Add cvar overtaken tests

[eileencodes]

While working on another project we noticed that there were no tests for
the cvar overtaken exception when using classes. This change adds a test
for cvar overtaken with classes and moves the cvar overtaken test for
modules into the new file.

Co-authored-by: Aaron Patterson tenderlove@ruby-lang.org

cc/ @tenderlove

[jeremyevans]

I think the new tests look good. However, I think this should go in test/ruby/test_variable.rb, as that is where the other class variable tests are. I think another reasonable alternative would be to split test/ruby/test_variable.rb into separate files per variable type, but that's significantly more work. I don't think we should add a new file named test/ruby/test_cvar.rb that only tests the overtaken behavior.

[simi]

🤔 https://github.com/ruby/spec/blob/master/language/class_variable_spec.rb could be also interesting point to add this kind of test.

[eileencodes]

I moved the new tests into test_variable.rb @jeremyevans 👍🏻

Edit: Actually they aren't passing in this file. Looking now.

[eileencodes]

Ok got the test fixed. Failing test is unrelated.

Failure: test_use_gemdeps(GemSingletonTest):
  Call trace does not match with given method type: #<struct RBS::Test::CallTrace method_name=:use_gemdeps, method_call=#<RBS::Test::ArgumentsReturn:0x00007f7b2bf30220 @arguments=["-"], @exit_value=nil, @exit_type=:return>, block_calls=[], block_given=false>.
  <["[Moduleuse_gemdeps] ReturnTypeError: expected `Array[Gem::Specification]` but returns `nil`"]> was expected to be empty.
/home/runner/work/ruby/ruby/src/gems/src/rbs/test/stdlib/test_helper.rb:263:in `assert_send_type'
test/stdlib/rubygems/Gem_test.rb:566:in `test_use_gemdeps'
     563:   def test_use_gemdeps
     564:     assert_send_type  "() -> nil",
     565:                       Gem, :use_gemdeps
  => 566:     assert_send_type  "(String) -> Array[Gem::Specification]",
     567:                       Gem, :use_gemdeps, "-"
     568:   end
     569: