If you rspec stubs to test whether a class method, which accepts both positional and keyword arguments, is called with a positional argument, then RSpec::Mocks::Proxy will attempt to call the superclass's method. This will result in a confusing error (undefined method 'start' for Object:Class) if the Class in question does not inherit from another Class. This bug occurs under ruby-2.7, but not ruby-3.x. However, the bug does not occur if I remove **kwargs from the method definitions.
require 'rspec'
class Shell
def self.start(io,**kwargs)
end
end
class IO
def shell(**kwargs)
Shell.start(self,**kwargs)
end
end
describe IO do
subject { File.new(__FILE__) }
describe "#shell" do
it do
expect(Shell).to receive(:start).with(subject)
subject.shell
end
end
end
Rescuing NoMethodError in the test points us to RSpec::Mocks::Proxy line 228.
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-mocks-3.11.1/lib/rspec/mocks/proxy.rb:228:in `message_received'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-mocks-3.11.1/lib/rspec/mocks/proxy.rb:366:in `message_received'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-mocks-3.11.1/lib/rspec/mocks/method_double.rb:80:in `proxy_method_invoked'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-mocks-3.11.1/lib/rspec/mocks/method_double.rb:64:in `block (2 levels) in define_proxy_method'
/home/postmodern/test/ruby/rspec/spec/test_spec.rb:10:in `shell'
/home/postmodern/test/ruby/rspec/spec/test_spec.rb:22:in `block (3 levels) in <top (required)>'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example.rb:263:in `instance_exec'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example.rb:263:in `block in run'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example.rb:511:in `block in with_around_and_singleton_context_hooks'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example.rb:468:in `block in with_around_example_hooks'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/hooks.rb:486:in `block in run'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/hooks.rb:624:in `run_around_example_hooks_for'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/hooks.rb:486:in `run'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example.rb:468:in `with_around_example_hooks'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example.rb:511:in `with_around_and_singleton_context_hooks'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example.rb:259:in `run'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example_group.rb:646:in `block in run_examples'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example_group.rb:642:in `map'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example_group.rb:642:in `run_examples'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example_group.rb:607:in `run'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example_group.rb:608:in `block in run'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example_group.rb:608:in `map'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/example_group.rb:608:in `run'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/runner.rb:121:in `block (3 levels) in run_specs'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/runner.rb:121:in `map'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/runner.rb:121:in `block (2 levels) in run_specs'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/configuration.rb:2068:in `with_suite_hooks'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/runner.rb:116:in `block in run_specs'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/reporter.rb:74:in `report'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/runner.rb:115:in `run_specs'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/runner.rb:89:in `run'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/runner.rb:71:in `run'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/lib/rspec/core/runner.rb:45:in `invoke'
/home/postmodern/.gem/ruby/2.7.5/gems/rspec-core-3.11.0/exe/rspec:4:in `<top (required)>'
/home/postmodern/.gem/ruby/2.7.5/bin/rspec:23:in `load'
/home/postmodern/.gem/ruby/2.7.5/bin/rspec:23:in `<main>'
Expected behavior
IO
#shell
is expected to receive start(#<File:/home/postmodern/test/ruby/rspec/spec/test_spec.rb>) 1 time
Finished in 0.00547 seconds (files took 0.08959 seconds to load)
1 example, 0 failures
Actual behavior
IO
#shell
is expected to receive start(#<File:/home/postmodern/test/ruby/rspec/spec/test_spec.rb>) 1 time (FAILED - 1)
Failures:
1) IO#shell is expected to receive start(#<File:/home/postmodern/test/ruby/rspec/spec/test_spec.rb>) 1 time
Failure/Error: Shell.start(self,**kwargs)
NoMethodError:
undefined method `start' for Object:Class
# ./spec/test_spec.rb:10:in `shell'
# ./spec/test_spec.rb:21:in `block (3 levels) in <top (required)>'
Finished in 0.00563 seconds (files took 0.09395 seconds to load)
1 example, 1 failure
Failed examples:
rspec ./spec/test_spec.rb:18 # IO#shell is expected to receive start(#<File:/home/postmodern/test/ruby/rspec/spec/test_spec.rb>) 1 time
Subject of the issue
If you rspec stubs to test whether a class method, which accepts both positional and keyword arguments, is called with a positional argument, then
RSpec::Mocks::Proxy
will attempt to call the superclass's method. This will result in a confusing error (undefined method 'start' for Object:Class
) if the Class in question does not inherit from another Class. This bug occurs under ruby-2.7, but not ruby-3.x. However, the bug does not occur if I remove**kwargs
from the method definitions.Your environment
ruby 2.7.5p203 (2021-11-24 revision f69aeb8314) [x86_64-linux]
Steps to reproduce
Rescuing
NoMethodError
in the test points us toRSpec::Mocks::Proxy
line 228.Expected behavior
Actual behavior