From 46f89432417dd68a360524ebb3856ca0b42f5c24 Mon Sep 17 00:00:00 2001
From: Vlady Veselinov <vladkodmc@gmail.com>
Date: Thu, 6 Nov 2025 07:57:18 +0000
Subject: [PATCH 1/2] add node id stability test

---
 .../test/node-id-stability.test.ts            | 68 +++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 lib/binding_web/test/node-id-stability.test.ts

diff --git a/lib/binding_web/test/node-id-stability.test.ts b/lib/binding_web/test/node-id-stability.test.ts
new file mode 100644
index 00000000..f73bc1d1
--- /dev/null
+++ b/lib/binding_web/test/node-id-stability.test.ts
@@ -0,0 +1,68 @@
+import { describe, it, expect, beforeAll, beforeEach, afterEach } from "vitest";
+import { Language, Tree, Edit } from "../src";
+import { Parser } from "../src";
+import helper from "./helper";
+
+describe("node id stability", () => {
+  let parser: Parser;
+  let tree: Tree | null;
+  let JavaScript: Language;
+
+  beforeAll(async () => {
+    ({ JavaScript } = await helper);
+  });
+
+  beforeEach(() => {
+    tree = null;
+    parser = new Parser();
+    parser.setLanguage(JavaScript);
+  });
+
+  afterEach(() => {
+    parser.delete();
+    tree!.delete();
+  });
+
+  it("node ID of existing variable_declarator is stable after inserting second declaration", () => {
+    const source1 = `
+      let name = "John Doe";
+    `;
+    tree = parser.parse(source1);
+
+    const variableDeclaratorsBefore = tree?.rootNode.descendantsOfType(
+      "variable_declarator"
+    );
+    const firstDeclarationIdBefore = variableDeclaratorsBefore?.[0]?.id;
+
+    expect(firstDeclarationIdBefore).toBeTypeOf("number");
+
+    const source2 = `
+      let age = 31;
+    `;
+
+    const startIndex = 0;
+    const startPosition = { row: 0, column: 0 };
+    const newEndPosition = { row: 1, column: 0 };
+
+    const edit = new Edit({
+      startIndex,
+      oldEndIndex: startIndex,
+      newEndIndex: startIndex + source2.length,
+      startPosition,
+      oldEndPosition: startPosition,
+      newEndPosition,
+    });
+
+    tree?.edit(edit);
+
+    const newText = source2 + source1;
+    tree = parser.parse(newText, tree);
+
+    const variableDeclaratorsAfter = tree?.rootNode.descendantsOfType(
+      "variable_declarator"
+    );
+    const nodeIds = variableDeclaratorsAfter?.map((n) => n.id);
+
+    expect(nodeIds).toContain(firstDeclarationIdBefore);
+  });
+});

From 9db5ef325baed90ab1def665f71af9edbf76508b Mon Sep 17 00:00:00 2001
From: Vlady Veselinov <vladkodmc@gmail.com>
Date: Thu, 6 Nov 2025 08:09:36 +0000
Subject: [PATCH 2/2] clean up fixture

---
 lib/binding_web/test/node-id-stability.test.ts | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/lib/binding_web/test/node-id-stability.test.ts b/lib/binding_web/test/node-id-stability.test.ts
index f73bc1d1..389bfc0e 100644
--- a/lib/binding_web/test/node-id-stability.test.ts
+++ b/lib/binding_web/test/node-id-stability.test.ts
@@ -24,9 +24,7 @@ describe("node id stability", () => {
   });
 
   it("node ID of existing variable_declarator is stable after inserting second declaration", () => {
-    const source1 = `
-      let name = "John Doe";
-    `;
+    const source1 = `let name = "John Doe";\n`;
     tree = parser.parse(source1);
 
     const variableDeclaratorsBefore = tree?.rootNode.descendantsOfType(
@@ -36,9 +34,7 @@ describe("node id stability", () => {
 
     expect(firstDeclarationIdBefore).toBeTypeOf("number");
 
-    const source2 = `
-      let age = 31;
-    `;
+    const source2 = `let age = 31;\n`;
 
     const startIndex = 0;
     const startPosition = { row: 0, column: 0 };