Fix an incorrect outcome (corner cases)

[pawelpasterz]

Fixes #914

Due to the incorrectly implemented logic regarding the status update, there were cases when flaky tests obscure failed results.
The following must occur:

1. The matrix needs to have both flaky and failed tests (at least one of each)
2. TestExecutions need to be returned in a specific order:
   1. Failed execution must be consumed by flank before flaky one
   2. The following flaky execution must be actually failed but the outcome of all re-runs is success
3. Then flank does what is the following:
   1. The outcome is set to failure when failed test/shards/executions are processed

   private fun Outcome?.updateOutcome(
      when {
          ...
          else -> this?.summary  // at this point SavedMatrix.outcome == success, flank changes it to failure
          ...
   })

   2. When flank reaches case where step summary is failure but execution is success it sets SavedMatrix outcome to flaky

   updateOutcome(flakyOutcome = it.step.outcome?.summary != this?.summary) // flakyOutcome == true 

   3. Due to incorrect order in when condition failure check is never reached

   private fun Outcome?.updateOutcome(
          flakyOutcome: Boolean
      ) {
          outcome = when {
              flakyOutcome -> flaky 
              // flank should escape here with failure status persisted, but since flakyOutcome == true SavedMatrix.outcome is changed to flaky
              outcome == failure || outcome == inconclusive -> return 
              outcome == flaky -> this?.summary?.takeIf { it == failure || it == inconclusive }
              else -> this?.summary
          } ?: outcome
      }

Proposed fix

1. Change order in when condition to always check for failure first

   private fun Outcome?.updateOutcome(
          flakyOutcome: Boolean
      ) {
          outcome = when {
              outcome == failure || outcome == inconclusive -> return // escape when failure/inconclusive outcome is set
              flakyOutcome -> flaky 
              outcome == flaky -> this?.summary?.takeIf { it == failure || it == inconclusive }
              else -> this?.summary
          } ?: outcome
      }

2. Add unit tests to cover this case.

Test Plan

How do we know the code works?

All tests pass and build finish successfully.
No easy way to verify it without previously prepared data/results

Checklist

• Documented
• Unit tested
• release_notes.md updated

[jan-goral]

Suggested change

	fun `savedMatrix should have failed outcome when at least one test is failed and the last one is flaky`() {
	fun `savedMatrix should have failed outcome when at least one test is failed`() {