Tests: refactor cleanup (#1744)

* wip

* cleaning

* optim imports

* -

* default hparams

* fix restore

* fix imports

tests/base/model_valid_dataloaders.py

@@ -0,0 +1,20 @@
+from abc import ABC, abstractmethod
+
+from tests.base.dataloaders import CustomInfDataloader
+
+
+class ValDataloaderVariations(ABC):
+
+    @abstractmethod
+    def dataloader(self, train: bool):
+        """placeholder"""
+
+    def val_dataloader(self):
+        return self.dataloader(train=False)
+
+    def val_dataloader__multiple(self):
+        return [self.dataloader(train=False),
+                self.dataloader(train=False)]
+
+    def val_dataloader__infinite(self):
+        return CustomInfDataloader(self.dataloader(train=False))