work around the fact that timeout is different on my Mac than on Travis

test/adapters/rack_test.rb

@@ -17,8 +17,16 @@ module Adapters
     # not using shared test because error is swallowed by Sinatra
     def test_timeout
       conn = create_connection(:request => {:timeout => 1, :open_timeout => 1})
-      err = assert_raise(Faraday::Error::ClientError) { conn.get '/slow' }
-      assert_include err.response[:body], 'execution expired'
+      err = assert_raise { conn.get '/slow' }
+
+      case err
+      when Faraday::Error::ClientError
+        # happens on Mac OS
+        assert_include err.response[:body], 'execution expired'
+      else
+        # happens on Travis
+        assert_instance_of Timeout::Error, err
+      end
     end
 
   end