To avoid capturing build machine states into the snapshot

There were a few bugs in the original test that went unnoticed
because with the bug the test did not actually get run anymore.
This patch fixes the argument computation by accounting filtering
of the arguments, and uses spawnSyncAndExit{WithoutError} in
the test to enable better logging when the test fails.

We should use the node executable to run this test, instead of
counting on embedtest, the binary being tested, as the test runner.
Otherwise bugs can go unnoticed if the embedtest binary itself
does not work correctly.