def mock_credentials_file(geocaching: Geocaching,
contents: Union[bytes, dict, list, str]):
"""Create a temporary credentials file with given contents and mock a Geocaching instance to use it."""
backup = geocaching._credentials_file
f = NamedTemporaryFile(delete=False)
try:
# bytes are written as-is, others are encoded to JSON
if type(contents) is bytes:
f.write(contents)
else:
f.write(json.dumps(contents).encode("utf-8"))
f.flush()
f.close()
geocaching._credentials_file = f.name
yield
finally:
os.remove(f.name)
geocaching._credentials_file = backup
