add: log test helper

src/bin/test-helper/log.rs

@@ -0,0 +1,19 @@
+use std::env;
+use std::fs;
+use std::io;
+use std::io::Write;
+use time::OffsetDateTime;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let args: Vec<String> = env::args().collect(); 
+
+    if args.len() == 3 {
+        let file = fs::OpenOptions::new().create(true).append(true).open(&args[1])?;
+        let mut buf = io::BufWriter::new(file);
+        let local_time = OffsetDateTime::now_local()?;
+        buf.write_all(format!("{} {}\n", local_time, &args[2]).as_bytes())?;
+    } else {
+        return Err(anyhow::anyhow!("invalid argument").into());
+    }
+    Ok(())
+}