diff --git a/cli/src/tests/corpus_test.rs b/cli/src/tests/corpus_test.rs
index 1ee3ddc1..f1990963 100644
--- a/cli/src/tests/corpus_test.rs
+++ b/cli/src/tests/corpus_test.rs
@@ -1,4 +1,5 @@
 use super::helpers::allocations;
+use super::helpers::edits::{get_random_edit, invert_edit, perform_edit};
 use super::helpers::fixtures::{fixtures_dir, get_language, get_test_language};
 use super::helpers::random::Rand;
 use super::helpers::scope_sequence::ScopeSequence;
@@ -7,7 +8,7 @@ use crate::test::{parse_tests, print_diff, print_diff_key, TestEntry};
 use crate::util;
 use lazy_static::lazy_static;
 use std::{env, fs, time, usize};
-use tree_sitter::{InputEdit, LogType, Node, Parser, Point, Tree};
+use tree_sitter::{LogType, Node, Parser, Tree};
 
 const EDIT_COUNT: usize = 3;
 const TRIAL_COUNT: usize = 10;
@@ -187,12 +188,6 @@ fn test_real_language_corpus_files() {
     }
 }
 
-struct Edit {
-    position: usize,
-    deleted_length: usize,
-    inserted_text: Vec<u8>,
-}
-
 #[test]
 fn test_feature_corpus_files() {
     let test_grammars_dir = fixtures_dir().join("test_grammars");
@@ -279,92 +274,6 @@ fn test_feature_corpus_files() {
     }
 }
 
-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 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(),
-    }
-}
-
-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,
-    });
-}
-
-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
-}
-
 fn check_consistent_sizes(tree: &Tree, input: &Vec<u8>) {
     fn check(node: Node, line_offsets: &Vec<usize>) {
         let start_byte = node.start_byte();
diff --git a/cli/src/tests/helpers/edits.rs b/cli/src/tests/helpers/edits.rs
new file mode 100644
index 00000000..4e4d0c25
--- /dev/null
+++ b/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
+}
diff --git a/cli/src/tests/helpers/mod.rs b/cli/src/tests/helpers/mod.rs
index bd5c6517..2d1ce574 100644
--- a/cli/src/tests/helpers/mod.rs
+++ b/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;
diff --git a/cli/src/tests/parser_test.rs b/cli/src/tests/parser_test.rs
index a061d8c6..43fbbc1b 100644
--- a/cli/src/tests/parser_test.rs
+++ b/cli/src/tests/parser_test.rs
@@ -30,7 +30,7 @@ fn test_basic_parsing() {
 }
 
 #[test]
-fn test_logging() {
+fn test_parsing_with_logging() {
     let mut parser = Parser::new();
     parser.set_language(rust()).unwrap();
 
@@ -57,43 +57,7 @@ fn test_logging() {
 }
 
 #[test]
-fn test_tree_cursor() {
-    let mut parser = Parser::new();
-    parser.set_language(rust()).unwrap();
-
-    let tree = parser
-        .parse_str(
-            "
-                struct Stuff {
-                    a: A;
-                    b: Option<B>,
-                }
-            ",
-            None,
-        )
-        .unwrap();
-
-    let mut cursor = tree.walk();
-    assert_eq!(cursor.node().kind(), "source_file");
-
-    assert!(cursor.goto_first_child());
-    assert_eq!(cursor.node().kind(), "struct_item");
-
-    assert!(cursor.goto_first_child());
-    assert_eq!(cursor.node().kind(), "struct");
-    assert_eq!(cursor.node().is_named(), false);
-
-    assert!(cursor.goto_next_sibling());
-    assert_eq!(cursor.node().kind(), "type_identifier");
-    assert_eq!(cursor.node().is_named(), true);
-
-    assert!(cursor.goto_next_sibling());
-    assert_eq!(cursor.node().kind(), "field_declaration_list");
-    assert_eq!(cursor.node().is_named(), true);
-}
-
-#[test]
-fn test_custom_utf8_input() {
+fn test_parsing_with_custom_utf8_input() {
     let mut parser = Parser::new();
     parser.set_language(rust()).unwrap();
 
@@ -126,7 +90,7 @@ fn test_custom_utf8_input() {
 }
 
 #[test]
-fn test_custom_utf16_input() {
+fn test_parsing_with_custom_utf16_input() {
     let mut parser = Parser::new();
     parser.set_language(rust()).unwrap();
 
