The automated tests have the same sort of log format which is output to the console.
Most lines of test logs are of the form:
(status) | (test) | (description)
The test name or the description may be optional depending on the type of the test and where the line appears in the log.
Several status lines exist in the test:
reftest additional adds the word 'REFTEST' prepending the status column (e.g.):
REFTEST TEST-START |file:///home/cltbld/talos-slave/mozi...s/539167-1.svg
Also reftest just uses "TEST-PASS" instead of "INFO TEST-PASS" (likewise xpcshell tests).
There are several other lines that do not follow this convention
INFO Passed: 60569
INFO Failed: 44
INFO SimpleTest START
INFO SimpleTest FINISHED
INFO SimpleTest finished /tests/browser/base/content/test/test_offline_gzip.html in 312ms
INFO | runtests.py | Running tests: end
program finished with exit code 247