it does not work actually

src/main.rs

@@ -1,12 +1,15 @@
 use std::io::{self, prelude::*};
 
 fn main() -> Result<(), io::Error> {
+    // TODO: check if stdin is empty and show usage
     let mut tty = std::fs::File::options()
         .write(true)
         .read(false)
-        .open("/dev/tty")?;
+        .open("/dev/tty")
-    io::copy(&mut io::stdin(), &mut tty)?;
+        .inspect_err(|err| eprintln!("{err}"))?;
-    tty.flush()?;
+    // FIXME: only works with cargo run?
-    io::copy(&mut io::stdin(), &mut io::stdout())?;
+    io::copy(&mut io::stdin(), &mut tty).inspect_err(|err| eprintln!("{err}"))?;
+    tty.flush().inspect_err(|err| eprintln!("{err}"))?;
+    io::copy(&mut io::stdin(), &mut io::stdout()).inspect_err(|err| eprintln!("{err}"))?;
     Ok(())
 }

tests/cli.rs

@@ -0,0 +1,4 @@
+#[test]
+fn pipe_echo_cat() {
+    todo!()
+}