test(action): add unit tests for Action conversions

- Implement tests for converting chars to Actions
- Verify correct parsing of move and push actions
- Test error handling for invalid inputs
- Add tests for converting Actions back to chars

tests/action.rs

@@ -0,0 +1,18 @@
+use soukoban::{direction::Direction, Action};
+
+#[test]
+fn action_from_char() {
+    assert_eq!(Action::try_from('u'), Ok(Action::Move(Direction::Up)));
+    assert_eq!(Action::try_from('d'), Ok(Action::Move(Direction::Down)));
+
+    assert_eq!(Action::try_from('U'), Ok(Action::Push(Direction::Up)));
+    assert_eq!(Action::try_from('D'), Ok(Action::Push(Direction::Down)));
+
+    assert!(Action::try_from('x').is_err());
+}
+
+#[test]
+fn action_to_char() {
+    assert_eq!(char::from(Action::Move(Direction::Up)), 'u');
+    assert_eq!(char::from(Action::Push(Direction::Up)), 'U');
+}