@@ -162,19 +126,7 @@ fn test_custom_utf16_input() {
 }
 
 #[test]
-fn test_node_equality() {
-    let mut parser = Parser::new();
-    parser.set_language(rust()).unwrap();
-    let tree = parser.parse_str("struct A {}", None).unwrap();
-    let node1 = tree.root_node();
-    let node2 = tree.root_node();
-    assert_eq!(node1, node2);
-    assert_eq!(node1.child(0).unwrap(), node2.child(0).unwrap());
-    assert_ne!(node1.child(0).unwrap(), node2);
-}
-
-#[test]
-fn test_editing() {
+fn test_parsing_after_editing() {
     let mut parser = Parser::new();
     parser.set_language(rust()).unwrap();
 
@@ -256,7 +208,7 @@ fn test_editing() {
 }
 
 #[test]
-fn test_parallel_parsing() {
+fn test_parsing_on_multiple_threads() {
     // Parse this source file so that each thread has a non-trivial amount of
     // work to do.
     let this_file_source = include_str!("parser_test.rs");
diff --git a/cli/src/tests/tree_test.rs b/cli/src/tests/tree_test.rs
index 401ff03a..d3a16cba 100644
--- a/cli/src/tests/tree_test.rs
+++ b/cli/src/tests/tree_test.rs
@@ -1,10 +1,12 @@
+use super::helpers::edits::{invert_edit, perform_edit, Edit};
 use super::helpers::fixtures::get_language;
-use tree_sitter::{InputEdit, Language, Parser, Point};
+use std::str;
+use tree_sitter::{InputEdit, Parser, Point, Range, Tree};
 
 #[test]
-fn test_edit() {
+fn test_tree_edit() {
     let mut parser = Parser::new();
-    parser.set_language(javascript()).unwrap();
+    parser.set_language(get_language("javascript")).unwrap();
     let tree = parser.parse_str("  abc  !==  def", None).unwrap();
 
