flutter test has a --start-paused flag that can be passed to pause the test on start and output a vm service URI for the test. This is useful for debugging a test with DevTools for example.

Sometimes there is also a need to pause the test on exit to inspect the end state (one example is to inspect the memory of the test isolate to track down leaks). There is a service extension to pause the test isolate after tests: ext.test.pauseAfterTests, but currently no flutter test flag to set its value. Some internal tools call this service extension after connecting to the test isolate's vm service, but it would be nice if this could also be accessed from CLI.

@christopherfujino