing tests that aren’t the best fit living in Tempest. However, since Tempest is largely still the only gating test suite in this space we can’t carelessly rip out everything from the tree. This document outlines the procedure which was developed to ensure we minimize the risk for removing something of value from the Tempest tree.

This procedure might seem overly conservative and slow-paced, but this is by design to try to ensure we don’t remove something that is actually providing value. Having potential duplication between testing is not a big deal especially compared to the alternative of removing something which is actually providing value and is actively catching bugs, or blocking incorrect patches from landing.

Proposing a test removal

3 prong rule for removal

In the proposal etherpad we’ll be looking for answers to 3 questions:

  1. The tests proposed for removal must have equiv. coverage in a different project’s test suite (whether this is another gating test project, or an in tree functional test suite). For API tests preferably the other project will have a similar source of friction in place to prevent breaking API changes so that we don’t regress and let breaking API changes slip through the gate.

  2. The test proposed for removal has a failure rate < 0.50% in the gate over the past release (the value and interval will likely be adjusted in the future)

  3. There must not be an external user/consumer of Tempest that depends on the test proposed for removal

The answers to 1 and 2 are easy to verify. For 1 just provide a link to the new test location. If you are linking to the Tempest removal patch please also put a Depends-On in the commit message for the commit which moved the test into another repo.

For prong 2 you can use subunit2sql:

Using subunit2sql directly

SELECT * from tests where test_id like "%test_id%"; (where $test_id is the full test_id, but truncated to the class because of setUpClass or tearDownClass failures)

You can access the infra mysql subunit2sql db w/ read-only permissions with:

  • hostname: logstash.openstack.org

  • username: query

  • password: query

  • db_name: subunit2sql

For example if you were trying to remove the test with the id: tempest.api.compute.admin.test_flavors_negative.FlavorsAdminNegativeTestJSON.test_get_flavor_details_for_deleted_flavor you would run the following:

  1. run the command: mysql -u query -p -h logstash.openstack.org subunit2sql to connect to the subunit2sql db

  2. run the query:

    MySQL [subunit2sql]> select * from tests where test_id like \
"tempest.api.compute.admin.test_flavors_negative.FlavorsAdminNegativeTestJSON%";

    which will return a table of all the tests in the class (but it will also catch failures in setUpClass and tearDownClass)

  3. paste the output table with numbers and the mysql command you ran to generate it into the etherpad.

Eventually, a CLI interface will be created to make that a bit more friendly. Also a dashboard is in the works so we don’t need to manually run the command.

The intent of the 2nd prong is to verify that moving the test into a project specific testing is preventing bugs (assuming the Tempest tests were catching issues) from bubbling up a layer into Tempest jobs. If we’re seeing failure rates above a certain threshold in the gate checks that means the functional testing isn’t really being effective in catching that bug (and therefore blocking it from landing) and having the testing run in Tempest still has value.

However, for the 3rd prong verification is a bit more subjective. The original intent of this prong was mostly for interop/refstack and also for things that running on the stable branches. We don’t want to remove any tests if that would break our API consistency checking between releases, or something that interop/refstack is depending on being in Tempest. It’s worth pointing out that if a test is used in interop_wg as part of interop testing then it will probably have continuing value being in Tempest as part of the integration/integrated tests in general. This is one area where some overlap is expected between testing in projects and Tempest, which is not a bad thing.

Discussing the 3rd prong

There are 2 approaches to addressing the 3rd prong. Either it can be raised during a QA meeting during the Tempest discussion. Please put it on the agenda well ahead of the scheduled meeting. Since the meeting time will be well known ahead of time anyone who depends on the tests will have ample time beforehand to outline any concerns on the before the meeting. To give ample time for people to respond to removal proposals please add things to the agenda by the Monday before the meeting.

The other option is to raise the removal on the openstack-discuss mailing list. (for example see: http://lists.openstack.org/pipermail/openstack-dev/2016-February/086218.html or http://lists.openstack.org/pipermail/openstack-discuss/2019-March/003574.html ) This will raise the issue to the wider community and attract at least the same (most likely more) attention than discussing it during the irc meeting. The only downside is that it might take more time to get a response, given the nature of ML.

Exceptions to this procedure

For the most part, all Tempest test removals have to go through this procedure there are a couple of exceptions though:

  1. The class of testing has been decided to be outside the scope of Tempest.

  2. A revert for a patch which added a broken test, or testing which didn’t actually run in the gate (basically any revert for something which shouldn’t have been added)

  3. Tests that would become out of scope as a consequence of an API change, as described in API Compatibility. Such tests cannot live in Tempest because of the branchless nature of Tempest. Such tests must still honor prong #3.

For the first exception type, the only types of testing in the tree which have been declared out of scope at this point are:

  • The CLI tests (which should be completely removed at this point)

  • Neutron Adv. Services testing (which should be completely removed at this point)

  • XML API Tests (which should be completely removed at this point)

  • EC2 API/boto tests (which should be completely removed at this point)

For tests that fit into this category, the only criteria for removal is that there is equivalent testing elsewhere.

Tempest Scope

Starting in the liberty cycle Tempest, has defined a set of projects which are defined as in scope for direct testing in Tempest. As of today that list is:

  • Keystone

  • Nova

  • Glance

  • Cinder

  • Neutron

  • Swift

Anything that lives in Tempest which doesn’t test one of these projects can be removed assuming there is equivalent testing elsewhere. Preferably using the tempest plugin mechanism to maintain continuity after migrating the tests out of Tempest.

API Compatibility

If an API introduces a non-discoverable, backward-incompatible change, and such a change is not backported to all versions supported by Tempest, tests for that API cannot live in Tempest anymore. This is because tests would not be able to know or control which API response to expect, and thus would not be able to enforce a specific behavior.

If a test exists in Tempest that would meet these criteria as a consequence of a change, the test must be removed according to the procedure discussed in this document. The API change should not be merged until all conditions required for test removal can be met.