_parser_test.py

#     https://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.

import numpy as np
import pytest
import sympy

import cirq
import cirq.testing as ct
from cirq import Circuit
from cirq.circuits.qasm_output import QasmUGate
from cirq.contrib.qasm_import import QasmException
from cirq.contrib.qasm_import._parser import QasmParser


def test_format_header_circuit():
    parser = QasmParser()

    parsed_qasm = parser.parse("OPENQASM 2.0;")

    assert parsed_qasm.supportedFormat
    assert not parsed_qasm.qelib1Include
    ct.assert_same_circuits(parsed_qasm.circuit, Circuit())


def test_unsupported_format():
    qasm = "OPENQASM 2.1;"
    parser = QasmParser()

    with pytest.raises(QasmException, match="Unsupported.*2.1.*2.0.*supported.*"):
        parser.parse(qasm)


def test_format_header_with_quelibinc_circuit():
    qasm = """OPENQASM 2.0;
include "qelib1.inc";
"""
    parser = QasmParser()

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include
    ct.assert_same_circuits(parsed_qasm.circuit, Circuit())


@pytest.mark.parametrize(
    'qasm',
    [
        "include \"qelib1.inc\";",
        "",
        "qreg q[3];",
    ],
)
def test_error_not_starting_with_format(qasm: str):
    parser = QasmParser()

    with pytest.raises(QasmException, match="Missing 'OPENQASM 2.0;' statement"):
        parser.parse(qasm)


def test_comments():
    parser = QasmParser()

    parsed_qasm = parser.parse(
        """
    //this is the format
    OPENQASM 2.0;
    // this is some other comment
    include "qelib1.inc";
    // and something at the end of the file
    // multiline
    """
    )

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include
    ct.assert_same_circuits(parsed_qasm.circuit, Circuit())


def test_multiple_qreg_declaration():
    qasm = """OPENQASM 2.0;
     include "qelib1.inc";
     qreg a_quantum_register [ 1337 ];
     qreg q[42];
"""
    parser = QasmParser()

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include
    ct.assert_same_circuits(parsed_qasm.circuit, Circuit())
    assert parsed_qasm.qregs == {'a_quantum_register': 1337, 'q': 42}


@pytest.mark.parametrize(
    'qasm',
    [
        """OPENQASM 2.0;
           qreg q[2];
           creg q[3];
               """,
        """OPENQASM 2.0;
           creg q[2];
           qreg q[3];
               """,
    ],
)
def test_already_defined_error(qasm: str):
    parser = QasmParser()

    with pytest.raises(QasmException, match=r"q.*already defined.* line 3"):
        parser.parse(qasm)


@pytest.mark.parametrize(
    'qasm',
    [
        """OPENQASM 2.0;
           qreg q[0];
               """,
        """OPENQASM 2.0;
           creg q[0];
               """,
    ],
)
def test_zero_length_register(qasm: str):
    parser = QasmParser()

    with pytest.raises(QasmException, match=".* zero-length.*'q'.*line 2"):
        parser.parse(qasm)


def test_unexpected_end_of_file():
    qasm = """OPENQASM 2.0;
              include "qelib1.inc";
              creg
           """
    parser = QasmParser()

    with pytest.raises(QasmException, match="Unexpected end of file"):
        parser.parse(qasm)


def test_multiple_creg_declaration():
    qasm = """OPENQASM 2.0;
     include "qelib1.inc";
     creg a_classical_register [1337];
     qreg a_quantum_register [1337];
     creg c[42];
"""
    parser = QasmParser()

