check for empty dawg

cfbolz · Nov 3, 2023 · dfb0580 · dfb0580
1 parent d49e871
commit dfb0580
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diff --git a/Lib/test/test_tools/test_makeunicodedata.py b/Lib/test/test_tools/test_makeunicodedata.py
@@ -55,6 +55,10 @@ def test_dawg_direct_simple(self):
         self.assertEqual(inverse_lookup(packed, inverse, 5), b"zcatnip")
         self.assertRaises(KeyError, inverse_lookup, packed, inverse, 12)
 
+    def test_forbid_empty_dawg(self):
+        dawg = Dawg()
+        self.assertRaises(ValueError, dawg.finish)
+
     @given(char_name_db())
     @example([("abc", "a"), ("abd", "b")])
     @example(

diff --git a/Tools/unicode/dawg.py b/Tools/unicode/dawg.py
@@ -133,6 +133,8 @@ def insert(self, word, value):
         self.previous_word = word
 
     def finish(self):
+        if not self.data:
+            raise ValueError("need at least one word in the dawg")
         # minimize all unchecked_nodes
         self._minimize(0)