diff --git a/tests/test_ner.py b/tests/test_ner.py
index f3360a788..1523e02d8 100644
--- a/tests/test_ner.py
+++ b/tests/test_ner.py
@@ -32,7 +32,127 @@ def test_begin(state, sentence):
     assert state.n_ents == 0
     assert state.i == 0
     state.transition('B-PER')
-    assert state.n_ents == 1
+    assert state.n_ents == 0
     assert state.i == 1
     assert state.open_entity
     assert state.ent == {'start': 0, 'label': 3, 'end': 0}
+    assert state.is_valid('I-PER')
+    assert not state.is_valid('I-LOC')
+    assert state.is_valid('L-PER')
+    assert not state.is_valid('L-LOC')
+    assert not state.is_valid('O')
+    assert not state.is_valid('U-PER')
+
+def test_in(state, sentence):
+    state.transition('B-PER')
+    assert state.n_ents == 0
+    state.transition('I-PER')
+    assert state.n_ents == 0
+    assert state.i == 2
+    assert state.is_valid('I-PER')
+    assert state.is_valid('L-PER')
+    assert not state.is_valid('B-PER')
+    assert not state.is_valid('I-LOC')
+    assert not state.is_valid('L-LOC')
+    assert not state.is_valid('U-PER')
+    assert not state.is_valid('O')
+
+
+def test_last(state, sentence):
+    state.transition('B-PER')
+    assert state.n_ents == 0
+    state.transition('L-PER')
+    assert state.n_ents == 1
+    assert state.i == 2
+    assert not state.open_entity
+    assert state.is_valid('B-PER')
+    assert state.is_valid('B-LOC')
+    assert state.is_valid('U-PER')
+    assert state.is_valid('U-LOC')
+    assert state.is_valid('O')
+    assert not state.is_valid('L-PER')
+    assert not state.is_valid('I-PER')
+
+
+def test_unit(state, sentence):
+    assert state.n_ents == 0
+    state.transition('U-PER')
+    assert state.n_ents == 1
+    assert state.i == 1
+    assert not state.open_entity
+    assert state.is_valid('B-PER')
+    assert state.is_valid('B-LOC')
+    assert state.is_valid('U-PER')
+    assert state.is_valid('U-LOC')
+    assert state.is_valid('O')
+    assert not state.is_valid('I-PER')
+    assert not state.is_valid('L-PER')
+
+
+def test_out(state, sentence):
+    assert state.n_ents == 0
+    state.transition('U-PER')
+    assert state.n_ents == 1
+    assert state.i == 1
+    state.transition('O')
+    assert state.i == 2
+    assert not state.open_entity
+    assert state.is_valid('B-PER')
+    assert state.is_valid('B-LOC')
+    assert state.is_valid('U-PER')
+    assert state.is_valid('U-LOC')
+    assert state.is_valid('O')
+    assert not state.is_valid('I-PER')
+    assert not state.is_valid('L-PER')
+
+
+@pytest.fixture
+def golds(sentence):
+    g = ['B-PER', 'L-PER', 'O', 'U-PER', 'O']
+    assert len(g) == len(sentence)
+    return g
+
+
+def test_oracle_gold(state, sentence, golds):
+    state.set_golds(golds)
+    assert state.is_gold('B-PER')
+    assert not state.is_gold('B-LOC')
+    assert not state.is_gold('I-PER')
+    assert not state.is_gold('L-PER')
+    assert not state.is_gold('U-PER')
+    assert not state.is_gold('O')
+    state.transition('B-PER')
+    assert state.is_gold('L-PER')
+    state.transition('L-PER')
+    assert state.is_gold('O')
+    assert not state.is_gold('B-PER')
+    state.transition('O')
+    assert not state.is_gold('B-PER')
+    assert not state.is_gold('O')
+    assert state.is_gold('U-PER')
+    state.transition('U-PER')
+    assert state.is_gold('O')
+    state.transition('O')
+    assert state.i == len(sentence)
+
+
+def test_oracle_miss_entity(state, sentence, golds):
+    state.set_golds(golds)
+    state.transition('O')
+    assert not state.is_gold('L-PER')
+    assert not state.is_gold('U-PER')
+    assert not state.is_gold('I-PER')
+    assert not state.is_gold('B-PER')
+    assert state.is_gold('O')
+    state.transition('O')
+    state.transition('O')
+    assert state.is_gold('U-PER')
+
+
+def test_oracle_extend_entity(state, sentence, golds):
+    state.set_golds(golds)
+    state.transition('B-PER')
+    assert not state.is_gold('I-PER')
+    state.transition('I-PER')
+    assert state.is_gold('L-PER')
+    assert not state.is_gold('I-PER')