fix: crash on surround delete when direction is backward

`find_nth_closest_pairs_pos` produces unsorted tuple. Need to sort it before passing tuple to the delete transaction.

helix-editor#6626

helix-core/src/surround.rs

@@ -1,4 +1,4 @@
-use std::fmt::Display;
+use std::{cmp, fmt::Display};
 
 use crate::{movement::Direction, search, Range, Selection};
 use ropey::RopeSlice;
@@ -52,6 +52,9 @@ pub fn get_pair(ch: char) -> (char, char) {
         .unwrap_or((ch, ch))
 }
 
+/// Find the position of surround pairs of any [`PAIRS`].
+///
+/// Be careful, the second position in return tuple can be to the left of the first position if the range is backward.
 pub fn find_nth_closest_pairs_pos(
     text: RopeSlice,
     range: Range,
@@ -253,10 +256,18 @@ pub fn get_surround_pos(
     let mut change_pos = Vec::new();
 
     for &range in selection {
-        let (open_pos, close_pos) = match ch {
-            Some(ch) => find_nth_pairs_pos(text, ch, range, skip)?,
-            None => find_nth_closest_pairs_pos(text, range, skip)?,
+        let (open_pos, close_pos) = {
+            let (lhs, rhs) = match ch {
+                Some(ch) => find_nth_pairs_pos(text, ch, range, skip)?,
+                None => find_nth_closest_pairs_pos(text, range, skip)?,
+            };
+            // If the direction of the range is backward, the second value is to the left of the first.
+            (cmp::min(lhs, rhs), cmp::max(lhs, rhs))
         };
+
+        // WARN this will not find overlaps when use `m` (None) as find character.
+        // E.g. "(  < c (   > c )   )", c - cursor. Change_pos = [3, 11, 7, 15].
+        // Overlaps occurs but this condition didn't find it because pairs have different open/close chars.
         if change_pos.contains(&open_pos) || change_pos.contains(&close_pos) {
             return Err(Error::CursorOverlap);
         }

helix-term/tests/test/commands.rs

@@ -480,3 +480,12 @@ fn bar() {#(\n|)#\
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread")]
+async fn surround_delete() -> anyhow::Result<()> {
+    // Test `surround_delete` when head < anchor
+    test(("(#[|  ]#)", "mdm", "#[|  ]#")).await?;
+    test(("(#[|  ]#)", "md(", "#[|  ]#")).await?;
+
+    Ok(())
+}