lerna ls --since REF --json returns empty string with no changed packages instead of empty array

[bdwain]

Expected Behavior

lerna ls --since REF --json prints [] if there are no changed packages

Current Behavior

lerna ls --since REF --json prints an empty string if there are no changed packages

Possible Solution

not sure off the top of my head but i'd be happy to do a pr to fix it

Steps to Reproduce (for bugs)

on master, run lerna ls --since master --json

Context

i have a script that runs this to get changed packages. It needs a special case to handle no packages which is unnecessary

the behavior seems to have changed recently. it used to return a non-zero exit code if there were no unchanged packages, which also seemed wrong.

Your Environment

Executable	Version
lerna --version	3.13.0
yarn --version	1.12.3
node --version	10.14.2

OS	Version
NAME	VERSION

[evocateur]

lerna ls has never exited non-zero with no results. lerna changed does exit non-zero, as it was intended to be a filter for lerna publish in CI (for example). (lerna changed is equivalent to lerna ls --since)

ba54439 was a bit overzealously trying to avoid an empty console.log(). Perhaps testing result.text.length instead of result.count is more appropriate? It would still emit an empty array, in your case.

I have a fix forthcoming.

[evocateur]

As for the non-zero exit with no results, that's a breaking change. I largely agree with it, btw, as it matches the behavior of grep with no results.

[bdwain]

thanks!