Avoid env mutation in telemetry test

Signed-off-by: Jaap Frolich <jfrolich@gmail.com>

Author: jfrolich

rewatch/src/telemetry.rs

@@ -51,10 +51,18 @@ impl Drop for TelemetryGuard {
 /// tracing calls become no-ops.
 pub fn init_telemetry() -> TelemetryGuard {
     // Presence of either the general or trace-specific endpoint env var enables OTLP export.
-    let enabled = std::env::var_os("OTEL_EXPORTER_OTLP_ENDPOINT").is_some()
-        || std::env::var_os("OTEL_EXPORTER_OTLP_TRACES_ENDPOINT").is_some();
+    init_telemetry_for_endpoint_presence(
+        std::env::var_os("OTEL_EXPORTER_OTLP_ENDPOINT").is_some(),
+        std::env::var_os("OTEL_EXPORTER_OTLP_TRACES_ENDPOINT").is_some(),
+    )
+}
 
-    if enabled { init_with_otlp() } else { init_noop() }
+fn init_telemetry_for_endpoint_presence(endpoint_set: bool, traces_endpoint_set: bool) -> TelemetryGuard {
+    if endpoint_set || traces_endpoint_set {
+        init_with_otlp()
+    } else {
+        init_noop()
+    }
 }
 
 /// Initialize with OTLP exporter.
@@ -146,16 +154,7 @@ mod tests {
 
     #[test]
     fn init_telemetry_without_env_is_noop() {
-        // SAFETY: These env vars are process-global; tests run serially in a
-        // single thread by default for this crate (no #[test(flavor = ...)]).
-        // If parallelised later, wrap in a Mutex.
-        // Ensure the env is clean for this check.
-        unsafe {
-            std::env::remove_var("OTEL_EXPORTER_OTLP_ENDPOINT");
-            std::env::remove_var("OTEL_EXPORTER_OTLP_TRACES_ENDPOINT");
-        }
-
-        let guard = init_telemetry();
+        let guard = init_telemetry_for_endpoint_presence(false, false);
         assert!(
             !guard.otel_enabled(),
             "expected no-op guard when OTEL endpoint env vars are unset"