test_fixtures: Add logic for removing stale test directories.

Similarly to how stale database removal is handled, we add a check for
stale test run directories at the end of the `test-backend` script.

tools/test-backend

@@ -193,7 +193,8 @@ def main() -> None:
     os.environ["http_proxy"] = ""
     os.environ["https_proxy"] = ""
 
-    from zerver.lib.test_fixtures import update_test_databases_if_required
+    from zerver.lib.test_fixtures import update_test_databases_if_required, \
+        remove_test_run_directories
 
     from tools.lib.test_script import (
         assert_provisioning_status_ok,
@@ -461,6 +462,10 @@ def main() -> None:
     #
     # destroy_leaked_test_databases()
 
+    removed = remove_test_run_directories()
+    if removed:
+        print("Removed %s stale test run directories!" % (removed,))
+
     # We'll have printed whether tests passed or failed above
     sys.exit(bool(failures))
 

zerver/lib/test_fixtures.py

@@ -10,6 +10,7 @@ from importlib import import_module
 from io import StringIO
 import glob
 import time
+import shutil
 
 from django.db import connections, DEFAULT_DB_ALIAS, ProgrammingError, \
     connection
@@ -296,3 +297,15 @@ def destroy_leaked_test_databases(expiry_time: int = 60 * 60) -> int:
     if p.returncode != 0:
         raise RuntimeError("Error cleaning up test databases!")
     return len(databases_to_drop)
+
+def remove_test_run_directories(expiry_time: int = 60 * 60) -> int:
+    removed = 0
+    directories = glob.glob(os.path.join(UUID_VAR_DIR, "test-backend", "run_*"))
+    for test_run in directories:
+        if round(time.time()) - os.path.getmtime(test_run) > expiry_time:
+            try:
+                shutil.rmtree(test_run)
+                removed += 1
+            except FileNotFoundError:
+                pass
+    return removed