cabal test does not print executable output

There has been a new way for a few months, and tests results are even written to stdout on the file, not flushed at the end

cabal test --show-details=streaming

If you are using Cabal new-test (defualt on Cabal 3+):

$ cabal new-test --test-show-details=streaming

Older Cabal versions allow the output to be streamed using:

$ cabal test --show-details=streaming

--show-details=filter

Determines if the results of individual test cases are shown on the terminal. May be always (always show), never (never show), failures (show only failed results), or streaming (show all results in real time).

Read more in the Cabal User Guide.