Couldn't parentGet be used here (to avoid double parsing) ?

Do we even need to parse this? We are just passing the string to watch, which parses this anyway. Yeah, I think I was confused about what's going oon in the two-way binding

I think we should parse it to init the child value. However, you can do this

scope.$watchCollection(parentGet, ...)

to not parse twice.

Unecessary inject() (here and below) ?

They are necessary. (many other tests have them). I think it's because the $rootScope etc. "globals" are set up in a module'S return fn.

Are the function names for the watch callbacks swapped?
Should't it be onParentValueChange here and onParentCollectionValueChange above?

OOC, what is the purpose of owOptref + owOptreference ?

Came from a c&p'd test, but owOptreference doesn't look like it's needed.

I expected it to remain {name: 'b'}. Interesting...

Aha, parsed expression with inputs and $$watchDelegates. Nice 😃

That's why it works? I'm actually confused by this right now.

Yes. Parsing {name: name} the resulting parsed expression has inputs, so it has a $$watchDelegate that will re-evaluate the expression whenever the inputs change value (in this case, inputs is the name property on $rootScope).
So, whenever $rootScope.name changes, the expression will be evaluated and will return a new object, thus the change will be propagated to the child.

So this works, but when you are going deeper, you need objectEquality watch - I've added that right now.