Add deterministic test & extract time formatter for list_files (#616)

src/root/ifconfig.rs

@@ -473,7 +473,7 @@ fn run_command(cmd: &str, args: &[&str]) -> Result<bool> {
 mod tests {
     use std::{
         path::{Path, PathBuf},
-        time::{SystemTime, UNIX_EPOCH},
+        time::{Duration, SystemTime, UNIX_EPOCH},
     };
 
     use super::*;
@@ -684,6 +684,59 @@ mod tests {
         fs::remove_dir_all(&dir).expect("temp test directory should be removable");
     }
 
+    const LIST_FILES_MTIME_CHILD_ENV: &str = "ROXY_LIST_FILES_MTIME_CHILD";
+
+    #[test]
+    fn list_files_formats_modified_time_in_local_timezone() {
+        if std::env::var_os(LIST_FILES_MTIME_CHILD_ENV).is_some() {
+            let dir = make_temp_test_dir("list-mtime");
+            let file_path = dir.join("fixed.yaml");
+            write_text_file(&file_path, "fixed");
+
+            let ts = UNIX_EPOCH + Duration::from_secs(1_700_000_000);
+            let file = OpenOptions::new()
+                .write(true)
+                .open(&file_path)
+                .expect("test file should be openable for timestamp update");
+            file.set_modified(ts)
+                .expect("test file modified time should be settable");
+
+            let listed = list_files(
+                dir.to_str().expect("temp path should be valid utf-8"),
+                None,
+                false,
+            )
+            .expect("listing files should succeed");
+            assert_eq!(
+                listed,
+                vec![(
+                    5,
+                    "2023/11/14 22:13:20".to_string(),
+                    "fixed.yaml".to_string()
+                )]
+            );
+
+            fs::remove_dir_all(&dir).expect("temp test directory should be removable");
+            return;
+        }
+
+        let output = std::process::Command::new(
+            std::env::current_exe().expect("current test executable should be available"),
+        )
+        .arg("list_files_formats_modified_time_in_local_timezone")
+        .env(LIST_FILES_MTIME_CHILD_ENV, "1")
+        .env("TZ", "UTC")
+        .output()
+        .expect("child test process should run");
+
+        assert!(
+            output.status.success(),
+            "child test process should pass\nstdout:\n{}\nstderr:\n{}",
+            String::from_utf8_lossy(&output.stdout),
+            String::from_utf8_lossy(&output.stderr)
+        );
+    }
+
     #[test]
     fn list_files_fails_for_missing_directory() {
         let dir = make_temp_test_dir("list-missing");