Monkey patch using capybara

I am using capybara minitest on windows using selenium driver … webkit
driver would require me to install QT so I am avoiding that

I am trying to simulate things like http error on an ajax request. I
have
this test in my feature as shown below.
I have a library that I include in my real controller, I then monkey
patch
that in my test to throw a 500 error. This seems to work,
but if I run “rake test:features” the tests all do not run because the
monkey patch effects the other tests it seems. I am not sure there is a
better approach ?
otherwise my tests have to be run individually somehow

the call: all(’.submit-btn’).first.click causes the controller
submit_req
action …

============================================

require “test_helper”

Capybara.default_max_wait_time = 18

require “main_controller_lib”

Monkey Patch here:

module MainControllerLib
def submit_req
puts “in submit stub”
render :text => “http error”, :status => 500
end
end

feature “Will handle ajax errors” do

scenario “ajax http error on main page”, js: true do
visit “/main/index”
all(’.submit-btn’).first.click

page.must_have_css(".fa-exclamation-circle")
el = page.find('.fa-exclamation-circle')[:tooltip]
assert_equal el, "Error on Submit:http error"

end
end