docstr: Test initialization with a valid name.
docstr_tok: ["Test","initialization","with","a","valid","name","."]
code: def test_initialization_valid_name(self):
      """Test initialization with a valid name."""
      policy = DTypePolicy("mixed_float16")
      self.assertEqual(policy.compute_dtype, "float16")
      self.assertEqual(policy.variable_dtype, "float32")
  
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 1 for calling the DTypePolicyTest obj's underlying member method code with example usage: obj.test_initialization_valid_name() without return types