From dbee036ce654ca3259c7033b6e7e9a9a1050c137 Mon Sep 17 00:00:00 2001
From: rhysd <lin90162@yahoo.co.jp>
Date: Mon, 18 Jul 2022 11:43:30 +0900
Subject: [PATCH] support generating random `CursorMove` with `arbitrary`

---
 fuzz/Cargo.toml           |  2 +-
 fuzz/fuzz_targets/edit.rs | 28 +++++++++++++++++++++-------
 src/cursor.rs             |  3 +++
 3 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/fuzz/Cargo.toml b/fuzz/Cargo.toml
index d726232..6f2c0ca 100644
--- a/fuzz/Cargo.toml
+++ b/fuzz/Cargo.toml
@@ -10,7 +10,7 @@ cargo-fuzz = true
 
 [dependencies]
 libfuzzer-sys = "0.4"
-arbitrary = "1"
+arbitrary = { version = "1", features = ["derive"] }
 tui-textarea = { path = "..", features = ["search", "arbitrary"] }
 tui-textarea-bench = { path = "../bench" }
 
diff --git a/fuzz/fuzz_targets/edit.rs b/fuzz/fuzz_targets/edit.rs
index 92a5fe3..2300b09 100644
--- a/fuzz/fuzz_targets/edit.rs
+++ b/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(())
diff --git a/src/cursor.rs b/src/cursor.rs
index a25430e..260a949 100644
--- a/src/cursor.rs
+++ b/src/cursor.rs
@@ -1,8 +1,11 @@
 use crate::word::{find_word_start_backward, find_word_start_forward};
+#[cfg(feature = "arbitrary")]
+use arbitrary::Arbitrary;
 use std::cmp;
 
 /// Specify how to move the cursor.
 #[derive(Clone, Copy, Debug)]
+#[cfg_attr(feature = "arbitrary", derive(Arbitrary))]
 pub enum CursorMove {
     /// Move cursor forward by one character. When the cursor is at the end of line, it moves to the head of next line.
     /// ```