Add support for if-unused and if-empty for delete_queue

lib/rabbitmq/http/client.rb

@@ -177,8 +177,12 @@ def declare_queue(vhost, name, attributes)
         decode_resource(response)
       end
 
-      def delete_queue(vhost, name)
-        decode_resource(@connection.delete("queues/#{encode_uri_path_segment(vhost)}/#{encode_uri_path_segment(name)}"))
+      def delete_queue(vhost, name, if_unused = false, if_empty = false)
+        response = @connection.delete("queues/#{encode_uri_path_segment(vhost)}/#{encode_uri_path_segment(name)}") do |req|
+          req.params["if-unused"] = true if if_unused
+          req.params["if-empty"] = true if if_empty
+        end
+        decode_resource(response)
       end
 
       def list_queue_bindings(vhost, queue, query = {})

spec/integration/api_endpoints_spec.rb

@@ -505,6 +505,32 @@ def await_event_propagation
     it "deletes a queue" do
       q = @channel.queue(queue_name, durable: false)
       subject.delete_queue("/", queue_name)
+      expect { subject.queue_info("/", queue_name) }.to raise_error(Faraday::ResourceNotFound)
+    end
+
+    it "doesn't delete non-empty queue if if-empty is set" do
+      q = @channel.queue(queue_name, durable: false)
+      q.publish("hello")
+      expect do
+        subject.delete_queue("/", queue_name, false, true)
+      end.to raise_error(Faraday::ClientError)
+
+      subject.purge_queue("/", q.name)
+      subject.delete_queue("/", queue_name, false, true)
+      expect { subject.queue_info("/", queue_name) }.to raise_error(Faraday::ResourceNotFound)
+    end
+
+    it "doesn't delete used queue if if-unused is set" do
+      q = @channel.queue(queue_name, durable: false)
+      consumer = q.subscribe
+
+      expect do
+        subject.delete_queue("/", queue_name, true, false)
+      end.to raise_error(Faraday::ClientError)
+
+      consumer.cancel
+      subject.delete_queue("/", queue_name, true, false)
+      expect { subject.queue_info("/", queue_name) }.to raise_error(Faraday::ResourceNotFound)
     end
   end