test: add format time RFC2822 test

src/builtins/time.rs

@@ -37,4 +37,13 @@ mod tests {
     fn test_time() {
         assert_eq!(Time.execute(&mut BuiltinConfig::new(), vec![]), Ok(()))
     }
+
+    #[test]
+    fn test_format_time_rfc2822() {
+        let time = chrono::Utc.with_ymd_and_hms(6969, 4, 20, 4, 20, 9).unwrap();
+        assert_eq!(
+            format_time(time, "RFC2822"),
+            "Thu, 20 Apr 6969 04:20:09 +0000"
+        )
+    }
 }