The runner executed 422 files one process at a time, which is most of
the 12 to 40 minutes a CI lane spends in "Run tests". ECC_TEST_JOBS
above 1 now runs files through a pool of that many processes; output is
still buffered and printed per file, so logs read the same. The default
stays 1 and that path is the original synchronous spawnSync loop, so the
VM-driven runner test and the piped-output tests are unchanged.
ECC_TEST_ONLY is the mirror of ECC_TEST_SKIP: a comma-separated list of
path substrings, and only matching files run. CI uses it to give the
package-manager lanes just the suites that read the package-manager
variable instead of the whole suite.
Two real-process tests cover the pool (grouped output, counted failure,
summary last) and the ONLY filter.
Affaan Mustafa
9471ef4724