fix: Redis#exists(key) returns Integer as the default behaviour

[AkkyOrz]

Description

redis-rb/lib/redis.rb

Lines 576 to 596 in c97360b

	# Determine how many of the keys exists.
	#
	# @param [String, Array<String>] keys
	# @return [Integer]
	def exists(*keys)
	if !Redis.exists_returns_integer && keys.size == 1
	if Redis.exists_returns_integer.nil?
	message = "`Redis#exists(key)` will return an Integer in redis-rb 4.3. `exists?` returns a boolean, you " \
	"should use it instead. To opt-in to the new behavior now you can set Redis.exists_returns_integer = " \
	"true. To disable this message and keep the current (boolean) behaviour of 'exists' you can set " \
	"`Redis.exists_returns_integer = false`, but this option will be removed in 5.0. " \
	"(#{::Kernel.caller(1, 1).first})\n"
	::Kernel.warn(message)
	end
	exists?(*keys)
	else
	_exists(*keys)
	end
	end

Redis#exists(key) will return an Integer in redis-rb 4.3. exists? returns a boolean, you " \
"should use it instead. To opt-in to the new behavior now you can set Redis.exists_returns_integer = " \
"true. To disable this message and keep the current (boolean) behaviour of 'exists' you can set " \
"Redis.exists_returns_integer = false, but this option will be removed in 5.0.

After reading the error message, I interpreted it as follows. (The text in parentheses is my own completion)

• version 4.3 or later, Redis#exists(key) is supposed to return integer.
• Use Redis#exists?(key) instead (if you want to return a boolean in version 4.3 or later).
• Set Redis.exists_returns_integer = true if you want to use the "new" behaviour (for users of version 4.3 or earlier)

However, in my environment using redis-rb 4.4, when Redis.exists_returns_integer = nil (default setting), Redis#exists(key) returns boolean with the above error message. I suspect that this is a bug.

When this message was added, the version was prior to 4.3 (4.2.1).
So it would have returned the previous behavior (boolean) when Redis.exists_returns_integer = nil or Redis.exists_returns_integer = false.
However, now (or later) it returns the previous behavior (boolean) only when Redis.exists_returns_integer = false, and not when
I think it should return integer if Redis.exists_returns_integer = nil (default) or Redis.exists_returns_integer = true.

Perhaps Redis.exists_returns_boolean will be more suitable and simpler for opt-in/opt-out applications.

Actually, this is my first pull request, so I may have the wrong way to contribute!
Please let me know if I'm wrong.
Thank you!:blush:

[byroot]

However, in my environment using redis-rb 4.4, when Redis.exists_returns_integer = nil (default setting), Redis#exists(key) returns boolean with the above error message. I suspect that this is a bug.

Yes, the bug is that I forgot to change the default when I released 4.3 🤦

[byroot]

Fixed in cf7e628, thank you nonetheless for your PR.