ruby - Unable to activate rspec-2.12.0, because rspec-core-2.13.1 conflicts with rspec-core (~> 2.12.0)

Question

When I try to do rspec rspec_001.rb I get the above error

How can I get around the error and run tests?

contents of rspec_001.rb:

require 'rspec'

class Dummy < Object
end

describe "a test" do
end

I can't seem to use bundle exec rspec rspec_001.rb as this is not a Rails project with a Gemfile.

Answer 1

gem update rspec fixed this and now the spec runs ("No examples found." is ok, there aren't any) -

rspec rspec_001.rb
No examples found.

Finished in 0.00011 seconds
0 examples, 0 failures