code: def test_empty_field():
      schema = fields.Schema(id=fields.STORED, key=fields.KEYWORD)
      with TempIndex(schema, "emptysort") as ix:
          w = ix.writer()
          w.add_document(id=1)
          w.add_document(id=2)
          w.add_document(id=3)
          w.commit()
  
          with ix.searcher() as s:
              r = s.search(query.Every(), sortedby="key")
              assert [h["id"] for h in r] == [1, 2, 3]
  
imports: from __future__ import with_statement
  from datetime import datetime, timedelta
  import random
  from whoosh import fields, query, sorting, columns
  from whoosh.compat import u
  from whoosh.compat import permutations, xrange
  from whoosh.filedb.filestore import RamStorage
  from whoosh.util.testing import TempIndex
label_desc: Use image node_id 8 for calling a global function with example usage: test_empty_field() without return types