text: #   Copyright 2018 ProjectQ-Framework (www.projectq.ch)
  #
  #   Licensed under the Apache License, Version 2.0 (the "License");
  #   you may not use this file except in compliance with the License.
  #   You may obtain a copy of the License at
  #
  #       http://www.apache.org/licenses/LICENSE-2.0
  #
  #   Unless required by applicable law or agreed to in writing, software
  #   distributed under the License is distributed on an "AS IS" BASIS,
  #   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  #   See the License for the specific language governing permissions and
  #   limitations under the License.
  
  """Tests for projectq.setups.decompositions.stateprep2cnot."""
  
  import cmath
  from copy import deepcopy
  import math
  
  import numpy as np
  import pytest
  
  import projectq
  from projectq.ops import All, Command, Measure, Ry, Rz, StatePreparation, Ph
  from projectq.setups import restrictedgateset
  from projectq.types import WeakQubitRef
  
  import projectq.setups.decompositions.stateprep2cnot as stateprep2cnot
  
  
  def test_wrong_final_state():
      qb0 = WeakQubitRef(engine=None, idx=0)
      qb1 = WeakQubitRef(engine=None, idx=1)
      cmd = Command(None, StatePreparation([0, 1j]), qubits=([qb0, qb1],))
      with pytest.raises(ValueError):
          stateprep2cnot._decompose_state_preparation(cmd)
  
  
  @pytest.mark.parametrize("zeros", [True, False])
  @pytest.mark.parametrize("n_qubits", [1, 2, 3, 4])
  def test_state_preparation(n_qubits, zeros):
      engine_list = restrictedgateset.get_engine_list(
          one_qubit_gates=(Ry, Rz, Ph))
      eng = projectq.MainEngine(engine_list=engine_list)
      qureg = eng.allocate_qureg(n_qubits)
      eng.flush()
  
      f_state = [0.2+0.1*x*cmath.exp(0.1j+0.2j*x) for x in range(2**n_qubits)]
      if zeros:
          for i in range(2**(n_qubits-1)):
              f_state[i] = 0
      norm = 0
      for amplitude in f_state:
          norm += abs(amplitude)**2
      f_state = [x / math.sqrt(norm) for x in f_state]
  
      StatePreparation(f_state) | qureg
      eng.flush()
  
      wavefunction = deepcopy(eng.backend.cheat()[1])
      # Test that simulator hasn't reordered wavefunction
      mapping = eng.backend.cheat()[0]
      for key in mapping:
          assert mapping[key] == key
      All(Measure) | qureg
      eng.flush()
      assert np.allclose(wavefunction, f_state, rtol=1e-10, atol=1e-10)
  