Made TestHarness a context manager to ensure files get closed.

mesonbuild/mtest.py

@@ -641,10 +641,21 @@ class TestHarness:
         self.suites = list(ss)
 
     def __del__(self) -> None:
+        self.close_logfiles()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback) -> None:
+        self.close_logfiles()
+
+    def close_logfiles(self) -> None:
         if self.logfile:
             self.logfile.close()
+            self.logfile = None
         if self.jsonlogfile:
             self.jsonlogfile.close()
+            self.jsonlogfile = None
 
     def merge_suite_options(self, options: argparse.Namespace, test: 'TestSerialisation') -> typing.Dict[str, str]:
         if ':' in options.setup:
@@ -1012,8 +1023,8 @@ def run(options: argparse.Namespace) -> int:
         if not rebuild_all(options.wd):
             return 1
 
+    with TestHarness(options) as th:
         try:
-        th = TestHarness(options)
             if options.list:
                 return list_tests(th)
             if not options.args: