test: cover resuming engine with unknown epoch length

Author: nightcityblade

tests/ignite/engine/test_engine.py

@@ -1,3 +1,4 @@
+import itertools
 import math
 import os
 import time
@@ -132,6 +133,23 @@ def end_of_epoch_handler(engine):
         assert engine.should_terminate
         assert engine._dataloader_iter is None
 
+    def test_continue_after_terminate_with_unknown_epoch_length(self):
+        def _run_iteration(engine, batch):
+            if batch > 2:
+                engine.terminate()
+
+        engine = Engine(_run_iteration)
+
+        state = engine.run(itertools.count(start=0), max_epochs=engine.state.epoch + 1)
+        assert state.epoch == 1
+        assert state.iteration == 4
+        assert state.epoch_length is None
+
+        state = engine.run(itertools.count(start=0), max_epochs=engine.state.epoch + 1)
+        assert state.epoch == 2
+        assert state.iteration == 8
+        assert state.epoch_length is None
+
     @pytest.mark.parametrize("data, epoch_length", [(None, 10), (range(10), None)])
     def test_terminate_at_start_of_epoch(self, data, epoch_length):
         max_epochs = 5