Fixes invalid args issue (#92)

Author: rashidsp

lib/optimizely.rb

@@ -261,6 +261,16 @@ def is_feature_enabled(feature_flag_key, user_id, attributes = nil)
         return false
       end
 
+      unless feature_flag_key
+        @logger.log(Logger::ERROR, 'Feature flag key cannot be empty.')
+        return false
+      end
+
+      if user_id.to_s.empty?
+        @logger.log(Logger::ERROR, 'User ID cannot be empty.')
+        return false
+      end
+
       feature_flag = @config.get_feature_flag_from_key(feature_flag_key)
       unless feature_flag
         @logger.log(Logger::ERROR, "No feature flag was found for key '#{feature_flag_key}'.")

spec/project_spec.rb

@@ -659,6 +659,17 @@ class InvalidErrorHandler; end
       expect(invalid_project.is_feature_enabled('totally_invalid_feature_key', 'test_user')).to be false
     end
 
+    it 'should return false when the feature flag key is nil' do
+      expect(project_instance.is_feature_enabled(nil, 'test_user')).to be false
+      expect(spy_logger).to have_received(:log).once.with(Logger::ERROR, 'Feature flag key cannot be empty.')
+    end
+
+    it 'should return false when user_id is empty or nil' do
+      expect(project_instance.is_feature_enabled('boolean_single_variable_feature', '')).to be false
+      expect(project_instance.is_feature_enabled('boolean_single_variable_feature', nil)).to be false
+      expect(spy_logger).to have_received(:log).twice.with(Logger::ERROR, 'User ID cannot be empty.')
+    end
+
     it 'should return false when the feature flag key is invalid' do
       expect(project_instance.is_feature_enabled('totally_invalid_feature_key', 'test_user')).to be false
       expect(spy_logger).to have_received(:log).once.with(Logger::ERROR, "Feature flag key 'totally_invalid_feature_key' is not in datafile.")