test: chmod only container-owned files in coverage_command

Author: davidsmejia

bin/lib/test/_shared.py

@@ -6,13 +6,15 @@
 def coverage_command(extra_args):
     """Bash one-liner: run manage.py under coverage, write XML, print report, preserve test exit code."""
     args_str = " ".join(shlex.quote(a) for a in extra_args)
-    # chmod opens up the bind-mount output so the host (CI runner, dev user)
-    # can read coverage.xml regardless of which UID the container runs as.
+    # Open up the bind-mount output so the host (CI runner, dev user) can read
+    # coverage.xml regardless of which UID the container runs as. Filter to
+    # files owned by the current UID — pre-existing committed fixtures belong
+    # to the host user and chmod requires ownership, not just write bits.
     return (
         f'coverage run --source="." manage.py test --settings=tests.settings --no-input {args_str}; '
         "exit_code=$?; "
         "coverage xml -o data_store/coverage.xml; "
-        "chmod -R a+rw data_store; "
+        'find data_store -user "$(id -u)" -exec chmod a+rw {} +; '
         "coverage report -m; "
         "exit $exit_code"
     )