adds spec for an empty keyword splat to a method that does not accept…

[moofkit]

… keywords

Closing #745

Passing an empty keyword splat to a method that does not accept keywords
no longer passes an empty hash, unless the empty hash is necessary for
a required parameter, in which case a warning will be emitted. Remove
the double splat to continue passing a positional hash. Feature #14183

h = {}; def foo(*a) a end; foo(**h) # []
h = {}; def foo(a) a end; foo(**h)  # {} and warning
h = {}; def foo(*a) a end; foo(h)   # [{}]
h = {}; def foo(a) a end; foo(h)    # {}

[andrykonchin]

Looks good but there is no test for this case:

h = {}; def foo(*a) a end; foo(**h) # []

[andrykonchin]

Checking for not raising exception is excessive to it's a common practice in RubySpec not to use it at all. If exception is raised a test will fail anyway.

[andrykonchin]

Also we can test the warning itself in this case

h = {}; def foo(a) a end; foo(**h)  # {} and warning

[moofkit]

@andrykonchin Thanks for review!

Looks good but there is no test for this case:

h = {}; def foo(*a) a end; foo(**h) # []

Yeah, I was started the spec because of comment, that behavior was changed. But when I checked with ruby 2.7 the result was same to 2.6. I think may be there was some mistake... Now I checks this one more time and it's really was changed 😅

Thanks for point this!

[andrykonchin]

Great 👍