Samuel Mullen What could possibly go wrong?

Testing Geocoder with RSpec and Cucumber

by Samuel Mullen

Posted on Feb 3, 2012


If you are using the Geocoder gem then your tests related to geocoding are most likely hitting one of the gem’s geolocation providers. That’s probably not what you want: 1) your tests run slower; 2) you use up your request quota for your specified provider; 3) and most importantly, you are not able to control the data returned. A good solution to this is to use the fakeweb gem - and it’s really easy to set it up.

The Steps

First, add fakeweb to your Gemfile under the :test group and then “bundle install”.

group :test do
  ...
  gem 'fakeweb'
  ...
end

Now, put the following code in a file under spec/support (or test/support). I use geocoding.rb, but you can name it anything you wish.

google_json = <<-JSON
{
  "status": "OK",
  "results": [ {
    "types": [ "street_address" ],
    "formatted_address": "45 Main Street, Long Road, Neverland, England",
    "address_components": [ {
      "long_name": "45 Main Street, Long Road",
      "short_name": "45 Main Street, Long Road",
      "types": [ "route" ]
    }, {
      "long_name": "Neverland",
      "short_name": "Neverland",
      "types": [ "city", "political" ]
    }, {
      "long_name": "England",
      "short_name": "UK",
      "types": [ "country", "political" ]
    } ],
    "geometry": {
      "location": {
        "lat": 0.0,
        "lng": 0.0
      }
    }
  } ]
}
JSON

FakeWeb.register_uri(:any, %r|http://maps\.googleapis\.com/maps/api/geocode|, :body => google_json)

To reference the above file in Cucumber, add the following line to your features/support/env.rb file:

require Rails.root.join("spec/support/geocoding")

The Explanation

Even though there is a lot of text in the geocoding.rb file, there really isn’t much going on. In the “here document” (the parts between google_json = <<-JSON and JSON) a big blob of JSON data gets assigned to the google_json variable. That’s it.

On the last line, we tell the FakeWeb gem that any call to Google’s API needs to be captured and then return a blob of JSON data (what’s stored in the google_json variable) “successfully”. Note that the URL used above is a regular expression and is only a portion of the full address in order to capture everything sent to that location.

It is entirely likely that you are using an alternate provider to Google. If this is the case, you will need to retrieve the appropriate JSON data yourself. You can find this data in the Geocoder test fixtures. Look for the files beginning with your provider and ending with “madison_square_garden.json”.

Alternate URLs for providers can be found in the Geocoder “lookups” files. The URLs reside in the query_url method.

If you’ve done everything correctly, your test should now stay local to your machine and return only the data you’ve specified. From here, you can set up tests for failures, alternate geolocation providers, specific latitude/longitude coordinates, and more. You now have all that is necessary to test geolocation calls.

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About me


I live in the greater Kansas City area with my beautiful wife, our two great kids, and our dog. I've been programming using Open Source technologies since '97 and I'm currently an independent software developer specializing in Ruby on Rails and iOS. I am for hire.

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