text: import itertools
  import random
  import pytest
  from ethereum.db import _EphemDB
  from ethereum.utils import ascii_chr
  
  random.seed(0)
  
  
  def random_string(length):
      return b''.join([ascii_chr(random.randint(0, 255)) for _ in range(length)])
  
  
  content = {random_string(lk): random_string(lv)
             for lk, lv in itertools.product([1, 32, 255], [0, 1, 32, 255])}
  alt_content = {key: random_string(32) for key in content}
  
  
  def test_ephem():
      db = _EphemDB()
      for key in content:
          assert key not in db
          with pytest.raises(KeyError):
              db.get(key)
      for key, value in content.items():
          db.put(key, value)
          assert key in db
          assert db.get(key) == value
      for key in content:
          db.put(key, alt_content[key])
          assert key in db
          assert db.get(key) == alt_content[key]
      for key, value in content.items():
          db.delete(key)
          assert key not in db
          with pytest.raises(KeyError):
              db.get(key)
  