docstr: Test that the matrix of a script with only observables is Identity.
code: def test_all_measurement_matrices_are_identity(self, measurements, N):
      """Test that the matrix of a script with only observables is Identity."""
      qscript = qml.tape.QuantumScript(measurements=measurements)
      assert np.array_equal(qml.matrix(qscript), np.eye(N))
  
imports: from functools import reduce, partial
  from warnings import catch_warnings
  import pytest
  from gate_data import I, X, Y, Z, H, S, CNOT, Rotx, Roty
  import pennylane
  from pennylane import numpy
  from pennylane.transforms.op_transforms import OperationTransformError
label_desc: Use image node_id 1 for calling the TestMeasurements obj's underlying member method code with example usage: obj.test_all_measurement_matrices_are_identity(measurements, N) without return types