Add undiff tests

reconcile-js/package-lock.json

@@ -1231,13 +1231,13 @@
       "license": "MIT"
     },
     "node_modules/@types/node": {
-      "version": "24.0.10",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-24.0.10.tgz",
-      "integrity": "sha512-ENHwaH+JIRTDIEEbDK6QSQntAYGtbvdDXnMXnZaZ6k13Du1dPMmprkEHIL7ok2Wl2aZevetwTAb5S+7yIF+enA==",
+      "version": "24.10.1",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-24.10.1.tgz",
+      "integrity": "sha512-GNWcUTRBgIRJD5zj+Tq0fKOJ5XZajIiBroOF0yvj2bSU1WvNdYS/dn9UxwsujGW4JX06dnHyjV2y9rRaybH0iQ==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
-        "undici-types": "~7.8.0"
+        "undici-types": "~7.16.0"
       }
     },
     "node_modules/@types/stack-utils": {
@@ -5274,9 +5274,9 @@
       }
     },
     "node_modules/undici-types": {
-      "version": "7.8.0",
-      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.8.0.tgz",
-      "integrity": "sha512-9UJ2xGDvQ43tYyVMpuHlsgApydB8ZKfVYTsLDhXkFL/6gfkp+U8xTGdh8pMJv1SpZna0zxG1DwsKZsreLbXBxw==",
+      "version": "7.16.0",
+      "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-7.16.0.tgz",
+      "integrity": "sha512-Zz+aZWSj8LE6zoxD+xrjh4VfkIG8Ya6LvYkZqtUQGJPZjYl53ypCaUwWqo7eI0x66KBGeRo+mlBEkMSeSZ38Nw==",
       "dev": true,
       "license": "MIT"
     },

reconcile-js/src/index.test.ts

@@ -1,4 +1,9 @@
-import { reconcile, reconcileWithHistory } from './index';
+import { reconcile, reconcileWithHistory, diff, undiff } from './index';
+import * as fs from 'fs';
+import * as path from 'path';
+import { fileURLToPath } from 'url';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
 describe('reconcile', () => {
   it('call reconcile without cursors', () => {
@@ -44,3 +49,35 @@ describe('reconcile', () => {
     expect(result.history.length).toBeGreaterThan(0);
   });
 });
+
+describe('test_merge_files_without_panic', () => {
+  const resourcesPath = path.join(__dirname, '../../tests/resources');
+
+  const readFileSlice = (fileName: string, start: number, end: number): string => {
+    const filePath = path.join(resourcesPath, fileName);
+    const content = fs.readFileSync(filePath, 'utf-8');
+    const chars = Array.from(content); // Handle unicode properly
+    return chars.slice(start, Math.min(end, chars.length)).join('');
+  };
+
+  const files = ['pride_and_prejudice.txt', 'room_with_a_view.txt', 'blns.txt'];
+
+  const ranges = [{ start: 0, end: 50000 }];
+
+  files.forEach((file1) => {
+    files.forEach((file2) => {
+      ranges.forEach((range1) => {
+        ranges.forEach((range2) => {
+          it(`should diff & undiff ${file1}[${range1.start}..${range1.end}], ${file2}[${range2.start}..${range2.end}] without panic`, () => {
+            const content1 = readFileSlice(file1, range1.start, range1.end);
+            const content2 = readFileSlice(file2, range2.start, range2.end);
+
+            const changes = diff(content1, content2);
+            const actual = undiff(content1, changes);
+            expect(actual).toEqual(content2);
+          });
+        });
+      });
+    });
+  });
+});

reconcile-js/tsconfig.json

@@ -8,7 +8,6 @@
     "declaration": true,
     "declarationDir": "./dist/types",
     "skipLibCheck": true,
-    "inlineSourceMap": true
+    "inlineSourceMap": true,
   },
-  "exclude": ["./dist", "**/*.test.ts"]
 }