diff --git a/tests/test_fix_eval_warnings.py b/tests/test_fix_eval_warnings.py
index 969fe6c..222b801 100644
--- a/tests/test_fix_eval_warnings.py
+++ b/tests/test_fix_eval_warnings.py
@@ -1,37 +1,42 @@
-"""Tests for fix_eval_warnings."""
+"""test_fix_eval_warnings."""
+
+from __future__ import annotations
 
 from pathlib import Path
-from unittest.mock import MagicMock, patch
+from typing import TYPE_CHECKING
 
-import pytest
 from typer.testing import CliRunner
 
 from python.tools.fix_eval_warnings import Config, app, generate_fix, parse_warnings
 from tests.conftest import TOKEN
 
+if TYPE_CHECKING:
+    from pyfakefs.fake_filesystem import FakeFilesystem
+    from pytest_mock import MockerFixture
+
 runner = CliRunner()
 
 
-@pytest.fixture
-def log_file(tmp_path: Path) -> Path:
-    """Create a dummy log file."""
-    log_path = tmp_path / "build.log"
-    log_path.write_text("Some output\nevaluation warning: 'system' is deprecated\nMore output", encoding="utf-8")
-    return log_path
-
-
-def test_parse_warnings(log_file: Path) -> None:
-    """Test parsing warnings from a log file."""
+def test_parse_warnings(fs: FakeFilesystem) -> None:
+    """test_parse_warnings."""
+    log_file = Path("/build.log")
+    fs.create_file(
+        log_file,
+        contents="Some output\nevaluation warning: 'system' is deprecated\nMore output",
+        encoding="utf-8",
+    )
     warnings = parse_warnings(log_file)
     assert len(warnings) == 1
     assert warnings[0] == "evaluation warning: 'system' is deprecated"
 
 
-@patch("python.tools.fix_eval_warnings.requests.post")
-def test_generate_fix(mock_post: MagicMock) -> None:
-    """Test generating a fix."""
-    mock_response = MagicMock()
-    mock_response.json.return_value = {"choices": [{"message": {"content": "Use stdenv.hostPlatform.system"}}]}
+def test_generate_fix(mocker: MockerFixture) -> None:
+    """test_generate_fix."""
+    mock_post = mocker.patch("python.tools.fix_eval_warnings.requests.post")
+    mock_response = mocker.MagicMock()
+    mock_response.json.return_value = {
+        "choices": [{"message": {"content": "Use stdenv.hostPlatform.system"}}]
+    }
     mock_post.return_value = mock_response
 
     config = Config(github_token=TOKEN)
@@ -41,20 +46,30 @@ def test_generate_fix(mock_post: MagicMock) -> None:
     mock_post.assert_called_once()
 
 
-@patch("python.tools.fix_eval_warnings.logger")
-@patch("python.tools.fix_eval_warnings.generate_fix")
-def test_main(mock_generate_fix: MagicMock, mock_logger: MagicMock, log_file: Path) -> None:
-    """Test the main CLI."""
+def test_main(mocker: MockerFixture, fs: FakeFilesystem) -> None:
+    """test_main."""
+    log_file = Path("/build.log")
+    fs.create_file(
+        log_file,
+        contents="Some output\nevaluation warning: 'system' is deprecated\nMore output",
+        encoding="utf-8",
+    )
+
+    mock_generate_fix = mocker.patch("python.tools.fix_eval_warnings.generate_fix")
     mock_generate_fix.return_value = "Fixed it"
+    mock_logger = mocker.patch("python.tools.fix_eval_warnings.logger")
 
     # We need to mock GITHUB_TOKEN env var or the script will warn/fail
-    with patch.dict("os.environ", {"GITHUB_TOKEN": TOKEN}):
-        result = runner.invoke(app, [str(log_file)])
+    mocker.patch.dict("os.environ", {"GITHUB_TOKEN": TOKEN})
+
+    result = runner.invoke(app, [str(log_file)])
 
     assert result.exit_code == 0
     # Verify logger calls instead of stdout, as CliRunner might not capture logging output correctly
     # when logging is configured to write to sys.stdout directly.
     assert any("Found 1 warnings" in str(call) for call in mock_logger.info.call_args_list)
-    assert any("Fix suggestions written to fix_suggestions.md" in str(call) for call in mock_logger.info.call_args_list)
+    assert any(
+        "Fix suggestions written to fix_suggestions.md" in str(call)
+        for call in mock_logger.info.call_args_list
+    )
     assert Path("fix_suggestions.md").exists()
-    Path("fix_suggestions.md").unlink()