Process ERB syntax in configuration file

lib/private_pub.rb

@@ -1,6 +1,7 @@
 require "digest/sha1"
 require "net/http"
 require "net/https"
+require 'erb'
 
 require "private_pub/faye_extension"
 require "private_pub/engine" if defined? Rails
@@ -18,7 +19,7 @@ def reset_config
 
     # Loads the  configuration from a given YAML file and environment (such as production)
     def load_config(filename, environment)
-      yaml = YAML.load_file(filename)[environment.to_s]
+      yaml = YAML.load(ERB.new(IO.read(filename)).result)[environment.to_s]
       raise ArgumentError, "The #{environment} environment does not exist in #{filename}" if yaml.nil?
       yaml.each { |k, v| config[k.to_sym] = v }
     end

spec/fixtures/private_pub.yml

@@ -6,3 +6,6 @@ production:
   server: http://example.com/faye
   secret_token: PRODUCTION_SECRET_TOKEN
   signature_expiration: 600
+staging:
+  server: <%= "http://" + "example.com" %>:<%= 9000 + 292 %>/faye
+  secret_token: "<%= %w{TEST SECRET TOKEN}.join('_') %>"

spec/private_pub_spec.rb

@@ -26,6 +26,12 @@
     PrivatePub.config[:signature_expiration].should eq(600)
   end
 
+  it "loads a simple configuration file via load_config and processing ERB template" do
+    PrivatePub.load_config("spec/fixtures/private_pub.yml", "staging")
+    PrivatePub.config[:server].should eq("http://example.com:9292/faye")
+    PrivatePub.config[:secret_token].should eq("TEST_SECRET_TOKEN")
+  end
+
   it "raises an exception if an invalid environment is passed to load_config" do
     lambda {
       PrivatePub.load_config("spec/fixtures/private_pub.yml", :test)