http: make globalAgent of http and https overridable

[shubheksha]

Previously globalAgent of http and https cannot be overriden by simply assigning a new value. This exposes those properties to allow overriding by assignment.

Fixes #9057

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

http

[mscdex]

/cc @jasnell Is there a faster method we could use to check for this instead of using instanceof? Like checking for a symbol or something?

[mscdex]

Actually, it would be best if we could avoid duplicating all of these options checks, since they're already being done in ClientRequest(). But it would still be nice to avoid instanceof in ClientRequest().

[shubheksha]

@mscdex, I didn't want to duplicate the options check too, but w/o the tests with options of type string fail as _defaultAgent cannot be added as a property on it. Instead of this, should I just check if type of options is Object or not? Is there another workaround?

[mscdex]

typeof options === 'object' && options !== null won't work since that would return true for url.URL instances as well.

[jasnell]

@mscdex ... you could export the context symbol from internal/url and check for that. All URL instances would have that set internally.

[mscdex]

+1 to the Symbol checking solution then

[Fishrock123]

I think this is a feature addition, so, tagging as semver-minor.

[gergelyke]

I guess this can be closed, seems to be fixed on master

[mscdex]

@gergelyke It's not fixed for https.request().

[BridgeAR]

This needs a rebase

[BridgeAR]

Ping @shubheksha do you want to follow up on this?

[BridgeAR]

Closing this due to the long inactivity.

@shubheksha I am sorry this could not land as is. Your work is much appreciated nevertheless! If you would like to pursue this further, please leave a comment or open a new PR.