Add regression test for #3951

spacy/tests/regression/test_issue3951.py

@@ -0,0 +1,22 @@
+# coding: utf8
+from __future__ import unicode_literals
+
+import pytest
+from spacy.matcher import Matcher
+from spacy.tokens import Doc
+
+
+@pytest.mark.xfail
+def test_issue3951(en_vocab):
+    """Test that combinations of optional rules are matched correctly."""
+    matcher = Matcher(en_vocab)
+    pattern = [
+        {"LOWER": "hello"},
+        {"LOWER": "this", "OP": "?"},
+        {"OP": "?"},
+        {"LOWER": "world"},
+    ]
+    matcher.add("TEST", None, pattern)
+    doc = Doc(en_vocab, words=["Hello", "my", "new", "world"])
+    matches = matcher(doc)
+    assert len(matches) == 0