Progress indicator floods CI server build log with lots of distracting "Test run in progress..." messages

[stakx]

Description

VSTest's ProgressIndicator class doesn't play particularly well with some terminals, such as the one of AppVeyor for Linux. It repositions the cursor in order to display a varying number of dots behind a "Test run in progress" message, but that doesn't always work as intended. See e.g. this AppVeyor log or this slightly more realistic one, which gets needlessly long by these repetitive and malformatted messages and the actual test run output in-between can be hard to spot.

One can suppress it using the verbosity switch (e.g. dotnet test -v q) but that also suppresses other, useful messages (such as the list of skipped tests).

Would it be possible to adjust ProgressIndicator such that it plays along better with such terminals... or could you add a switch to disable specifically the progress indicator, while leaving other messages visible?

Steps to reproduce

I've prepared a small .NET Core test project (https://github.com/stakx/VSTestProgressIndicatorFloodRepro) that you can fork and add as a project on an AppVeyor account of your own, then trigger a build. The log you'll get should be very similar to the first one I posted above. (That project simply runs a few dummy tests that take long enough to give the progress indicator enough time to update itself a few times.)

[kaadhina]

We are tracking this using #2120