$$testability: Unexpected behaviour of `findBindings` with `exactMatch === true`

[gkalpak]

$$testability.findBindings with opt_exactMatch set to true, uses a RegExp to match the specified expression against an element's bindings which results into unexpected (wrong?) behaviour.

The main problem is that is does not account for characters with special meaning in the context of a regular expression (e.g. $, | etc), which results in matching errors:

E.g. trying to match against the binding $index will produce the following RegExp:
/(^|\s)$index(\s|\||$)/ (which will always fail).

Or trying to match against any binding with a filter will yield unexpected matches (due to the | character).
E.g. trying to match against myValue | transformed will result into the following RegExp:
/(^|\s)myValue | transformed(\s|\||$)/(which would (among other things) erroneously match all bindings starting with myValue).

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Off the top of my head, either escaping expression or using string comparison with some additional checks (for leading/trailing characters) would solve this problem, but I am not sure what path we want to go down.
Alternatively, it should be documented somewhere (in protractor's docs?) that trying to do exact matching by binding has certain limitations.

[IgorMinar]

@juliemr can you take a look please?

[juliemr]

The $index case seems like a bug that we should fix - I'll make a PR which adds escaping. As for filters, I think this is working as intended and the documentation should just be updated.

[IgorMinar]

please send us the PR. thanks!

[gkalpak]

@juliemr I don't know why you say the filter case was working as expected (maybe I didn't make myself clear), but your fix solves the filter issue as well.

(Just to be clear, what I meant about filters was that the | in e.g. amount | currency has a special meaning in RegExp and (if not escaped) changes the meaning of the RegExp.)