🎯 PR: Improve Edit Tool Reliability with Fuzzy Matching Pipeline (#1025)

packages/core/src/utils/editHelper.test.ts

@@ -0,0 +1,153 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, expect, it } from 'vitest';
+import {
+  countOccurrences,
+  maybeAugmentOldStringForDeletion,
+  normalizeEditStrings,
+} from './editHelper.js';
+
+describe('normalizeEditStrings', () => {
+  const file = `const one = 1;
+const two = 2;
+`;
+
+  it('returns literal matches unchanged and trims new_string trailing whitespace', () => {
+    const result = normalizeEditStrings(
+      file,
+      'const two = 2;',
+      '  const two = 42;  ',
+    );
+    expect(result).toEqual({
+      oldString: 'const two = 2;',
+      newString: '  const two = 42;',
+    });
+  });
+
+  it('normalizes smart quotes to match on-disk text', () => {
+    const result = normalizeEditStrings(
+      "const greeting = 'Don't';\n",
+      'const greeting = ‘Don’t’;',
+      'const greeting = “Hello”;   ',
+    );
+    expect(result).toEqual({
+      oldString: "const greeting = 'Don't';",
+      newString: 'const greeting = “Hello”;',
+    });
+  });
+
+  it('falls back to original strings when no match is found', () => {
+    const result = normalizeEditStrings(file, 'missing text', 'replacement');
+    expect(result).toEqual({
+      oldString: 'missing text',
+      newString: 'replacement',
+    });
+  });
+
+  it('still trims new_string when editing a brand-new file', () => {
+    const result = normalizeEditStrings(null, '', 'new file contents   ');
+    expect(result).toEqual({
+      oldString: '',
+      newString: 'new file contents',
+    });
+  });
+
+  it('matches unicode dash variants', () => {
+    const result = normalizeEditStrings(
+      'const range = "1-2";\n',
+      'const range = "1\u20132";',
+      'const range = "3\u20135";   ',
+    );
+    expect(result).toEqual({
+      oldString: 'const range = "1-2";',
+      newString: 'const range = "3\u20135";',
+    });
+  });
+
+  it('matches when trailing whitespace differs only at line ends', () => {
+    const result = normalizeEditStrings(
+      'value = 1;\n',
+      'value = 1;   \n',
+      'value = 2;   \n',
+    );
+    expect(result).toEqual({
+      oldString: 'value = 1;\n',
+      newString: 'value = 2;\n',
+    });
+  });
+
+  it('treats non-breaking spaces as regular spaces', () => {
+    const result = normalizeEditStrings(
+      'const label = "hello world";\n',
+      'const label = "hello\u00a0world";',
+      'const label = "hi\u00a0world";',
+    );
+    expect(result).toEqual({
+      oldString: 'const label = "hello world";',
+      newString: 'const label = "hi\u00a0world";',
+    });
+  });
+
+  it('drops trailing newline from new content when the file lacks it', () => {
+    const result = normalizeEditStrings(
+      'console.log("hi")',
+      'console.log("hi")\n',
+      'console.log("bye")\n',
+    );
+    expect(result).toEqual({
+      oldString: 'console.log("hi")',
+      newString: 'console.log("bye")',
+    });
+  });
+});
+
+describe('countOccurrences', () => {
+  it('returns zero when substring empty or missing', () => {
+    expect(countOccurrences('abc', '')).toBe(0);
+    expect(countOccurrences('abc', 'z')).toBe(0);
+  });
+
+  it('counts non-overlapping occurrences', () => {
+    expect(countOccurrences('aaaa', 'aa')).toBe(2);
+  });
+});
+
+describe('maybeAugmentOldStringForDeletion', () => {
+  const file = 'console.log("hi")\nconsole.log("bye")\n';
+
+  it('appends newline when deleting text followed by newline', () => {
+    expect(
+      maybeAugmentOldStringForDeletion(file, 'console.log("hi")', ''),
+    ).toBe('console.log("hi")\n');
+  });
+
+  it('leaves strings untouched when not deleting', () => {
+    expect(
+      maybeAugmentOldStringForDeletion(
+        file,
+        'console.log("hi")',
+        'replacement',
+      ),
+    ).toBe('console.log("hi")');
+  });
+
+  it('does not append newline when file lacks the variant', () => {
+    expect(
+      maybeAugmentOldStringForDeletion(
+        'console.log("hi")',
+        'console.log("hi")',
+        '',
+      ),
+    ).toBe('console.log("hi")');
+  });
+
+  it('no-ops when the old string already ends with a newline', () => {
+    expect(
+      maybeAugmentOldStringForDeletion(file, 'console.log("bye")\n', ''),
+    ).toBe('console.log("bye")\n');
+  });
+});