Fix bugs in {prev,next}_row_boundary

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

zed/src/editor/display_map/fold_map.rs

@@ -497,6 +497,11 @@ impl Snapshot {
         self.chunks_at(FoldOffset(0)).collect()
     }
 
+    #[cfg(test)]
+    pub fn fold_count(&self) -> usize {
+        self.folds.items(&self.buffer_snapshot).len()
+    }
+
     pub fn text_summary_for_range(&self, range: Range<FoldPoint>) -> TextSummary {
         let mut summary = TextSummary::default();
 

zed/src/editor/display_map/wrap_map.rs

@@ -495,7 +495,7 @@ impl Snapshot {
     }
 
     pub fn max_point(&self) -> WrapPoint {
-        self.to_wrap_point(self.tab_snapshot.max_point())
+        self.to_wrap_point(self.tab_snapshot.max_point(), Bias::Right)
     }
 
     pub fn line_len(&self, row: u32) -> u32 {
@@ -548,9 +548,9 @@ impl Snapshot {
         TabPoint(tab_point)
     }
 
-    pub fn to_wrap_point(&self, point: TabPoint) -> WrapPoint {
+    pub fn to_wrap_point(&self, point: TabPoint, bias: Bias) -> WrapPoint {
         let mut cursor = self.transforms.cursor::<TabPoint, WrapPoint>();
-        cursor.seek(&point, Bias::Right, &());
+        cursor.seek(&point, bias, &());
         WrapPoint(cursor.sum_start().0 + (point.0 - cursor.seek_start().0))
     }
 
@@ -564,7 +564,10 @@ impl Snapshot {
             }
         }
 
-        self.to_wrap_point(self.tab_snapshot.clip_point(self.to_tab_point(point), bias))
+        self.to_wrap_point(
+            self.tab_snapshot.clip_point(self.to_tab_point(point), bias),
+            bias,
+        )
     }
 
     fn check_invariants(&self) {