Add support for test phases

[psss]

As discussed on the stakeholder meeting, there are use cases related to tracking individual results of test "phases". These can be created using one of the following ways:

• defining a beakerlib phase using rlPhaseStart and rlPhaseEnd
• explicitly calling rstrnt-report-result to submit a subresult

When run in Beaker, the rlPhaseEnd command called during a beakerlib test execution actually calls rlReport which uses BEAKERLIB_COMMAND_REPORT_RESULT command to report the result and, if I'm not mistaken, this defaults to using rstrnt-report-result. @sopos, please correct me if I'm wrong.

The effect is that each beakerlib phase and rstrnt-report-result call create a "subresult" which is shown in the Beaker web interface under the actual test. The proposal is to add a similar support for subresults to tmt.

Here are some more ideas caught from the brainstorm:

• We could inject a custom script using BEAKERLIB_COMMAND_REPORT_RESULT and perform necessary actions on the guest
• The result specification could be extended to include a list of subresults (which would be similar to the check attribute)
• It would be good to report detected avc failures for each test phase separately
• Report plugins would have to invent the proper mapping to e.g. junit format as the spec does not know subresults

All in all it seems this would bring a substantial level of complexity (currently the test granularity was simply defined by the test metadata definition for each test) so we should discuss this well before jumping into the implementation.

Base Work

• spec — https://github.com/teemtee/tmt/pull/2933
• class — https://github.com/teemtee/tmt/pull/3094
• https://github.com/teemtee/tmt/pull/3106
• actual saving of subresults into results.yaml - https://github.com/teemtee/tmt/pull/3200

Report Plugins

• display — https://github.com/teemtee/tmt/pull/3107
• html — https://github.com/teemtee/tmt/pull/3095
• junit
  • https://github.com/teemtee/tmt/pull/3150
  • https://github.com/teemtee/tmt/pull/3177
• polarion — https://github.com/teemtee/tmt/pull/3166