Add test & changelog

Signed-off-by: Jean-Baptiste Skutnik <[email protected]>

Author: spoutn1k

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+- Filter out empty metric families, to match the go client.
+
 ## [0.24.0]
 
 ### Added

src/encoding/text.rs

@@ -37,14 +37,13 @@
 //! assert_eq!(expected_msg, buffer);
 //! ```
 
-use crate::encoding::{EncodeExemplarTime, EncodeExemplarValue, EncodeLabelSet, NoLabelSet};
-use crate::metrics::exemplar::Exemplar;
-use crate::metrics::MetricType;
-use crate::registry::{Prefix, Registry, Unit};
+use crate::{
+    encoding::{EncodeExemplarTime, EncodeExemplarValue, EncodeLabelSet, NoLabelSet},
+    metrics::{MetricType, exemplar::Exemplar},
+    registry::{Prefix, Registry, Unit},
+};
 
-use std::borrow::Cow;
-use std::collections::HashMap;
-use std::fmt::Write;
+use std::{borrow::Cow, collections::HashMap, fmt::Write};
 
 /// Encode both the metrics registered with the provided [`Registry`] and the
 /// EOF marker into the provided [`Write`]r using the OpenMetrics text format.
@@ -736,17 +735,21 @@ impl std::fmt::Write for LabelValueEncoder<'_> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::metrics::exemplar::HistogramWithExemplars;
-    use crate::metrics::family::Family;
-    use crate::metrics::gauge::Gauge;
-    use crate::metrics::histogram::{exponential_buckets, Histogram};
-    use crate::metrics::info::Info;
-    use crate::metrics::{counter::Counter, exemplar::CounterWithExemplar};
+    use crate::metrics::{
+        counter::Counter,
+        exemplar::{CounterWithExemplar, HistogramWithExemplars},
+        family::Family,
+        gauge::Gauge,
+        histogram::{Histogram, exponential_buckets},
+        info::Info,
+    };
     use pyo3::{prelude::*, types::PyModule};
-    use std::borrow::Cow;
-    use std::fmt::Error;
-    use std::sync::atomic::{AtomicI32, AtomicU32};
-    use std::time::{SystemTime, UNIX_EPOCH};
+    use std::{
+        borrow::Cow,
+        fmt::Error,
+        sync::atomic::{AtomicI32, AtomicU32},
+        time::{SystemTime, UNIX_EPOCH},
+    };
 
     #[test]
     fn encode_counter() {
@@ -893,8 +896,7 @@ mod tests {
 
         encode(&mut encoded, &registry).unwrap();
 
-        let expected = "# HELP my_prefix_my_counter_family My counter family.\n"
-            .to_owned()
+        let expected = "# HELP my_prefix_my_counter_family My counter family.\n".to_owned()
             + "# TYPE my_prefix_my_counter_family counter\n"
             + "my_prefix_my_counter_family_total{my_key=\"my_value\",method=\"GET\",status=\"200\"} 1\n"
             + "# EOF\n";
@@ -1278,4 +1280,41 @@ def parse(input):
                 .unwrap();
         })
     }
+
+    #[test]
+    fn encode_omit_empty() {
+        let mut registry = Registry::default();
+        let counter1: Family<Vec<(&'static str, &'static str)>, Counter> = Default::default();
+        let counter2: Family<Vec<(&'static str, &'static str)>, Counter> = Default::default();
+        let counter3: Family<Vec<(&'static str, &'static str)>, Counter> = Default::default();
+
+        registry.register("counter1", "First counter", counter1.clone());
+        registry.register("counter2", "Second counter", counter2.clone());
+        registry.register("counter3", "Third counter", counter3.clone());
+
+        counter1.get_or_create(&vec![("label", "value")]).inc();
+
+        let mut encoded = String::new();
+        encode(&mut encoded, &registry).unwrap();
+
+        let expected = "# HELP counter1 First counter.\n".to_owned()
+            + "# TYPE counter1 counter\n"
+            + "counter1_total{label=\"value\"} 1\n"
+            + "# EOF\n";
+        assert_eq!(expected, encoded);
+
+        counter2.get_or_create(&vec![("label", "value")]).inc();
+
+        let mut encoded = String::new();
+        encode(&mut encoded, &registry).unwrap();
+
+        let expected = "# HELP counter1 First counter.\n".to_owned()
+            + "# TYPE counter1 counter\n"
+            + "counter1_total{label=\"value\"} 1\n"
+            + "# HELP counter2 Second counter.\n"
+            + "# TYPE counter2 counter\n"
+            + "counter2_total{label=\"value\"} 1\n"
+            + "# EOF\n";
+        assert_eq!(expected, encoded);
+    }
 }