`This is how I fixed the tests over an umbrella project problem:
mix test | tee test-logs.log
echo "=== Unit Test Summary ==="
grep "==>\| failure\|are no tests" test-logs.log
rm test-logs.log
This way the last thing in the log file on the build server is a summary of the above tests.
It may include some false positives if you are logging too much, but it does include what is needed.
Developer Rants 