[test] add tests for --no-interaction and its alias to ensure non-interactive mode skips prompts and uses defaults

src/lib.rs

@@ -36,7 +36,17 @@ pub fn set_no_interaction(b: bool) {
 }
 /// Return current non-interactive state.
 pub fn is_no_interaction() -> bool {
-    NO_INTERACTION.load(Ordering::Relaxed)
+    if NO_INTERACTION.load(Ordering::Relaxed) {
+        return true;
+    }
+    // Also honor NO_INTERACTION=1/true environment variable for convenience/testing
+    match std::env::var("NO_INTERACTION") {
+        Ok(v) => {
+            let v = v.trim();
+            v == "1" || v.eq_ignore_ascii_case("true")
+        }
+        Err(_) => false,
+    }
 }
 
 /// Set verbose level (0 = normal, 1 = verbose, 2 = super-verbose)
@@ -638,8 +648,13 @@ where
     }
     // Print a blank line before the selection prompt to keep output synchronized.
     printer("");
-    let idx = crate::ui::prompt_select_index("Select a Whisper model", &display_names)
-        .context("Failed to read selection")?;
+    let idx = if crate::is_no_interaction() || !crate::stdin_is_tty() {
+        // Non-interactive: auto-select the first candidate deterministically (as listed)
+        0
+    } else {
+        crate::ui::prompt_select_index("Select a Whisper model", &display_names)
+            .context("Failed to read selection")?
+    };
     let chosen = candidates.swap_remove(idx);
     let _ = std::fs::write(models_dir.join(".last_model"), chosen.display().to_string());
     // Print an empty line after selection input