support generating random CursorMove with arbitrary

fuzz/fuzz_targets/edit.rs

@@ -2,21 +2,35 @@
 
 use arbitrary::{Arbitrary, Result, Unstructured};
 use libfuzzer_sys::fuzz_target;
-use std::iter;
 use std::str;
-use tui_textarea::{Input, TextArea};
+use tui_textarea::{CursorMove, Input, TextArea};
 use tui_textarea_bench::{dummy_terminal, TerminalExt};
 
+#[derive(Arbitrary)]
+enum RandomInput {
+    Input(Input),
+    Cursor(CursorMove),
+}
+
+impl RandomInput {
+    fn apply(self, t: &mut TextArea<'_>) {
+        match self {
+            Self::Input(input) => {
+                t.input(input);
+            }
+            Self::Cursor(m) => t.move_cursor(m),
+        }
+    }
+}
+
 fn fuzz(data: &[u8]) -> Result<()> {
     let mut term = dummy_terminal();
     let mut data = Unstructured::new(data);
-    let inputs: Vec<_> = iter::repeat_with(|| Input::arbitrary(&mut data))
-        .take(100)
-        .collect::<Result<_>>()?;
     let text = <&str>::arbitrary(&mut data)?;
     let mut textarea = TextArea::from(text.lines());
-    for input in inputs {
-        textarea.input(input);
+    for _ in 0..100 {
+        let input = RandomInput::arbitrary(&mut data)?;
+        input.apply(&mut textarea);
         term.draw_textarea(&mut textarea);
     }
     Ok(())