assert.EventuallyWithT: CollectT is not protected against concurrent use

[dolmen]

In assert.EventuallyWithT, if the tick is small, the calls to the condition may overlap (run simultaneously). However they share an access to an assert.CollectT instance which is not protected for concurrent use. Race condition may occur.

[dolmen]

Cc: @brackendawson

[dolmen]

I wonder if we should allow to run the condition function in parallel (and skip ticks) or if instead we should fix error collection to have separate instance for each call.

I have no idea how EventuallyWithT is used in the wild.

[dolmen]

There is already a pending MR that aims to fix this: #1395

[dolmen]

Duplicate of #1391.

[dolmen]

#1396 is also related, but not a duplicate.

[cszczepaniak]

#1438 proposes a solution to this that does not require adding any lock objects (i.e. assert.CollectT doesn't actually have to be threadsafe to solve this problem)

Edit: actually, it probably still does require a mutex. #1438 demonstrates the bug that occurs because of this issue, though.

[dolmen]

#1395 is a way to fix this.