Test overwrite options.use_or_syntax

Author: cdce8p

mypy/test/helpers.py

@@ -358,6 +358,7 @@ def parse_options(
         options.error_summary = False
         options.hide_error_codes = True
         options.force_union_syntax = True
+        options.use_or_syntax = lambda: True
 
     # Allow custom python version to override testfile_pyversion.
     if all(flag.split("=")[0] != "--python-version" for flag in flag_list):