Add unit tests for ts_tree_get_changed_ranges

cli/src/tests/helpers/edits.rs

@@ -0,0 +1,94 @@
+use super::random::Rand;
+use tree_sitter::{InputEdit, Point, Tree};
+
+pub struct Edit {
+    pub position: usize,
+    pub deleted_length: usize,
+    pub inserted_text: Vec<u8>,
+}
+
+pub fn perform_edit(tree: &mut Tree, input: &mut Vec<u8>, edit: &Edit) {
+    let start_byte = edit.position;
+    let old_end_byte = edit.position + edit.deleted_length;
+    let new_end_byte = edit.position + edit.inserted_text.len();
+    let start_position = position_for_offset(input, start_byte);
+    let old_end_position = position_for_offset(input, old_end_byte);
+    input.splice(start_byte..old_end_byte, edit.inserted_text.iter().cloned());
+    let new_end_position = position_for_offset(input, new_end_byte);
+    tree.edit(&InputEdit {
+        start_byte,
+        old_end_byte,
+        new_end_byte,
+        start_position,
+        old_end_position,
+        new_end_position,
+    });
+}
+
+pub fn invert_edit(input: &Vec<u8>, edit: &Edit) -> Edit {
+    let position = edit.position;
+    let removed_content = &input[position..(position + edit.deleted_length)];
+    Edit {
+        position,
+        deleted_length: edit.inserted_text.len(),
+        inserted_text: removed_content.to_vec(),
+    }
+}
+
+pub fn get_random_edit(rand: &mut Rand, input: &Vec<u8>) -> Edit {
+    let choice = rand.unsigned(10);
+    if choice < 2 {
+        // Insert text at end
+        let inserted_text = rand.words(3);
+        Edit {
+            position: input.len(),
+            deleted_length: 0,
+            inserted_text,
+        }
+    } else if choice < 5 {
+        // Delete text from the end
+        let mut deleted_length = rand.unsigned(10);
+        if deleted_length > input.len() {
+            deleted_length = input.len();
+        }
+        Edit {
+            position: input.len() - deleted_length,
+            deleted_length,
+            inserted_text: vec![],
+        }
+    } else if choice < 8 {
+        // Insert at a random position
+        let position = rand.unsigned(input.len());
+        let word_count = 1 + rand.unsigned(3);
+        let inserted_text = rand.words(word_count);
+        Edit {
+            position,
+            deleted_length: 0,
+            inserted_text,
+        }
+    } else {
+        // Replace at random position
+        let position = rand.unsigned(input.len());
+        let deleted_length = rand.unsigned(input.len() - position);
+        let word_count = 1 + rand.unsigned(3);
+        let inserted_text = rand.words(word_count);
+        Edit {
+            position,
+            deleted_length,
+            inserted_text,
+        }
+    }
+}
+
+fn position_for_offset(input: &Vec<u8>, offset: usize) -> Point {
+    let mut result = Point { row: 0, column: 0 };
+    for c in &input[0..offset] {
+        if *c as char == '\n' {
+            result.row += 1;
+            result.column = 0;
+        } else {
+            result.column += 1;
+        }
+    }
+    result
+}

cli/src/tests/helpers/mod.rs

@@ -2,3 +2,4 @@ pub(super) mod allocations;
 pub(super) mod fixtures;
 pub(super) mod random;
 pub(super) mod scope_sequence;
+pub(super) mod edits;