class_docstr: State tests.
class_docstr_tok: ["State","tests","."]
docstr: Test the vacuum state is correct.
docstr_tok: ["Test","the","vacuum","state","is","correct","."]
code: def test_vacuum_state(self, tol):
      """Test the vacuum state is correct."""
      wires = 3
      cov, means = vacuum_state(wires, hbar=hbar)
      assert means == pytest.approx(np.zeros([2 * wires]), abs=tol)
      assert cov == pytest.approx(
          np.identity(2 * wires) * hbar / 2, 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 1 for calling the TestStates obj's underlying member method code with example usage: obj.test_vacuum_state(tol) without return types