def on_test_batch_start(
        self,
        trainer: "pl.Trainer",
        pl_module: "pl.LightningModule",
        batch: Any,
        batch_idx: int,
        dataloader_idx: int = 0,
    ) -> None:
        """Called when the test batch begins."""
Called when the test batch begins.
src/lightning/pytorch/callbacks/callback.py