fix randomly failing test execution on Windows

shutil.rmtree, which is used by tempfile.TemporaryDirectory, randomly fails
on Windows, because the directory is not empty although it should be,
because all files were deleted by shutil.rmtree internals before trying to
remove the directory.
A simple retry approach fixes the issue.

run_tests.py

@@ -42,6 +42,25 @@ class TestResult:
         self.buildtime = buildtime
         self.testtime = testtime
 
+class AutoDeletedDir():
+    def __init__(self, dir):
+        self.dir = dir
+    def __enter__(self):
+        os.makedirs(self.dir, exist_ok=True)
+        return self.dir
+    def __exit__(self, type, value, traceback):
+        # On Windows, shutil.rmtree fails sometimes, because 'the directory is not empty'.
+        # Retrying fixes this.
+        # That's why we don't use tempfile.TemporaryDirectory, but wrap the deletion in the AutoDeletedDir class.
+        retries = 5
+        for i in range(0, retries):
+            try:
+                shutil.rmtree(self.dir)
+                return
+            except OSError:
+                if i == retries:
+                    raise
+
 passing_tests = 0
 failing_tests = 0
 skipped_tests = 0
@@ -200,8 +219,8 @@ def parse_test_args(testdir):
 def run_test(skipped, testdir, extra_args, flags, compile_commands, install_commands, should_succeed):
     if skipped:
         return None
-    with tempfile.TemporaryDirectory(prefix='b ', dir='.') as build_dir:
-        with tempfile.TemporaryDirectory(prefix='i ', dir=os.getcwd()) as install_dir:
+    with AutoDeletedDir(tempfile.mkdtemp(prefix='b ', dir='.')) as build_dir:
+        with AutoDeletedDir(tempfile.mkdtemp(prefix='i ', dir=os.getcwd())) as install_dir:
             try:
                 return _run_test(testdir, build_dir, install_dir, extra_args, flags, compile_commands, install_commands, should_succeed)
             finally: