Add specs for Fiber.blocking?

[HeroProtagonist]

relates to #823

Fiber.blocking? tells whether the current execution context is
blocking. [Feature #16786]

[HeroProtagonist]

@eregon 👋

I am a little confused by the failures.

spec/core/fiber/blocking_spec.rb

Lines 9 to 12 in 6a187f8

	fiber = Fiber.new { Fiber.current.blocking? }
	blocking = fiber.resume
	blocking.should == true

From the description of the feature. I would expect this to pass. However, it fails

A fiber created by Fiber.new(blocking: true) (the default Fiber.new) becomes a "blocking Fiber" and has no changes from current Fiber implementation

spec/core/fiber/blocking_spec.rb

Lines 32 to 35 in 6a187f8

	fiber = Fiber { Fiber.current.blocking? }
	blocking = fiber.resume
	blocking.should == false

Above causes NoMethodError. Has the fiber method been implemented?

We also introduce a new method which simplifes the creation of these non-blocking fibers:

[ioquatix]

Matz rejected Fiber method so I don't know where that spec came from. Can you tell me? Thanks!

[HeroProtagonist]

@ioquatix

🤦I made it to try and cover the different cases. I was only going off the description and did not read through the whole thread. Thanks for letting me know.

Now just need to figure out why the first case is not returning true

[ioquatix]

I believe we changed the default to be non-blocking by default. Originally we wanted to preserve the existing behaviour but it was deemed safe enough to allow non-blocking by default.

[HeroProtagonist]

Ah I see now https://docs.ruby-lang.org/en/master/Fiber.html#method-c-new.
Thanks for letting me know. Pushed the changes up. Hopefully all ✅ now.

[eregon]

Looks great, could you address my comments?

BTW, yes the CRuby bug tracker is not a great place to find out what was actually implemented unfortunately.

[HeroProtagonist]

I think I covered all the cases and hopefully got the wording right 🤞

[eregon]

This looks awesome, thank you!