class_docstr: Test that the user-defined dtype of the device is preserved for QNode
  evaluation
docstr: Test that the user-defined dtype of the device is preserved
  for QNodes with real-valued outputs
docstr_tok: ["Test","that","the","user-defined","dtype","of","the","device","is","preserved","for","QNodes","with","real-valued","outputs"]
code: def test_real_dtype(self, r_dtype, measurement):
      """Test that the user-defined dtype of the device is preserved
      for QNodes with real-valued outputs"""
      p = tf.constant(0.543)
  
      dev = qml.device("default.mixed", wires=3, r_dtype=r_dtype)
  
      @qml.qnode(dev, interface="tf", diff_method="backprop")
      def circuit(x):
          qml.RX(x, wires=0)
          return qml.apply(measurement)
  
      res = circuit(p)
      assert res.dtype == r_dtype
  
imports: import pytest
  import numpy
  import pennylane
  from pennylane import numpy
  from pennylane.devices.default_mixed import DefaultMixed
label_desc: Use image node_id 1 for calling the TestDtypePreserved obj's underlying member method code with example usage: obj.test_real_dtype(r_dtype, measurement) and returns: qml