⚡🩹 Fix lightning training without validation

src/pykeen/contrib/lightning.py

@@ -157,6 +157,8 @@ def train_dataloader(self):
     def val_dataloader(self):
         """Create the validation data loader."""
         # TODO: In sLCWA, we still want to calculate validation *metrics* in LCWA
+        if self.dataset.validation is None:
+            return []
         return self._dataloader(triples_factory=self.dataset.validation, shuffle=False)
 
     def configure_optimizers(self):

src/pykeen/stoppers/stopper.py

@@ -48,7 +48,7 @@ def get_summary_dict(self) -> Mapping[str, Any]:
         """Get a summary dict."""
         raise NotImplementedError
 
-    def _write_from_summary_dict(
+    def _write_from_summary_dict(  # noqa: B027
         self,
         *,
         frequency: int,

tests/test_lightning.py

@@ -11,7 +11,7 @@
 except ImportError:
     LIT_MODULES = []
 from pykeen import models
-from pykeen.datasets import get_dataset
+from pykeen.datasets import EagerDataset, get_dataset
 from pykeen.typing import TRAINING
 
 EMBEDDING_DIM = 8
@@ -103,3 +103,29 @@ def test_lit_training(model, model_kwargs, training_loop):
             max_epochs=2,
         ),
     )
+
+
+def test_lit_pipeline_with_dataset_without_validation():
+    """Test training on a dataset without validation triples."""
+    from pykeen.contrib.lightning import lit_pipeline
+
+    dataset = get_dataset(dataset="nations")
+    dataset = EagerDataset(training=dataset.training, testing=dataset.testing, metadata=dataset.metadata)
+
+    lit_pipeline(
+        training_loop="slcwa",
+        training_loop_kwargs=dict(
+            model="transe",
+            dataset=dataset,
+        ),
+        trainer_kwargs=dict(
+            # automatically choose accelerator
+            accelerator="auto",
+            # defaults to TensorBoard; explicitly disabled here
+            logger=False,
+            # disable checkpointing
+            enable_checkpointing=False,
+            # fast run
+            max_epochs=2,
+        ),
+    )