Use GOOGLE_MAP_API_KEY when loading JS source

Google Maps recently changed their billing model which resulted in an API key always being required when using the Javascript API.

If you want to see the map in development mode then set GOOGLE_MAP_API_KEY in $APP_ROOT/.env.local or change the one in $APP_ROOT/.env.development.

.env.development

@@ -0,0 +1 @@
+GOOGLE_MAP_API_KEY=fake-google-map-api-key

app/helpers/google_maps_api_helper.rb

@@ -0,0 +1,7 @@
+module GoogleMapsApiHelper
+  def google_maps_api_source_url
+    api_key = ENV.fetch('GOOGLE_MAP_API_KEY')
+
+    "https://maps.googleapis.com/maps/api/js?key=#{api_key}&region=GB&libraries=geometry"
+  end
+end

app/views/locators/index.html.erb

@@ -6,5 +6,5 @@
 
 
 <% content_for :body_end do %>
-  <script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?region=GB&libraries=geometry"></script>
+  <%= javascript_include_tag google_maps_api_source_url %>
 <% end %>

spec/helpers/google_maps_api_helper_spec.rb

@@ -0,0 +1,11 @@
+require 'rails_helper'
+
+RSpec.describe GoogleMapsApiHelper, '#google_maps_api_source_url' do
+  it 'returns a URL which includes the API key' do
+    allow(ENV).to receive(:fetch).with('GOOGLE_MAP_API_KEY').and_return('fake-key')
+
+    expect(google_maps_api_source_url).to eq(
+      'https://maps.googleapis.com/maps/api/js?key=fake-key&region=GB&libraries=geometry'
+    )
+  end
+end