Correct OTLP environment variable names and add tests

vls-util/src/env_var.rs

@@ -5,14 +5,14 @@ pub fn deployment_environment() -> String {
 }
 
 pub fn otlp_endpoint() -> Option<String> {
-    env::var("OLTP_ENDPOINT").ok()
+    env::var("OTLP_ENDPOINT").ok()
 }
 
 pub fn otlp_timeout() -> u64 {
-    env::var("OLTP_TIMEOUT")
+    env::var("OTLP_TIMEOUT")
         .unwrap_or("3".to_string())
         .parse()
-        .expect("OLTP Exporter timeout value needs to be a positive number")
+        .expect("OTLP exporter timeout value needs to be a positive number")
 }
 
 pub fn compare_env_var(key: &str, value: &str) -> bool {
@@ -21,3 +21,34 @@ pub fn compare_env_var(key: &str, value: &str) -> bool {
         Err(_) => false,
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::env;
+
+    #[test]
+    fn test_otlp_env_vars() {
+        let orig_endpoint = env::var("OTLP_ENDPOINT").ok();
+        let orig_timeout = env::var("OTLP_TIMEOUT").ok();
+
+        env::remove_var("OTLP_ENDPOINT");
+        env::remove_var("OTLP_TIMEOUT");
+        assert_eq!(otlp_endpoint(), None);
+        assert_eq!(otlp_timeout(), 3);
+
+        env::set_var("OTLP_ENDPOINT", "http://localhost:4317");
+        env::set_var("OTLP_TIMEOUT", "5");
+        assert_eq!(otlp_endpoint(), Some("http://localhost:4317".to_string()));
+        assert_eq!(otlp_timeout(), 5);
+
+        match orig_endpoint {
+            Some(v) => env::set_var("OTLP_ENDPOINT", v),
+            None => env::remove_var("OTLP_ENDPOINT"),
+        }
+        match orig_timeout {
+            Some(v) => env::set_var("OTLP_TIMEOUT", v),
+            None => env::remove_var("OTLP_TIMEOUT"),
+        }
+    }
+}