Add option to provide current time when decoding JWT

[ZipFile]

• Makes possible to fake a time without using freezegun:freeze_time or unittest.mock:patch. Less monkey patching == better code.
• Makes possible to reuse current time fetched elsewhere (e.g. from request).

[codecov]

Codecov Report

Merging #267 (7a66496) into master (be8e914) will not change coverage.
The diff coverage is 100.00%.

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@@ Coverage Diff @@## master #267 +/- ##
=======================================
Coverage 92.94% 92.94% =======================================
Files 15 15 Lines 1418 1418 =======================================
Hits 1318 1318 Misses 100 100 

Impacted Files	Coverage Δ
jose/jwt.py	98.01% <100.00%> (ø)

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[blag]

Dependency injection to ease testing? 👍
Dependency injection to improve usability? 👍
Code churn for no discernible reason? 👎

If you have a good reason for prepending the now parameter like you did, I'll definitely consider it, but I haven't seen a good reason for it yet. Please point me to it if I missed it. 😅

[blag]

Why change the function signature? Wouldn't it be easier to append now=None to the end of the parameter list and keep the function signature the same? And then use

now=nowordatetime.utcnow()

to default to datetime.utcnow(), just in case anybody is using these private methods.

I realize that they're private methods, and people are signing up to keep their code up-to-date when they use these private methods, but there's no point in code churn without a good reason.

[ZipFile]

It was not part of the public API (this particular function does not even have docstring to serve as a documentation), so there was no hesitation to change the signature. Making now (required) positional argument better states the intention to me.

Either way, updated.

[jojolebarjos]

Hi folks, this feature would be very welcome, any chance this gets accepted?

[ZipFile]

Rebased with latest master, just in case.