message: revising test
diff: @@ -11,7 +11,32 @@ CREATE TABLE strings(s VARCHAR)
  statement ok
  INSERT INTO strings VALUES ('hello'), ('hallo'), ('aloha'), ('hoi'), ('world')
  -# normal length
  +# normal queries
  +query I
  +SELECT levenshtein('hallo', 'hallo')
  +----
  +0
  +
  +query I
  +SELECT levenshtein('hallo', 'hello')
  +----
  +1
  +
  +query I
  +SELECT levenshtein('hallo', 'hoi')
  +----
  +4
  +
  +query I
  +SELECT levenshtein(NULL, 'hoi')
  +----
  +NULL
  +
  +query I
  +SELECT levenshtein('hi', NULL)
  +----
  +NULL
  +
  query I
  SELECT levenshtein(s, 'hallo') FROM strings ORDER BY s
  ----
  @@ -20,3 +45,82 @@ SELECT levenshtein(s, 'hallo') FROM strings ORDER BY s
  1
  4
  4
  +
  +query I
  +SELECT levenshtein('hallo', s) FROM strings ORDER BY s
  +----
  +3
  +0
  +1
  +4
  +3
  +
  +query I
  +SELECT levenshtein(NULL, s) FROM strings
  +----
  +NULL
  +NULL
  +NULL
  +NULL
  +NULL
  +
  +query I
  +SELECT levenshtein(NULL, s) FROM strings
  +----
  +NULL
  +NULL
  +NULL
  +NULL
  +NULL
  +
  +# incorrect usage
  +statement error
  +SELECT mismatches('', 'hallo')
  +
  +statement error
  +SELECT mismatches('hi', '')
  +
  +statement error
  +SELECT mismatches('', NULL)
  +
  +statement error
  +SELECT mismatches(NULL, '')
  +
  +statement error
  +SELECT mismatches('', s) FROM strings
  +
  +statement error
  +SELECT mismatches(s, '') FROM strings
  +
  +
  +statement ok
  +DROP TABLE strings
  +
  +statement ok
  +CREATE TABLE strings(s VARCHAR)
  +
  +statement ok
  +INSERT INTO strings VALUES (NULL)
  +
  +statement error
  +SELECT mismatches('', s) FROM strings
  +
  +statement error
  +SELECT mismatches(s, '') FROM strings
  +
  +
  +
  +statement ok
  +DROP TABLE strings
  +
  +statement ok
  +CREATE TABLE strings(s VARCHAR)
  +
  +statement ok
  +INSERT INTO strings VALUES ('')
  +
  +statement error
  +SELECT mismatches(NULL, s) FROM strings
  +
  +statement error
  +SELECT mismatches(s, NULL) FROM strings
  