Add tests for prefix support

Author: TBThomas56

tests/numeric_prefix.rs

@@ -0,0 +1,95 @@
+use ratatui::crossterm::event::{KeyCode, KeyEvent, KeyModifiers};
+
+fn is_valid_numeric_prefix_char(c: char, current_prefix: &str) -> bool {
+    c.is_ascii_digit() && (c != '0' || !current_prefix.is_empty())
+}
+
+fn simulate_numeric_input(inputs: &[char]) -> String {
+    let mut prefix = String::new();
+
+    for &c in inputs {
+        if is_valid_numeric_prefix_char(c, &prefix) {
+            prefix.push(c);
+        } else {
+            break;
+        }
+    }
+
+    prefix
+}
+
+#[test]
+fn test_numeric_prefix_single_digit() {
+    assert_eq!(simulate_numeric_input(&['5']), "5");
+    assert_eq!(simulate_numeric_input(&['1']), "1");
+    assert_eq!(simulate_numeric_input(&['9']), "9");
+}
+
+#[test]
+fn test_numeric_prefix_multiple_digits() {
+    assert_eq!(simulate_numeric_input(&['1', '2', '3']), "123");
+    assert_eq!(simulate_numeric_input(&['4', '2']), "42");
+    assert_eq!(simulate_numeric_input(&['9', '9', '9']), "999");
+}
+
+#[test]
+fn test_numeric_prefix_zero_rules() {
+    // Zero should not be accepted as the first character
+    assert_eq!(simulate_numeric_input(&['0']), "");
+
+    // But zero should be accepted after other digits
+    assert_eq!(simulate_numeric_input(&['1', '0']), "10");
+    assert_eq!(simulate_numeric_input(&['2', '0', '5']), "205");
+}
+
+#[test]
+fn test_numeric_prefix_stops_at_non_digit() {
+    assert_eq!(simulate_numeric_input(&['5', 'j']), "5");
+    assert_eq!(simulate_numeric_input(&['1', '2', 'k']), "12");
+    assert_eq!(simulate_numeric_input(&['3', ' ']), "3");
+}
+
+#[test]
+fn test_numeric_prefix_empty_for_non_numeric_start() {
+    assert_eq!(simulate_numeric_input(&['j']), "");
+    assert_eq!(simulate_numeric_input(&['k']), "");
+    assert_eq!(simulate_numeric_input(&[' ']), "");
+}
+
+#[test]
+fn test_numeric_prefix_parsing() {
+    assert_eq!("5".parse::<usize>().unwrap_or(1), 5);
+    assert_eq!("42".parse::<usize>().unwrap_or(1), 42);
+    assert_eq!("999".parse::<usize>().unwrap_or(1), 999);
+    assert_eq!("".parse::<usize>().unwrap_or(1), 1);
+    assert_eq!("abc".parse::<usize>().unwrap_or(1), 1);
+}
+
+#[test]
+fn test_key_event_digit_detection() {
+    let digit_events = [
+        KeyEvent::new(KeyCode::Char('0'), KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Char('1'), KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Char('5'), KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Char('9'), KeyModifiers::empty()),
+    ];
+
+    for event in digit_events {
+        if let KeyCode::Char(c) = event.code {
+            assert!(c.is_ascii_digit());
+        }
+    }
+
+    let non_digit_events = [
+        KeyEvent::new(KeyCode::Char('j'), KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Char('k'), KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Enter, KeyModifiers::empty()),
+        KeyEvent::new(KeyCode::Esc, KeyModifiers::empty()),
+    ];
+
+    for event in non_digit_events {
+        if let KeyCode::Char(c) = event.code {
+            assert!(!c.is_ascii_digit())
+        }
+    }
+}