What I've found is that you now have to use the VSCode test command Test: Run All Tests but this is now much much slower as it seems to be launching each time for each test file. For my TDD with over 60 test files this is now a really painful experience. Hopefully this is just a bug and the intended DX is still quick and responsive.
old Dart: Run All Tests -> 2-3sec
new Test: Run All Tests -> 40-60sec
Originally posted by @lloydrichards in #3594 (comment)