RSpec: How do you implicitly filter tests based on the outcome of a previous test?

I'm iterating through a tree control on a webpage. Clicking on some nodes in the tree will change the content in FRAME_C, clicking on others will not. How do I filter a test to only run when the content has changed? Here's what I'm trying:

def viewDifferent? 
    if $prvView != $curView
        return true
    else
        return false
    end
end
...
describe "Exercising View" do

it "clicks a node in the tree control" do
    $prvView = $b.frame( :id, 'F开发者_C百科RAME_C').document.body.innertext

    Timeout.timeout(50) do
        spn.fire_event('onmouseup')
    end

    $curView = $b.frame( :id, 'FRAME_C').document.body.innertext
end

it "Runs only if the view is different", :if => viewDifferent? do
    puts "Doing some stuff."
end

end

My problem is that RSpec is evaluating the filter for all of my tests before executing any of them. In the above example viewDifferent? will always (and does) return false since the two global variables have yet to be set by the previous test.

Is there a way to do what I'm asking? I've been trying to figure this out for days.

A test should always run. It should setup the state it requires to execute the code path you expect. It seems to me that executing tests conditionally based on the outcome of other tests totally breaks the spirits of the tests.

You should already know the previous view and the current view are different, and if are not what you expect you have a failure.

Every test should have a very specific path through your code you expect it to execute, and you should fail if it doesn't. There isn't a way to do what you want because you shouldn't do it that way.

I'm not familiar w/ rspec, but have you tried using a Proc? For example...

it "Runs only if the view is different", :if => lambda { viewDifferent? } do
  puts "Doing some stuff."
end

A symbol as shorthand may even work...

it "Runs only if the view is different", :if => :viewDifferent? do
  puts "Doing some stuff."
end

As you currently have it, it's calling the viewDifferent? method as soon as the test is declared. What you really want is to pass a Proc so that it gets called when the test is run.