* Extend parse tree navigation tests

tests/test_parse_navigate.py

@@ -26,3 +26,36 @@ def test_consistency(nlp, sun_text):
             assert child.head is head
         for child in head.rights:
             assert child.head is head
+
+
+def test_child_consistency(nlp, sun_text):
+    tokens = nlp(sun_text)
+
+    lefts = {}
+    rights = {}
+    for head in tokens:
+        assert head.i not in lefts
+        lefts[head.i] = set()
+        for left in head.lefts:
+            lefts[head.i].add(left.i)
+        assert head.i not in rights
+        rights[head.i] = set()
+        for right in head.rights:
+            rights[head.i].add(right.i)
+    for head in tokens:
+        assert head.n_rights == len(rights[head.i])
+        assert head.n_lefts == len(lefts[head.i])
+    for child in tokens:
+        if child.i < child.head.i:
+            assert child.i in lefts[child.head.i]
+            assert child.i not in rights[child.head.i]
+            lefts[child.head.i].remove(child.i)
+        elif child.i > child.head.i:
+            assert child.i in rights[child.head.i]
+            assert child.i not in lefts[child.head.i]
+            rights[child.head.i].remove(child.i)
+    for head_index, children in lefts.items():
+        assert not children
+    for head_index, children in rights.items():
+        assert not children
+