fix: update EditFileTool to handle cross-platform line breaks and escape regex characters

Change-Id: Id155218fa6feb7e004684d8f96cd0598fa4d2766

Author: wyf7107

src/google/adk/tools/environment/_tools.py

@@ -17,6 +17,7 @@
 from __future__ import annotations
 
 import logging
+import re
 from typing import Any
 from typing import Optional
 from typing import TYPE_CHECKING
@@ -381,7 +382,13 @@ async def run_async(
     except FileNotFoundError:
       return {'status': 'error', 'error': f'File not found: {path}'}
 
-    count = content.count(old_string)
+    # Normalize line breaks in old_string to \n and use regex for flexible matching
+    normalized_old = old_string.replace('\r\n', '\n')
+    pattern = re.escape(normalized_old).replace('\n', '\r?\n')
+
+    matches = re.findall(pattern, content)
+    count = len(matches)
+
     if count == 0:
       return {
           'status': 'error',
@@ -399,6 +406,6 @@ async def run_async(
           ),
       }
 
-    new_content = content.replace(old_string, new_string, 1)
+    new_content = re.sub(pattern, lambda m: new_string, content, count=1)
     await self._environment.write_file(path, new_content)
     return {'status': 'ok', 'message': f'Edited {path}'}

tests/unittests/tools/environment/test_tools_edit_file.py

@@ -0,0 +1,150 @@
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Tests for EditFileTool.
+
+Verifies that EditFileTool correctly handles line break differences.
+"""
+
+from pathlib import Path
+
+from google.adk.environment._local_environment import LocalEnvironment
+from google.adk.tools.environment._tools import EditFileTool
+import pytest
+import pytest_asyncio
+
+
+@pytest_asyncio.fixture(name="env")
+async def _env(tmp_path: Path):
+  """Create and initialize a LocalEnvironment backed by a temp directory."""
+  environment = LocalEnvironment(working_dir=tmp_path)
+  await environment.initialize()
+  yield environment
+  await environment.close()
+
+
+class TestEditFileTool:
+  """Tests for EditFileTool behavior."""
+
+  @pytest.mark.asyncio
+  async def test_edit_file_handles_line_breaks_linux_file_windows_search(
+      self, env: LocalEnvironment
+  ):
+    """File has \\n, search string has \\r\\n."""
+    # Arrange
+    tool = EditFileTool(env)
+    await env.write_file("test.txt", "line1\nline2\nline3")
+
+    args = {
+        "path": "test.txt",
+        "old_string": "line1\r\nline2",
+        "new_string": "line1_replaced\nline2_replaced",
+    }
+
+    # Act
+    result = await tool.run_async(args=args, tool_context=None)
+
+    # Assert
+    assert result["status"] == "ok"
+    data = await env.read_file("test.txt")
+    assert data == b"line1_replaced\nline2_replaced\nline3"
+
+  @pytest.mark.asyncio
+  async def test_edit_file_handles_line_breaks_windows_file_linux_search(
+      self, env: LocalEnvironment
+  ):
+    """File has \\r\\n, search string has \\n."""
+    # Arrange
+    tool = EditFileTool(env)
+    await env.write_file("test.txt", "line1\r\nline2\r\nline3")
+
+    args = {
+        "path": "test.txt",
+        "old_string": "line1\nline2",
+        "new_string": "line1_replaced\r\nline2_replaced",
+    }
+
+    # Act
+    result = await tool.run_async(args=args, tool_context=None)
+
+    # Assert
+    assert result["status"] == "ok"
+    data = await env.read_file("test.txt")
+    assert data == b"line1_replaced\r\nline2_replaced\r\nline3"
+
+  @pytest.mark.asyncio
+  async def test_edit_file_fails_on_multiple_matches(
+      self, env: LocalEnvironment
+  ):
+    """Tool fails if old_string appears multiple times."""
+    # Arrange
+    tool = EditFileTool(env)
+    await env.write_file("test.txt", "line1\nline2\nline1\nline2")
+
+    args = {
+        "path": "test.txt",
+        "old_string": "line1\nline2",
+        "new_string": "replaced",
+    }
+
+    # Act
+    result = await tool.run_async(args=args, tool_context=None)
+
+    # Assert
+    assert result["status"] == "error"
+    assert "appears 2 times" in result["error"]
+
+  @pytest.mark.asyncio
+  async def test_edit_file_exact_match_works(self, env: LocalEnvironment):
+    """Exact match works as before."""
+    # Arrange
+    tool = EditFileTool(env)
+    await env.write_file("test.txt", "line1\nline2\nline3")
+
+    args = {
+        "path": "test.txt",
+        "old_string": "line1\nline2",
+        "new_string": "replaced",
+    }
+
+    # Act
+    result = await tool.run_async(args=args, tool_context=None)
+
+    # Assert
+    assert result["status"] == "ok"
+    data = await env.read_file("test.txt")
+    assert data == b"replaced\nline3"
+
+  @pytest.mark.asyncio
+  async def test_edit_file_handles_special_regex_chars(
+      self, env: LocalEnvironment
+  ):
+    """Special regex characters in old_string are escaped."""
+    # Arrange
+    tool = EditFileTool(env)
+    await env.write_file("test.txt", "line1.content\nline2")
+
+    args = {
+        "path": "test.txt",
+        "old_string": "line1.content",
+        "new_string": "replaced",
+    }
+
+    # Act
+    result = await tool.run_async(args=args, tool_context=None)
+
+    # Assert
+    assert result["status"] == "ok"
+    data = await env.read_file("test.txt")
+    assert data == b"replaced\nline2"