Remove void return type for propertyDiff()

[rak3n]

for issue #186

• Add undefined check on onePropertyDiff return value, so as to return empty array from propertyDiff.

[maritz]

Thank you for this PR! ❤️

Could you add a test to make sure this stays working as intended after this PR? Something in typescript.test.ts that just makes sure void isn't the return type or value.

Do you think this would require a major version bump according to semver?

[rak3n]

Hey @maritz,
many thanks for reviewing, have added test and dropped void from return type.
This will modify the way propertyDiff is used in older code to handle no differences in property for a key, so I think it will be a major bump.

[maritz]

Hmmm, I think this test would not have failed previously, right? The only real change is the return type of an item inside the array. So you'd have to make a test that loops over the diff and explicitly tries to access an item in it.

Something like

diffBeforeUpdate.forEach((diffItem) => { 
  // should never be called, but also shouldn't cause a TS error
  console.log('diff had item', diffItem);
  t.fail('should never reach this');
});

[rak3n]

interesting, the resultant from the earlier version was returning [undefined] (as the JS func which doesn't return anything is undefined for return), and hence this test would have failed for deepEquals when compared with [] on the previous version. Happy to make change if that's not the case here

[maritz]

This will modify the way propertyDiff is used in older code to handle no differences in property for a key, so I think it will be a major bump.

Yeah, I was thinking so as well. I'm kind of hesitant to just publish a v3 only for this rather minimal change. But on the other hand I can't really promise when other bigger changes are coming.

I guess I'll add this and some dependency updates into a v3 soon and not hold it up for other stuff.