docstr: Test initialization behavior with an invalid name.
docstr_tok: ["Test","initialization","behavior","with","an","invalid","name","."]
code: def test_initialization_with_invalid_name_behaviour(self):
      """Test initialization behavior with an invalid name."""
      with self.assertRaisesRegex(ValueError, "Cannot convert"):
          DTypePolicy("invalid_name")
  
imports: from keras.mixed_precision import DTypePolicy
  from keras.mixed_precision import dtype_policy
  from keras.mixed_precision import set_dtype_policy
  from keras.testing import test_case
label_desc: Use image node_id 6 for calling the DTypePolicyTest obj's underlying member method code with example usage: obj.test_initialization_with_invalid_name_behaviour() without return types