bah, win32 and its exclusive opens

Author: ikonst

mypy/test/testupdatedata.py

@@ -2,8 +2,7 @@
 import subprocess
 import sys
 import textwrap
-from os.path import basename
-from tempfile import NamedTemporaryFile
+from pathlib import Path
 
 from mypy.test.config import test_data_prefix
 from mypy.test.helpers import Suite
@@ -13,14 +12,14 @@ class UpdateDataSuite(Suite):
     def _run_pytest_update_data(self, data_suite: str, *, max_attempts: int) -> str:
         """
         Runs a suite of data test cases through 'pytest --update-data' until either tests pass
-        or until a maximum number of attempts. (Multiple attempts can be needed for incremental tests.)
+        or until a maximum number of attempts (needed for incremental tests).
         """
-        with NamedTemporaryFile(
-            mode="w+", dir=test_data_prefix, prefix="check-update-data-", suffix=".test"
-        ) as tmp_file:
-            tmp_file.write(textwrap.dedent(data_suite).lstrip())
-            tmp_file.flush()
-            test_nodeid = f"mypy/test/testcheck.py::TypeCheckSuite::{basename(tmp_file.name)}"
+        p = Path(test_data_prefix) / "check-update-data.test"
+        assert not p.exists()
+        try:
+            p.write_text(textwrap.dedent(data_suite).lstrip())
+
+            test_nodeid = f"mypy/test/testcheck.py::TypeCheckSuite::{p.name}"
             args = [sys.executable, "-m", "pytest", "-n", "0", "-s", "--update-data", test_nodeid]
             if sys.version_info >= (3, 8):
                 cmd = shlex.join(args)
@@ -31,8 +30,10 @@ def _run_pytest_update_data(self, data_suite: str, *, max_attempts: int) -> str:
                 if res.returncode == 0:
                     break
                 print(f"`{cmd}` returned {res.returncode}: {i} attempts remaining")
-            tmp_file.seek(0)
-            return tmp_file.read()
+
+            return p.read_text()
+        finally:
+            p.unlink()
 
     def test_update_data(self) -> None:
         # Note: We test multiple testcases rather than 'test case per test case'