Q:

specifying default format in routing spec

I have the following rspec routing spec but I need to specify :defaults => { :format => 'json' } in the post; how would I do this?
spec:
it "should route to all-locations-nav" do
  {:post => locations_nav_path }.should route_to(:controller => "api", :action => "locations_nav")
end

edit #1
so playing around, it looks like this fixes it:
it "should route to all-locations-nav" do
  {:post => locations_nav_path }.should route_to(:controller => "api", :action => "locations_nav", :format => "json")
end

but was curious if this is documented anywhere?

A:

Just set the format in the spec like this ...
it "routes to #create" do
  expect(:post => "/post").to route_to("posts#create", :format => :json)
end

Long explanation ...
The behavior you're seeing is not specific to :format, but is rather a relationship between the symbols you see in rake routes and the symbols that you pass to route_to.
For instance, given your example above, I'd expect something like the following when you run rake routes:
locations_nav   POST   /api/locations_nav(.:format)    api#locations_nav
The :controller and :action aren't explicitly flagged in the rake routes response, as those are built into Rails' MVC structure, but the :format is shown explicitly, and passing the :format to route_to taps into this. For example ...
Similarly, you'll probably see a few :id references in your rake routes output, which would be leveraged by passing an :id parameter to route_to.
Some additional examples around routing in RSpec can be seen in the "rspec-rails" documentation.
Internally, RSpec's route_to delegates to Rails' assert_recognizes, which you can see documented in the Rails documentation.

