Render_template expectation - surprising pattern matching issue

Hey guys,

we just found out by accident that rspec seems to apply a pretty
confusing mechanism to ensure that a certain template is rendered.

To clarify, consider this standard controller spec:

working

it ‘GET edit’ do
get :edit, :id => ‘37’
response.should render_template(:edit)
end

So far, so good. Now to the surprising part:

NOT working

it ‘GET edit’ do
get :edit, :id => ‘37’
response.should render_template(:eda)
end

-> here’s the surprise: working

it ‘GET edit’ do
get :edit, :id => ‘37’
response.should render_template(:edi)
end

Apparently rspec uses a pretty generous pattern matching to ensure
that a certain template is rendered.

If I had to guess, I’d say that’s because rspec wants to ignore path /
namespacing / different file endings (html.haml, html.erb and so on).

I still think this approach is suboptimal for two reasons:

1.) It violates the principle of least suprise, this behaviour is more
like “the biggest surprise possible” - who would have thought that
example nr.3 is working?

2.) I can easily imagine a situation where 2 or more actions start
with the same letters. In this case, what would happen if you changed
the “render_template”-call (i.e. shortening the template name) and
remove one action.
Wouldnt the specs still be green although one view would be completely
missing?

2 questions:

1.) Is this a bug or a feature?

2.) Why not change the pattern matching that it still ignores paths
and file endings, but at least tries to match the expected template
exactly to the rendered template?

On 2010-07-26 11:12 AM, Timo Rößner wrote:

 response.should render_template(:edit)

-> here’s the surprise: working

Wouldnt the specs still be green although one view would be completely
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I’ve experienced a bit of pain with making sure the right view gets
rendered. Initially, I was doing essentially what you are doing, but
noticed that the specs would pass even if I didn’t render the view (ie,
the view wasn’t there). Then I discovered integrate_views, which helped
immensely in that regard, until I later discovered that I had to mock
and stub everything that the view expected. Hated that. I’ve since
started using something that is not quite as unobtrusive as I’d like,
but I much prefer the results. I don’t integrate_views any more and I
set an expectation on the controller to render. Something like:

describe ‘get :index’ do
it ‘should render the index view’ do
controller.should_receive(:render).with(:index)
get :index
end
end

The unfortunate part of this is that I must then explicitly render the
view in the controller action:

def index

render :index
end

I wish I didn’t have to do it that way, but so far, this is the best I
can do to balance specing the controller with keeping things isolated. I
openly admit there might be a better solution and I may very well have
overlooked something obvious. I didn’t spend a lot of time trying to get
this figured out correctly, so there may be a better way.

Peace,
Phillip

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