Using stub_const to hijack a constant

example_spec.rb

# Lines marked with pry are just for testing in a rails console

require 'rspec/mocks' # pry
include RSpec::Mocks::ExampleMethods # pry

# This bypasses the warning that the method isn't called inside of a test
RSpec::Mocks.with_temporary_scope do # pry
  stub_const(
    'MyClass',
    instance_double(
      'MyClass',
      class_method: :foo,
      new: instance_double(
        'MyClass',
        instance_method: 7
      )
    )
  ) 
  puts MyClass.class_method # pry
  puts MyClass.new.instance_method # pry
end # pry