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include
    ct.assert_same_circuits(parsed_qasm.circuit, Circuit())
    assert parsed_qasm.qregs == {'a_quantum_register': 1337}
    assert parsed_qasm.cregs == {'a_classical_register': 1337, 'c': 42}


def test_syntax_error():
    qasm = """OPENQASM 2.0;
         qreg q[2] bla;
         foobar q[0];
    """
    parser = QasmParser()

    with pytest.raises(QasmException, match=r"""Syntax error: 'bla'.*"""):
        parser.parse(qasm)


def test_CX_gate():
    qasm = """OPENQASM 2.0;
     qreg q1[2];
     qreg q2[2];
     CX q1[0], q1[1];
     CX q1, q2[0];
     CX q2, q1;      
"""
    parser = QasmParser()

    q1_0 = cirq.NamedQubit('q1_0')
    q1_1 = cirq.NamedQubit('q1_1')
    q2_0 = cirq.NamedQubit('q2_0')
    q2_1 = cirq.NamedQubit('q2_1')

    expected_circuit = Circuit()
    # CX q1[0], q1[1];
    expected_circuit.append(cirq.CNOT(q1_0, q1_1))
    # CX q1, q2[0];
    expected_circuit.append(cirq.CNOT(q1_0, q2_0))
    expected_circuit.append(cirq.CNOT(q1_1, q2_0))
    # CX q2, q1;
    expected_circuit.append(cirq.CNOT(q2_0, q1_0))
    expected_circuit.append(cirq.CNOT(q2_1, q1_1))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert not parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q1': 2, 'q2': 2}


def test_CX_gate_not_enough_args():
    qasm = """OPENQASM 2.0;
     qreg q[2];
     CX q[0];
"""
    parser = QasmParser()

    with pytest.raises(QasmException, match=r"CX.*takes.*got.*1.*line 3"):
        parser.parse(qasm)


def test_CX_gate_mismatched_registers():
    qasm = """OPENQASM 2.0;
     qreg q1[2];
     qreg q2[3];
     CX q1, q2;
"""
    parser = QasmParser()

    with pytest.raises(QasmException, match=r"Non matching.*length \[2 3\].*line 4"):
        parser.parse(qasm)


def test_CX_gate_bounds():
    qasm = """OPENQASM 2.0;
     qreg q1[2];
     qreg q2[3];
     CX q1[4], q2[0];
"""
    parser = QasmParser()

    with pytest.raises(QasmException, match=r"Out of bounds.*4.*q1.*2.*line 4"):
        parser.parse(qasm)


def test_CX_gate_arg_overlap():
    qasm = """OPENQASM 2.0;
     qreg q1[2];
     qreg q2[3];
     CX q1[1], q1[1];
"""
    parser = QasmParser()

    with pytest.raises(QasmException, match=r"Overlapping.*at line 4"):
        parser.parse(qasm)


def test_U_gate():
    qasm = """
     OPENQASM 2.0;
     qreg q[2];
     U(pi, 2.3, 3) q[0];
     U(+3.14, -pi, (8)) q;
"""
    parser = QasmParser()

    q0 = cirq.NamedQubit('q_0')
    q1 = cirq.NamedQubit('q_1')

    expected_circuit = Circuit()
    expected_circuit.append(
        cirq.Moment(
            [
                QasmUGate(1.0, 2.3 / np.pi, 3 / np.pi)(q0),
                QasmUGate(3.14 / np.pi, -1.0, 8 / np.pi)(q1),
            ]
        )
    )

    expected_circuit.append(cirq.Moment([QasmUGate(3.14 / np.pi, -1.0, 8 / np.pi)(q0)]))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert not parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q': 2}


def test_U_angles():
    qasm = """
    OPENQASM 2.0;
    qreg q[1];
    U(pi/2,0,pi) q[0];
    """

    c = QasmParser().parse(qasm).circuit
    cirq.testing.assert_allclose_up_to_global_phase(
        cirq.unitary(c), cirq.unitary(cirq.H), atol=1e-7
    )


def test_U_gate_zero_params_error():
    qasm = """OPENQASM 2.0;
     qreg q[2];     
     U q[1];"""

    parser = QasmParser()

    with pytest.raises(QasmException, match=r"U takes 3.*got.*0.*line 3"):
        parser.parse(qasm)


def test_U_gate_too_much_params_error():
    qasm = """OPENQASM 2.0;
     qreg q[2];     
     U(pi, pi, pi, pi) q[1];"""

    parser = QasmParser()

    with pytest.raises(QasmException, match=r"U takes 3.*got.*4.*line 3"):
        parser.parse(qasm)


