add unit test for v2 lrn scheduling bug

https://anki.tenderapp.com/discussions/ankimobile/9714-deleting-custom-study-deck-skips-learning-step-time

tests/test_schedv2.py

@@ -708,14 +708,22 @@ def test_filt_reviewing_early_normal():
 
 def test_filt_keep_lrn_state():
     d = getEmptyCol()
+
     f = d.newNote()
     f['Front'] = "one"
     d.addNote(f)
 
     # fail the card outside filtered deck
     c = d.sched.getCard()
+    d.sched._cardConf(c)['new']['delays'] = [1, 10, 61]
+    d.decks.save()
+
     d.sched.answerCard(c, 1)
 
+    assert c.type == c.queue == 1
+    assert c.left == 3003
+
+    d.sched.answerCard(c, 3)
     assert c.type == c.queue == 1
 
     # create a dynamic deck and refresh it
@@ -726,11 +734,19 @@ def test_filt_keep_lrn_state():
     # card should still be in learning state
     c.load()
     assert c.type == c.queue == 1
+    assert c.left == 2002
+
+    # should be able to advance learning steps
+    d.sched.answerCard(c, 3)
+    # should be due at least an hour in the future
+    assert c.due - intTime() > 60*60
 
     # emptying the deck preserves learning state
     d.sched.emptyDyn(did)
     c.load()
     assert c.type == c.queue == 1
+    assert c.left == 1001
+    assert c.due - intTime() > 60*60
 
 def test_preview():
     # add cards