code: def test_tzCacheRootLookup(self):
      # Test that if cache path in read-only filesystem, no exception.
      tkr = "AMZN"
      # During attempt to lookup, will discover cannot write
      yf.utils.get_tz_cache().lookup(tkr)
  
      # Handling the lookup failure replaces cache with a dummy
      cache = yf.utils.get_tz_cache()
      self.assertTrue(cache.dummy)
      cache.lookup(tkr)
  
file_path: yfinance/tests/utils.py
imports: from .context import yfinance
  import unittest
  import tempfile
  import os
label_desc: Use image node_id 3 for calling the TestCacheNoPermission obj's underlying member method code with example usage: obj.test_tzCacheRootLookup() without return types