Spawn sh on MacOS … doesn't

Running this code on a Mac:

const spawn = require('child_process').spawn;

spawn(
  '/bin/sh',
  ['-c', 'node -e "setInterval(() => console.log(`running`), 200)"'],
)

console.log(process.pid);

Then checking the process tree:

-+= 39818 remy node index.js
 \--- 39819 remy node -e setInterval(() => console.log(), 200)

This yeilds a single subprocess for the parent pid. This is unexpected because it should have first spawned sh then node, but it seems like MacOS skips this part (I'm still unsure how or why).

The same test on a non-Mac *nix system shows (notably from pid 18116):

$ ps  -o pid,ppid,cmd --forest
  PID  PPID CMD
17688 17687 -su
18116 17688  \_ node tests/fixtures/remy.js
18126 18116  |   \_ /bin/sh -c node -e "setInterval(() => console.log(`running`), 200)"
18128 18126  |       \_ node -e setInterval(() => console.log(), 200)
19771 17688  \_ ps -o pid,ppid,cmd --forest

Odd, but a gotcha for sure.