Rspec view test with url parameters

I have a page dashboard.html.erb that may be redirected to from several different controllers/actions. When it receives the redirect, it also receives several url parameters.

Controller code:

class PlansController
  def some_action
    redirect_to dashboard_path(show: "default", cool_array: ["test", "test"])
  end
end

class StaticpagesController
  def dashboard
  end
end

View code:

<% if cool_array %>
  <% cool_array.each do |a| %>
    <li><%= a %></li>
  <% end %>
<% end %>

<script>
var show = getParamFromURL("show")
// some sort of function that returns the value of the show param, in this case, "default"
if (show == "default") {
  $("#default").addClass("show");
} else {
  $("#other").addClass("hidden");
}
</script>  

Because these are redirects, controller testing with render_views will not work. Therefore, I had thought to construct my tests so that the controller spec tests that the right parameters are being passed, and the view spec tests that if certain parameters are present, the right css classes are present, or whatever. But in my view spec, I'm having trouble simulating the passing of parameters.

This seems to be the only other question out on this that I found: RSpec View testing: How to modify params?

But none of the solutions have worked for me; I'm not sure in this case I need a helper... which seems a bit contrived...

I have tried (from the linked SO question above):

before do
  controller.request.path_parameters[:cool_array] = ["test","test"]
end
# => ActionView::Template::Error:
#  undefined local variable or method `cool_array' for #<#<Class:0x007fe2d9815100>:0x007fe2d90a62e8>
# thrown by line in view file with <% if cool_array %>

before do
  view.stub(:params).and_return({cool_array: ["test", "test"]})
end
# => ActionView::Template::Error:
#  undefined local variable or method `cool_array' for #<#<Class:0x007fe2d9815100>:0x007fe2d90a62e8>
# thrown by line in view file with <% if cool_array %>

helper.params = {:cool_array => ["test", "test"]]}
# honestly not even sure this is right, because it can only go into a describe block (not a before, not an it) and then it throws:
# NoMethodError:
#   undefined method `params=' for #<#<Class:0x007fd7cc8f4930>:0x007fd7cc8a5060>

And they all fail with: