Add Pusher.authenticate for authing on channels

This brings the API inline with `Pusher.trigger`, rather than having to
use the now deprecated `Pusher[name].authenticate(...)` style. The APIs
aren't quite 1-1 as `Pusher.authenticate` only takes a single channel
name, rather than 1-N channel names. That can come in a further PR.

Author: jackfranklin

README.md

@@ -178,15 +178,15 @@ It's possible to use the gem to authenticate subscription requests to private or
 ### Private channels
 
 ``` ruby
-Pusher['private-my_channel'].authenticate(params[:socket_id])
+Pusher.authenticate('private-my_channel', params[:socket_id])
 ```
 
 ### Presence channels
 
 These work in a very similar way, but require a unique identifier for the user being authenticated, and optionally some attributes that are provided to clients via presence events:
 
 ``` ruby
-Pusher['presence-my_channel'].authenticate(params[:socket_id], {
+Pusher.authenticate('presence-my_channel', params[:socket_id], {
   user_id: 'user_id',
   user_info: {} # optional
 })

lib/pusher/client.rb

@@ -235,6 +235,33 @@ def trigger_async(channels, event_name, data, params = {})
       post_async('/events', trigger_params(channels, event_name, data, params))
     end
 
+    # Generate the expected response for an authentication endpoint.
+    # See http://pusher.com/docs/authenticating_users for details.
+    #
+    # @example Private channels
+    #   render :json => Pusher.authenticate('private-my_channel', params[:socket_id])
+    #
+    # @example Presence channels
+    #   render :json => Pusher.authenticate('presence-my_channel', params[:socket_id], {
+    #     :user_id => current_user.id, # => required
+    #     :user_info => { # => optional - for example
+    #       :name => current_user.name,
+    #       :email => current_user.email
+    #     }
+    #   })
+    #
+    # @param socket_id [String]
+    # @param custom_data [Hash] used for example by private channels
+    #
+    # @return [Hash]
+    #
+    # @private Custom data is sent to server as JSON-encoded string
+    #
+    def authenticate(channel_name, socket_id, custom_data = nil)
+      channel_instance = channel(channel_name)
+      channel_instance.authenticate(socket_id, custom_data)
+    end
+
     # @private Construct a net/http http client
     def sync_http_client
       @client ||= begin

spec/client_spec.rb

@@ -128,6 +128,24 @@
         end
       end
 
+      describe '#authenticate' do
+        before :each do
+          @custom_data = {:uid => 123, :info => {:name => 'Foo'}}
+        end
+
+        it 'should return a hash with signature including custom data and data as json string' do
+          allow(MultiJson).to receive(:encode).with(@custom_data).and_return 'a json string'
+
+          response = @client.authenticate('test_channel', '1.1', @custom_data)
+
+          expect(response).to eq({
+            :auth => "12345678900000001:#{hmac(@client.secret, "1.1:test_channel:a json string")}",
+            :channel_data => 'a json string'
+          })
+        end
+
+      end
+
       describe '#trigger' do
         before :each do
           @api_path = %r{/apps/20/events}