code: def test_cache_failure(self):
      call_count = 0
  
      class FailureProvider(auth.AuthProvider):
          def authenticate(self, environ):
              nonlocal call_count
              call_count += 1
              raise RuntimeError()
  
      providers = {FailureProvider: FailureProvider()}
      auth_ctx = auth.AuthContext(providers, {})
      with self.assertRaises(RuntimeError):
          auth_ctx.get(FailureProvider)
      with self.assertRaises(RuntimeError):
          auth_ctx.get(FailureProvider)
      self.assertEqual(call_count, 2)
  
imports: from tensorboard import auth
  from tensorboard import test
label_desc: Use image node_id 2 for calling the AuthContextTest obj's underlying member method code with example usage: obj.test_cache_failure() without return types