test: additional integration tests for editing a file (#9963)

Co-authored-by: Taneja Hriday <hridayt@google.com>

integration-tests/replace.test.ts

@@ -91,4 +91,98 @@ describe('replace', () => {
     const newFileContent = rig.readFile(fileName);
     expect(newFileContent).toBe(expectedContent);
   });
+
+  it('should fail safely when old_string is not found', async () => {
+    const rig = new TestRig();
+    await rig.setup('should fail safely when old_string is not found');
+    const fileName = 'no_match.txt';
+    const fileContent = 'hello world';
+    rig.createFile(fileName, fileContent);
+
+    const prompt = `replace "goodbye" with "farewell" in ${fileName}`;
+    await rig.run(prompt);
+
+    await rig.waitForTelemetryReady();
+    const toolLogs = rig.readToolLogs();
+
+    const replaceAttempt = toolLogs.find(
+      (log) => log.toolRequest.name === 'replace',
+    );
+    const readAttempt = toolLogs.find(
+      (log) => log.toolRequest.name === 'read_file',
+    );
+
+    // VERIFY: The model must have at least tried to read the file or perform a replace.
+    expect(
+      readAttempt || replaceAttempt,
+      'Expected model to attempt a read_file or replace',
+    ).toBeDefined();
+
+    // If the model tried to replace, that specific attempt must have failed.
+    if (replaceAttempt) {
+      if (replaceAttempt.toolRequest.success) {
+        console.error(
+          'The replace tool succeeded when it was expected to fail',
+        );
+        console.error('Tool call args:', replaceAttempt.toolRequest.args);
+      }
+      expect(
+        replaceAttempt.toolRequest.success,
+        'If replace is called, it must fail',
+      ).toBe(false);
+    }
+
+    // CRITICAL: The final content of the file must be unchanged.
+    const newFileContent = rig.readFile(fileName);
+    expect(newFileContent).toBe(fileContent);
+  });
+
+  it('should insert a multi-line block of text', async () => {
+    const rig = new TestRig();
+    await rig.setup('should insert a multi-line block of text');
+    const fileName = 'insert_block.js';
+    const originalContent = 'function hello() {\n  // INSERT_CODE_HERE\n}';
+    const newBlock = "console.log('hello');\n  console.log('world');";
+    const expectedContent = `function hello() {\n  ${newBlock}\n}`;
+    rig.createFile(fileName, originalContent);
+
+    const prompt = `In ${fileName}, replace "// INSERT_CODE_HERE" with:\n${newBlock}`;
+    const result = await rig.run(prompt);
+
+    const foundToolCall = await rig.waitForToolCall('replace');
+    if (!foundToolCall) {
+      printDebugInfo(rig, result);
+    }
+    expect(foundToolCall, 'Expected to find a replace tool call').toBeTruthy();
+
+    const newFileContent = rig.readFile(fileName);
+
+    expect(newFileContent.replace(/\r\n/g, '\n')).toBe(
+      expectedContent.replace(/\r\n/g, '\n'),
+    );
+  });
+
+  it('should delete a block of text', async () => {
+    const rig = new TestRig();
+    await rig.setup('should delete a block of text');
+    const fileName = 'delete_block.txt';
+    const blockToDelete =
+      '## DELETE THIS ##\nThis is a block of text to delete.\n## END DELETE ##';
+    const originalContent = `Hello\n${blockToDelete}\nWorld`;
+    const expectedContent = 'Hello\nWorld';
+    rig.createFile(fileName, originalContent);
+
+    const prompt = `In ${fileName}, delete the entire block from "## DELETE THIS ##" to "## END DELETE ##" including the markers.`;
+    const result = await rig.run(prompt);
+
+    const foundToolCall = await rig.waitForToolCall('replace');
+    if (!foundToolCall) {
+      printDebugInfo(rig, result);
+    }
+    expect(foundToolCall, 'Expected to find a replace tool call').toBeTruthy();
+
+    const newFileContent = rig.readFile(fileName);
+
+    expect(newFileContent).toBe(expectedContent);
+  });
 });