     assert_eq!(
@@ -186,6 +188,192 @@ fn test_edit() {
     }
 }
 
-fn javascript() -> Language {
-    get_language("javascript")
+#[test]
+fn test_tree_walk() {
+    let mut parser = Parser::new();
+    parser.set_language(get_language("rust")).unwrap();
+
+    let tree = parser
+        .parse_str(
+            "
+                struct Stuff {
+                    a: A;
+                    b: Option<B>,
+                }
+            ",
+            None,
+        )
+        .unwrap();
+
+    let mut cursor = tree.walk();
+    assert_eq!(cursor.node().kind(), "source_file");
+
+    assert!(cursor.goto_first_child());
+    assert_eq!(cursor.node().kind(), "struct_item");
+
+    assert!(cursor.goto_first_child());
+    assert_eq!(cursor.node().kind(), "struct");
+    assert_eq!(cursor.node().is_named(), false);
+
+    assert!(cursor.goto_next_sibling());
+    assert_eq!(cursor.node().kind(), "type_identifier");
+    assert_eq!(cursor.node().is_named(), true);
+
+    assert!(cursor.goto_next_sibling());
+    assert_eq!(cursor.node().kind(), "field_declaration_list");
+    assert_eq!(cursor.node().is_named(), true);
+}
+
+#[test]
+fn test_tree_node_equality() {
+    let mut parser = Parser::new();
+    parser.set_language(get_language("rust")).unwrap();
+    let tree = parser.parse_str("struct A {}", None).unwrap();
+    let node1 = tree.root_node();
+    let node2 = tree.root_node();
+    assert_eq!(node1, node2);
+    assert_eq!(node1.child(0).unwrap(), node2.child(0).unwrap());
+    assert_ne!(node1.child(0).unwrap(), node2);
+}
+
+#[test]
+fn test_get_changed_ranges() {
+    let source_code = b"{a: null};\n".to_vec();
+
+    let mut parser = Parser::new();
+    parser.set_language(get_language("javascript")).unwrap();
+    let tree = parser
+        .parse_utf8(&mut |i, _| &source_code[i..], None)
+        .unwrap();
+
+    assert_eq!(
+        tree.root_node().to_sexp(),
+        "(program (expression_statement (object (pair (property_identifier) (null)))))"
+    );
+
+    // Updating one token
+    {
+        let mut tree = tree.clone();
+        let mut source_code = source_code.clone();
+
+        // Replace `null` with `nothing` - that token has changed syntax
+        let edit = Edit {
+            position: index_of(&source_code, "ull"),
+            deleted_length: 3,
+            inserted_text: b"othing".to_vec(),
+        };
+        let inverse_edit = invert_edit(&source_code, &edit);
+        let ranges = get_changed_ranges(&mut parser, &mut tree, &mut source_code, edit);
+        assert_eq!(ranges, vec![range_of(&source_code, "nothing")]);
+
+        // Replace `nothing` with `null` - that token has changed syntax
+        let ranges = get_changed_ranges(&mut parser, &mut tree, &mut source_code, inverse_edit);
+        assert_eq!(ranges, vec![range_of(&source_code, "null")]);
+    }
+
+    // Changing only leading whitespace
+    {
+        let mut tree = tree.clone();
+        let mut source_code = source_code.clone();
+
+        // Insert leading newline - no changed ranges
+        let edit = Edit {
+            position: 0,
+            deleted_length: 0,
+            inserted_text: b"\n".to_vec(),
+        };
+        let inverse_edit = invert_edit(&source_code, &edit);
+        let ranges = get_changed_ranges(&mut parser, &mut tree, &mut source_code, edit);
+        assert_eq!(ranges, vec![]);
+
+        // Remove leading newline - no changed ranges
+        let ranges = get_changed_ranges(&mut parser, &mut tree, &mut source_code, inverse_edit);
+        assert_eq!(ranges, vec![]);
+    }
+
+    // Inserting elements
+    {
+        let mut tree = tree.clone();
+        let mut source_code = source_code.clone();
+
+        // Insert a key-value pair before the `}` - those tokens are changed
+        let edit1 = Edit {
+            position: index_of(&source_code, "}"),
+            deleted_length: 0,
+            inserted_text: b", b: false".to_vec(),
+        };
+        let inverse_edit1 = invert_edit(&source_code, &edit1);
+        let ranges = get_changed_ranges(&mut parser, &mut tree, &mut source_code, edit1);
+        assert_eq!(ranges, vec![range_of(&source_code, ", b: false")]);
+
+        let edit2 = Edit {
+            position: index_of(&source_code, ", b"),
+            deleted_length: 0,
+            inserted_text: b", c: 1".to_vec(),
+        };
+        let inverse_edit2 = invert_edit(&source_code, &edit2);
+        let ranges = get_changed_ranges(&mut parser, &mut tree, &mut source_code, edit2);
+        assert_eq!(ranges, vec![range_of(&source_code, ", c: 1")]);
+
+        // Remove the middle pair
+        let ranges = get_changed_ranges(&mut parser, &mut tree, &mut source_code, inverse_edit2);
+        assert_eq!(ranges, vec![]);
+
+        // Remove the second pair
+        let ranges = get_changed_ranges(&mut parser, &mut tree, &mut source_code, inverse_edit1);
+        assert_eq!(ranges, vec![]);
+    }
+
+    // Wrapping elements in larger expressions
+    {
+        let mut tree = tree.clone();
+        let mut source_code = source_code.clone();
+
+        // Replace `null` with the binary expression `b === null`
+        let edit1 = Edit {
+            position: index_of(&source_code, "null"),
+            deleted_length: 0,
+            inserted_text: b"b === ".to_vec(),
+        };
+        let inverse_edit1 = invert_edit(&source_code, &edit1);
+        let ranges = get_changed_ranges(&mut parser, &mut tree, &mut source_code, edit1);
+        assert_eq!(ranges, vec![range_of(&source_code, "b === null")]);
+
+        // Undo
+        let ranges = get_changed_ranges(&mut parser, &mut tree, &mut source_code, inverse_edit1);
+        assert_eq!(ranges, vec![range_of(&source_code, "null")]);
+    }
+}
+
+fn index_of(text: &Vec<u8>, substring: &str) -> usize {
+    str::from_utf8(text.as_slice())
+        .unwrap()
+        .find(substring)
+        .unwrap()
+}
+
+fn range_of(text: &Vec<u8>, substring: &str) -> Range {
+    let start_byte = index_of(text, substring);
+    let end_byte = start_byte + substring.as_bytes().len();
+    Range {
+        start_byte,
+        end_byte,
+        start_point: Point::new(0, start_byte),
+        end_point: Point::new(0, end_byte),
+    }
+}
+
+fn get_changed_ranges(
+    parser: &mut Parser,
+    tree: &mut Tree,
+    source_code: &mut Vec<u8>,
+    edit: Edit,
+) -> Vec<Range> {
+    perform_edit(tree, source_code, &edit);
+    let new_tree = parser
+        .parse_utf8(&mut |i, _| &source_code[i..], Some(tree))
+        .unwrap();
+    let result = tree.changed_ranges(&new_tree);
+    *tree = new_tree;
+    result
 }