Raise bing errors for statuses 403, 500, 503

Bing returns the status codes within the json response. When a request is
forbidden, it will return a 403. If there is an internal server error,
it will return a 500. And if the service is unavailable for some other
reason, it will return a 503. That information was obtained from bing's
[Status Codes and Error
Handling](https://msdn.microsoft.com/en-us/library/ff701703.aspx)
documentation.

We handle those three status codes here to raise
`Geocoder::RequestDenied` (for 403) and `Geocoder::ServiceUnavailable`
(for 500 and 503). This allows for the users of the Geocoder to handle
those errors in their applications.

lib/geocoder/lookups/bing.rb

@@ -44,6 +44,11 @@ module Geocoder::Lookup
         return doc['resourceSets'].first['estimatedTotal'] > 0 ? doc['resourceSets'].first['resources'] : []
       elsif doc['statusCode'] == 401 and doc["authenticationResultCode"] == "InvalidCredentials"
         raise_error(Geocoder::InvalidApiKey) || Geocoder.log(:warn, "Invalid Bing API key.")
+      elsif doc['statusCode'] == 403
+        raise_error(Geocoder::RequestDenied) || Geocoder.log(:warn, "Bing Geocoding API error: Forbidden Request")
+      elsif [500, 503].include?(doc['statusCode'])
+        raise_error(Geocoder::ServiceUnavailable) ||
+          Geocoder.log(:warn, "Bing Geocoding API error: Service Unavailable")
       else
         Geocoder.log(:warn, "Bing Geocoding API error: #{doc['statusCode']} (#{doc['statusDescription']}).")
       end

test/fixtures/bing_forbidden_request

+{
+   "authenticationResultCode":"ValidCredentials",
+   "brandLogoUri":"http:\/\/dev.virtualearth.net\/Branding\/logo_powered_by.png",
+   "copyright":"Copyright © 2011 Microsoft and its suppliers. All rights reserved. This API cannot be accessed and the content and any results may not be used, reproduced or transmitted in any manner without express written permission from Microsoft Corporation.",
+   "resourceSets":[
+      {
+         "estimatedTotal":0,
+         "resources":[
+
+         ]
+      }
+   ],
+   "statusCode":403,
+   "statusDescription":"OK",
+   "traceId":"907b76a307bc49129a489de3d4c992ea|CH1M001463|02.00.82.2800|CH1MSNVM001383, CH1MSNVM001358, CH1MSNVM001397"
+}

test/fixtures/bing_internal_server_error

+{
+   "authenticationResultCode":"ValidCredentials",
+   "brandLogoUri":"http:\/\/dev.virtualearth.net\/Branding\/logo_powered_by.png",
+   "copyright":"Copyright © 2011 Microsoft and its suppliers. All rights reserved. This API cannot be accessed and the content and any results may not be used, reproduced or transmitted in any manner without express written permission from Microsoft Corporation.",
+   "resourceSets":[
+      {
+         "estimatedTotal":0,
+         "resources":[
+
+         ]
+      }
+   ],
+   "statusCode":500,
+   "statusDescription":"OK",
+   "traceId":"907b76a307bc49129a489de3d4c992ea|CH1M001463|02.00.82.2800|CH1MSNVM001383, CH1MSNVM001358, CH1MSNVM001397"
+}

test/unit/lookups/bing_test.rb

@@ -82,4 +82,18 @@ class BingTest < GeocoderTestCase
       l.send(:results, Geocoder::Query.new("service unavailable"))
     end
   end
+
+  def test_raises_exception_when_bing_returns_forbidden_request
+    Geocoder.configure(:always_raise => [Geocoder::RequestDenied])
+    assert_raises Geocoder::RequestDenied do
+      Geocoder.search("forbidden request")
+    end
+  end
+
+  def test_raises_exception_when_bing_returns_internal_server_error
+    Geocoder.configure(:always_raise => [Geocoder::ServiceUnavailable])
+    assert_raises Geocoder::ServiceUnavailable do
+      Geocoder.search("internal server error")
+    end
+  end
 end