use nanmean for loss aggregation (CP fix) (#3033)

* use nanmena for loss aggregation (CP fix)

* use regular asserts

* small changes to make tests isolate

* combining evaluation_loop patches

* fix

* delete unused

* fix check

tests/monkeypatch/test_trainer_loss_calc.py

@@ -0,0 +1,28 @@
+"""Unit tests for trainer loss calc monkeypatch."""
+
+import unittest
+
+from axolotl.monkeypatch.transformers.trainer_loss_calc import (
+    check_evaluation_loop_is_fsdp2_patchable,
+    check_evaluation_loop_is_patchable,
+    check_maybe_log_save_evaluate_is_patchable,
+)
+
+
+class TestTrainerLossCalc(unittest.TestCase):
+    """
+    Unit test class for trainer loss calc monkeypatch
+    """
+
+    def test_trainer_loss_calc_is_patchable(self):
+        """
+        Test that the upstream transformers code is still patchable. This will fail if
+        the patched code changes upstream.
+        """
+        assert check_evaluation_loop_is_patchable()
+        assert check_evaluation_loop_is_fsdp2_patchable()
+        assert check_maybe_log_save_evaluate_is_patchable()
+
+
+if __name__ == "__main__":
+    unittest.main()