Rails%203%20In%20Action

278 CHAPTER 10 Tracking state
10.5 Locking down states
This feature is going to take a little more than hiding the State select box on the form;
you also need to tell the application to ignore the state parameter if the user doesn’t
have permission to change the state. You implement this one piece at a time, beginning
with ensuring the State select box is hidden from those who should be unable to
change the state.
10.5.1 Hiding a select box
In previous chapters you’ve seen how you can hide links from certain users by using
the CanCan-provided can? view helper. You can also use this helper to hide the state
field in your comment form from users without the permission to change the state.
First, you write a Cucumber scenario to ensure that the State box is always hidden
from these users.
You add this particular scenario to the bottom of the features/creating
_comments.feature because its operation is based around creating a comment. The scenario
to ensure that you don’t see this state field is a short and simple one:
Scenario: A user without permission cannot change the state
When I follow "Change a ticket's state"
Then I should not see the "#comment_state_id" element
This scenario contains two simple steps: one to go to the ticket page and another to
assert that you don’t see the State select box. When you run this scenario by running
bundle exec features/creating_comments.feature:44, you see that the second step
isn’t yet defined:
Undefined step: "I should not see the "#comment_state_id" element"
As usual, the definition for this step appears at the bottom of Cucumber’s output:
Then /^I should not see the "([^"]*)" element$/ do |arg1|
pending # express the regexp above with the code you wish you had
end
To define this step, you put its definition inside of features/step_definitions/
application_steps.rb. To make it do the thing you want it to do, you can use one of
Capybara’s helper methods called find.
find can take many different forms, but in this case you’ll be using the following
form:
find(:css, css)
By passing these two options to find, Capybara will look for any element on the page
that matches the CSS selector. In this case, that would be css. If find does find an element
or even a collection of elements, it will only return the first element from this list.
If it can’t find anything, it will return nil. Using this knowledge, you can implement
this step now as shown, putting it inside features/step_definitions/application_steps.rb: