Add Verify Property harness

[leobalter]

signature:

verifyProperty(
  Object obj,
  String|Symbol name,
  Object|undefined {
    Boolean writable,
    Boolean configurable,
    Boolean enumerable
  },
  Object { Boolean restore }
);

You can set an expliecit restore option if you need to reuse the same property, works well for accessor descriptors too.

I've had to add a monkey patch to $ERROR in tests asserting negative effects, it is ugly, but it works.

cc @littledan;

[leobalter]

this undefined value got me into a lot of trouble while writing the tests.

[littledan]

Seems good to me. I could imagine more features, like value in the options. I also don't know the whole motivation for this approach as opposed to adding restore versions of the individual test functions. But this should be useful for my test.

[leobalter]

Seems good to me. I could imagine more features, like value in the options.

this is for sure one of the goals. I had this in mind when I created this function and I'm planning to follow - in another PR - with support to verify values for data and accessor descriptors.

I also don't know the whole motivation for this approach as opposed to adding restore versions of the individual test functions. But this should be useful for my test.

This solves a lot of other problems we've had with the other individual problems. The calling order for each function was one of the most annoying.