class_docstr: Test the default gaussian device. The test ensures that the device is properly
  applying gaussian operations and calculating the correct observables.
class_docstr_tok: ["Test","the","default","gaussian","device",".","The","test","ensures","that","the","device","is","properly","applying","gaussian","operations","and","calculating","the","correct","observables","."]
docstr: Test the application of gates to a state, using gates that use the default logic in
  the apply function.
docstr_tok: ["Test","the","application","of","gates","to","a","state",",","using","gates","that","use","the","default","logic","in","the","apply","function","."]
code: def test_apply_general(self, tol):
      """Test the application of gates to a state, using gates that use the default logic in
      the apply function."""
  
      gaussian_dev = qml.device("default.gaussian", wires=1)
  
      def dummy_gate_fn():
          # dummy implementation of a symplectic matrix
          return np.array([[2, 0], [0, 3]])
  
      # temporarily add the gate to the device using an arbitrary implementation
      gaussian_dev._operation_map["DummyGate"] = dummy_gate_fn
  
      gaussian_dev.apply(
          "DummyGate", wires=qml.wires.Wires([0]), par=[]
      )
  
      exp_cov = np.array([[4.0, 0.0], [0.0, 9.0]])
      exp_mu = np.array([0.0, 0.0])
  
      # verify the device is now in the expected state
      assert gaussian_dev._state[0] == pytest.approx(exp_cov, abs=tol)
      assert gaussian_dev._state[1] == pytest.approx(exp_mu, abs=tol)
  
imports: import numpy
  import numpy.random
  import pytest
  from scipy.linalg import block_diag
  from scipy.special import factorial
  import pennylane
  from pennylane import DeviceError
  from pennylane.devices.default_gaussian import fock_prob, rotation, squeezing, quadratic_phase, beamsplitter, two_mode_squeezing, controlled_addition, controlled_phase, vacuum_state, coherent_state, squeezed_state, displaced_squeezed_state, thermal_state
  from pennylane.wires import Wires
label_desc: Use image node_id 3 for calling the TestDefaultGaussianDevice obj's underlying member method code with example usage: obj.test_apply_general(tol) and returns: np