Add tests

autometrics/Cargo.toml

@@ -58,7 +58,7 @@ axum = { version = "0.6", features = ["tokio"] }
 http = "0.2"
 tokio = { version = "1", features = ["full"] }
 tracing = "0.1"
-tracing-subscriber = { version = "0.3", default-features = false }
+tracing-subscriber = "0.3"
 trybuild = "1.0"
 uuid = { version = "1", features = ["v4"] }
 vergen = { version = "8.1", features = ["git", "gitcl"] }

autometrics/src/exemplars/tracing.rs

@@ -128,4 +128,10 @@ impl Visit for TraceLabelVisitor {
             self.labels.insert(field.name(), format!("{:?}", value));
         }
     }
+
+    fn record_str(&mut self, field: &Field, value: &str) {
+        if self.fields.contains(&field.name()) && !self.labels.contains_key(field.name()) {
+            self.labels.insert(field.name(), value.to_string());
+        }
+    }
 }

autometrics/tests/exemplars_test.rs

@@ -0,0 +1,53 @@
+use autometrics::exemplars::tracing::AutometricsExemplarExtractor;
+use autometrics::{autometrics, encode_global_metrics, global_metrics_exporter};
+use tracing::instrument;
+use tracing_subscriber::prelude::*;
+
+#[cfg(all(feature = "exemplars-tracing", feature = "prometheus-exporter"))]
+#[test]
+fn single_field() {
+    let _ = global_metrics_exporter();
+
+    #[autometrics]
+    #[instrument(fields(trace_id = "test_trace_id"))]
+    fn single_field_fn() {}
+
+    let subscriber = tracing_subscriber::fmt::fmt()
+        .finish()
+        .with(AutometricsExemplarExtractor::from_fields(&["trace_id"]));
+    tracing::subscriber::with_default(subscriber, || single_field_fn());
+
+    let metrics = encode_global_metrics().unwrap();
+    assert!(metrics.lines().any(|line| {
+        line.starts_with("function_calls_count_total{")
+            && line.contains(r#"function="single_field_fn""#)
+            && line.ends_with(r#"} 1 # {trace_id="test_trace_id"} 1.0"#)
+    }))
+}
+
+#[cfg(all(feature = "exemplars-tracing", feature = "prometheus-exporter"))]
+#[test]
+fn multiple_fields() {
+    let _ = global_metrics_exporter();
+
+    #[autometrics]
+    #[instrument(fields(trace_id = "test_trace_id", foo = 99))]
+    fn multiple_fields_fn() {}
+
+    let subscriber =
+        tracing_subscriber::fmt::fmt()
+            .finish()
+            .with(AutometricsExemplarExtractor::from_fields(&[
+                "trace_id", "foo",
+            ]));
+    tracing::subscriber::with_default(subscriber, || multiple_fields_fn());
+
+    let metrics = encode_global_metrics().unwrap();
+    println!("{}", metrics);
+    assert!(metrics.lines().any(|line| {
+        line.starts_with("function_calls_count_total{")
+            && line.contains(r#"function="multiple_fields_fn""#)
+            && (line.ends_with(r#"} 1 # {trace_id="test_trace_id",foo="99"} 1.0"#)
+                || line.ends_with(r#"} 1 # {foo="99",trace_id="test_trace_id"} 1.0"#))
+    }))
+}