Fix deep equal comparison between promises

[NoxWings]

Fix issue #216 by explicitly checking Promise instances

Background

I found that sinon spy calledWith does not properly check promises equality and always returns true.
Reported here

Solution

Simple fix, I've just added explicit Promise instance checking similar to how Error or RegExp are checked. I've also added a couple tests to verify it. I haven't added a test to check promises against other type of data as that was already working but I can add a explicit test for that case if you want.

How to verify

1. Check out this branch
2. npm t (or just check the ci)

[codecov]

Codecov Report

Merging #217 (f839c29) into master (ca676e4) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #217   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           27        27           
  Lines          512       514    +2     
=========================================
+ Hits           512       514    +2     

Flag	Coverage Δ
unit	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
lib/deep-equal.js	100.00% <100.00%> (ø)

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[mantoni]

Thanks a lot! 👍

We're still supporting old browsers like IE 11, where the Promise object doesn't exist. To avoid a ReferenceError, an additional typeof check is needed before using Promise. The corresponding test cases should be skipped in environments that don't support promises.

Here is an example how we do this for symbols:

samsam/lib/deep-equal.test.js

Lines 376 to 382 in ca676e4

	before(function () {
	if (typeof Symbol === "function") {
	symbol = Symbol("id");
	} else {
	this.skip();
	}
	});

[NoxWings]

Hi again sorry for the delay!
should I add any checks on the code itself apart from the tests?

[mantoni]

@NoxWings Yes, it needs a typeof Promise check in the code as well. Thank you 🙏

[fatso83]

ping :) sinonjs/sinon#2345

[fatso83]

Actually, from Sinon 10 on (released on March 22) we do not support IE 11, so I see no reason to have this blocking. Merging :)