@pytest.mark.parametrize(
    'expr',
    [
        '.333 + 4',
        '1.0 * 2',
        '0.1 ^ pi',
        '0.1 / pi',
        '2.0e-05 ^ (1/2)',
        '1.2E+05 * (3 + 2)',
        '123123.2132312 * cos(pi)',
        '123123.2132312 * sin(2 * pi)',
        '3 - 4 * 2',  # precedence of *
        '3 * 4 + 2',  # precedence of *
        '3 * 4 ^ 2',  # precedence of ^
        '3 - 4 ^ 2',  # precedence of ^
        '3^2^(-2)',  # right associativity of ^
        '(-1) * pi',
        '(+1) * pi',
        '-3 * 5 + 2',
        '(+4 * (-3) ^ 5 - 2)',
        'tan(123123.2132312)',
        'ln(pi)',
        'exp(2*pi)',
        'sqrt(4)',
        'acos(1)',
        'atan(0.2)',
    ],
)
def test_expressions(expr: str):
    qasm = f"""OPENQASM 2.0;
     qreg q[1];
     U({expr}, 2 * pi, pi / 2.0) q[0];
"""

    parser = QasmParser()

    q0 = cirq.NamedQubit('q_0')

    expected_circuit = Circuit()
    expected_circuit.append(QasmUGate(float(sympy.sympify(expr)) / np.pi, 2.0, 1 / 2.0)(q0))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert not parsed_qasm.qelib1Include

    ct.assert_allclose_up_to_global_phase(
        cirq.unitary(parsed_qasm.circuit), cirq.unitary(expected_circuit), atol=1e-10
    )
    assert parsed_qasm.qregs == {'q': 1}


def test_unknown_function():
    qasm = """OPENQASM 2.0;
     qreg q[1];
     U(nonexistent(3), 2 * pi, pi / 3.0) q[0];
"""
    parser = QasmParser()

    with pytest.raises(QasmException, match=r".*not recognized.*'nonexistent'.*line 3"):
        parser.parse(qasm)


rotation_gates = [
    ('rx', cirq.rx),
    ('ry', cirq.ry),
    ('rz', cirq.rz),
]


single_qubit_gates = [
    ('x', cirq.X),
    ('y', cirq.Y),
    ('z', cirq.Z),
    ('h', cirq.H),
    ('s', cirq.S),
    ('t', cirq.T),
    ('sdg', cirq.S ** -1),
    ('tdg', cirq.T ** -1),
    ('sx', cirq.XPowGate(exponent=0.5)),
]


@pytest.mark.parametrize('qasm_gate,cirq_gate', rotation_gates)
def test_rotation_gates(qasm_gate: str, cirq_gate: cirq.SingleQubitGate):
    qasm = """OPENQASM 2.0;
     include "qelib1.inc";
     qreg q[2];
     {0}(pi/2) q[0];
     {0}(pi) q;
    """.format(
        qasm_gate
    )

    parser = QasmParser()

    q0 = cirq.NamedQubit('q_0')
    q1 = cirq.NamedQubit('q_1')

    expected_circuit = Circuit()
    expected_circuit.append(cirq.Moment([cirq_gate(np.pi / 2).on(q0), cirq_gate(np.pi).on(q1)]))
    expected_circuit.append(
        cirq.Moment(
            [
                cirq_gate(np.pi).on(q0),
            ]
        )
    )

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q': 2}


@pytest.mark.parametrize('qasm_gate', [g[0] for g in rotation_gates])
def test_rotation_gates_wrong_number_of_args(qasm_gate: str):
    qasm = f"""
     OPENQASM 2.0;
     include "qelib1.inc";             
     qreg q[2];     
     {qasm_gate}(pi) q[0], q[1];     
"""

    parser = QasmParser()

    with pytest.raises(QasmException, match=r".*{}.* takes 1.*got.*2.*line 5".format(qasm_gate)):
        parser.parse(qasm)


