Implement Default for a number of structs in responses

without these defaults, a request that hits a freshly
booted RabbitMQ node would panic because one of the
metrics/rates fields would be missing, because
some statistics tracking events haven't yet happened.

Author: michaelklishin

src/responses.rs

@@ -1864,7 +1864,8 @@ pub struct MessageRouted {
 #[serde(transparent)]
 pub struct MessageProperties(pub Map<String, serde_json::Value>);
 
-#[derive(Debug, Deserialize, Clone, Eq, PartialEq)]
+#[derive(Debug, Deserialize, Clone, Eq, PartialEq, Default)]
+#[serde(default)]
 #[cfg_attr(feature = "tabled", derive(Tabled))]
 pub struct ChurnRates {
     pub connection_created: u32,
@@ -1876,13 +1877,15 @@ pub struct ChurnRates {
     pub channel_closed: u32,
 }
 
-#[derive(Debug, Deserialize, Clone, PartialEq, PartialOrd)]
+#[derive(Debug, Deserialize, Clone, PartialEq, PartialOrd, Default)]
+#[serde(default)]
 #[cfg_attr(feature = "tabled", derive(Tabled))]
 pub struct Rate {
     pub rate: f64,
 }
 
-#[derive(Debug, Deserialize, Clone, Eq, PartialEq)]
+#[derive(Debug, Deserialize, Clone, Eq, PartialEq, Default)]
+#[serde(default)]
 #[cfg_attr(feature = "tabled", derive(Tabled))]
 pub struct ObjectTotals {
     pub connections: u64,
@@ -1892,50 +1895,51 @@ pub struct ObjectTotals {
     pub consumers: u64,
 }
 
-#[derive(Debug, Deserialize, Clone, PartialEq)]
+#[derive(Debug, Deserialize, Clone, PartialEq, Default)]
+#[serde(default)]
 #[cfg_attr(feature = "tabled", derive(Tabled))]
 pub struct QueueTotals {
     pub messages: u64,
-    #[serde(rename = "messages_ready")]
+    #[serde(rename = "messages_ready", default)]
     pub messages_ready_for_delivery: u64,
-    #[serde(rename = "messages_unacknowledged")]
+    #[serde(rename = "messages_unacknowledged", default)]
     pub messages_delivered_but_unacknowledged_by_consumers: u64,
     pub messages_details: Rate,
-    #[serde(rename = "messages_ready_details")]
+    #[serde(rename = "messages_ready_details", default)]
     pub messages_ready_for_delivery_details: Rate,
-    #[serde(rename = "messages_unacknowledged_details")]
+    #[serde(rename = "messages_unacknowledged_details", default)]
     pub messages_delivered_but_unacknowledged_by_consumers_details: Rate,
 }
 
-#[derive(Debug, Deserialize, Clone, PartialEq)]
+#[derive(Debug, Deserialize, Clone, PartialEq, Default)]
 #[cfg_attr(feature = "tabled", derive(Tabled))]
 pub struct MessageStats {
     /// Consumer delivery rate plus polling (via 'basic.get') rate
-    #[serde(rename = "deliver_get_details")]
+    #[serde(rename = "deliver_get_details", default)]
     #[cfg_attr(feature = "tabled", tabled(display = "display_option"))]
     pub delivery_details: Option<Rate>,
-    #[serde(rename = "publish_details")]
+    #[serde(rename = "publish_details", default)]
     #[cfg_attr(feature = "tabled", tabled(display = "display_option"))]
     pub publishing_details: Option<Rate>,
 
-    #[serde(rename = "deliver_no_ack_details")]
+    #[serde(rename = "deliver_no_ack_details", default)]
     #[cfg_attr(feature = "tabled", tabled(display = "display_option"))]
     pub delivery_with_automatic_acknowledgement_details: Option<Rate>,
-    #[serde(rename = "redeliver_details")]
+    #[serde(rename = "redeliver_details", default)]
     #[cfg_attr(feature = "tabled", tabled(display = "display_option"))]
     pub redelivery_details: Option<Rate>,
 
-    #[serde(rename = "confirm_details")]
+    #[serde(rename = "confirm_details", default)]
     #[cfg_attr(feature = "tabled", tabled(display = "display_option"))]
     pub publisher_confirmation_details: Option<Rate>,
-    #[serde(rename = "ack_details")]
+    #[serde(rename = "ack_details", default)]
     #[cfg_attr(feature = "tabled", tabled(display = "display_option"))]
     pub consumer_acknowledgement_details: Option<Rate>,
 
-    #[serde(rename = "drop_unroutable_details")]
+    #[serde(rename = "drop_unroutable_details", default)]
     #[cfg_attr(feature = "tabled", tabled(display = "display_option"))]
     pub unroutable_dropped_message_details: Option<Rate>,
-    #[serde(rename = "return_unroutable_details")]
+    #[serde(rename = "return_unroutable_details", default)]
     #[cfg_attr(feature = "tabled", tabled(display = "display_option"))]
     pub unroutable_returned_message_details: Option<Rate>,
 }
@@ -1954,7 +1958,8 @@ pub struct Listener {
 #[serde(transparent)]
 pub struct TagMap(pub Map<String, serde_json::Value>);
 
-#[derive(Debug, Deserialize, Clone, PartialEq)]
+#[derive(Debug, Deserialize, Clone, PartialEq, Default)]
+#[serde(default)]
 #[cfg_attr(feature = "tabled", derive(Tabled))]
 pub struct Overview {
     pub cluster_name: String,

tests/unit_default_tests.rs

@@ -0,0 +1,24 @@
+// Copyright (C) 2023-2025 RabbitMQ Core Team ([email protected])
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+mod test_helpers;
+
+use rabbitmq_http_client::responses::Rate;
+
+#[test]
+fn test_unit_default_rate() {
+    let def = Rate::default();
+
+    // Specifically for this test, we don't really need to use `approx`
+    assert_eq!(def.rate, 0.0);
+}