I recently adopted Swift Testing in FlyingFox for all unit tests and was really impressed with the performance:
Swift Testing
✔ Test run with 354 tests passed after 1.359 seconds.
XCTest
Executed 352 tests, with 0 failures (0 unexpected) in 7.796 (7.815) seconds
These results are from running on GitHub Actions.
Thank you to the team for such a fundamental change — can't wait to see where the future goes from here.
I'm guessing you weren't parallelising your tests with XCTest? That would explain the huge speed up but I'd love to be proven wrong!
I wasn't but are you able to parallelise with % swift test ?
With xcodebuild parallelisation its marginally faster (5.8s) but it is also difficult to get an elapsed time output;
% xcodebuild -scheme FlyingFox-Package -destination 'platform=macOS' -parallel-testing-enabled YES test-without-building
...
xcodebuild[4830:5223951] [MT] IDETestOperationsObserverDebug: 5.868 elapsed -- Testing started completed.
To parallelize XCTest using Swift Package Manager, simply pass the --parallel option. Note that XCTest parallelizes by spawning multiple processes while Swift Testing uses Swift concurrency, so the pros and cons are different.
using % swift test --parallel the XCTests are around 3s
Hey, that's still more than 2x as fast. I'll take that win. 
No Objective-C for the win 
That too!