• Using junior people for testing may be reasonable If you build simple, low risk commodity products. If you only have junior developers writing and maintaining test code for complex systems, you’re not saving as much as you think.

• If you don’t have solid testing harnesses with good CI testing, you’re wasting time

• repeatable testing is important - friends don’t let friends ship regressions

Testing Challenges in Realtime(ish) systems

Unfortunately, some things are very hard to test properly. This is especially true of reactive, real-time systems. Subtle changes of sequence and timing in external activity/inputs can change the execution path.
Reactions which produce external outputs can cause feedback and ripple effects in a real world deployment which simplistic testing might never trigger.

Limits of Unit Tests

There are always some things you can still test with traditional unit testing.
Where it can be used, it should be.

Sequencing Sensitivity

Theoretically, a purely stateless system would be immune to sequencing related problems. However that’s only theory, and most complex real-time systems are anything but stateless (try implementing a stateless state-machine…).