@pytest.mark.parametrize('qasm_gate', [g[0] for g in rotation_gates])
def test_rotation_gates_zero_params_error(qasm_gate: str):
    qasm = f"""OPENQASM 2.0;
     include "qelib1.inc";             
     qreg q[2];     
     {qasm_gate} q[1];     
"""

    parser = QasmParser()

    with pytest.raises(QasmException, match=r".*{}.* takes 1.*got.*0.*line 4".format(qasm_gate)):
        parser.parse(qasm)


def test_qelib_gate_without_include_statement():
    qasm = """OPENQASM 2.0;
         qreg q[2];
         x q[0];
    """
    parser = QasmParser()

    with pytest.raises(QasmException, match=r"""Unknown gate "x".* line 3.*forget.*\?"""):
        parser.parse(qasm)


def test_undefined_register_from_qubit_arg():
    qasm = """OPENQASM 2.0;
            qreg q[2];
            CX q[0], q2[1];
       """
    parser = QasmParser()

    with pytest.raises(QasmException, match=r"""Undefined.*register.*q2.*"""):
        parser.parse(qasm)


def test_undefined_register_from_register_arg():
    qasm = """OPENQASM 2.0;
            qreg q[2];
            qreg q2[2];
            CX q1, q2;
       """
    parser = QasmParser()

    with pytest.raises(QasmException, match=r"""Undefined.*register.*q.*"""):
        parser.parse(qasm)


def test_measure_individual_bits():
    qasm = """
         OPENQASM 2.0;
         include "qelib1.inc";
         qreg q1[2];
         creg c1[2];                        
         measure q1[0] -> c1[0];
         measure q1[1] -> c1[1];
    """
    parser = QasmParser()

    q1_0 = cirq.NamedQubit('q1_0')
    q1_1 = cirq.NamedQubit('q1_1')

    expected_circuit = Circuit()

    expected_circuit.append(cirq.MeasurementGate(num_qubits=1, key='c1_0').on(q1_0))
    expected_circuit.append(cirq.MeasurementGate(num_qubits=1, key='c1_1').on(q1_1))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q1': 2}
    assert parsed_qasm.cregs == {'c1': 2}


def test_measure_registers():
    qasm = """OPENQASM 2.0;
         include "qelib1.inc";
         qreg q1[3];
         creg c1[3];                        
         measure q1 -> c1;       
    """
    parser = QasmParser()

    q1_0 = cirq.NamedQubit('q1_0')
    q1_1 = cirq.NamedQubit('q1_1')
    q1_2 = cirq.NamedQubit('q1_2')

    expected_circuit = Circuit()

    expected_circuit.append(cirq.MeasurementGate(num_qubits=1, key='c1_0').on(q1_0))
    expected_circuit.append(cirq.MeasurementGate(num_qubits=1, key='c1_1').on(q1_1))
    expected_circuit.append(cirq.MeasurementGate(num_qubits=1, key='c1_2').on(q1_2))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q1': 3}
    assert parsed_qasm.cregs == {'c1': 3}


def test_measure_mismatched_register_size():
    qasm = """OPENQASM 2.0;
         include "qelib1.inc";       
         qreg q1[2];
         creg c1[3];                        
         measure q1 -> c1;       
    """

    parser = QasmParser()

    with pytest.raises(QasmException, match=r""".*mismatched .* 2 -> 3.*line 5"""):
        parser.parse(qasm)


def test_measure_to_quantum_register():
    qasm = """OPENQASM 2.0;
         include "qelib1.inc";       
         qreg q1[3];
         qreg q2[3];
         creg c1[3];                        
         measure q2 -> q1;       
    """

    parser = QasmParser()

    with pytest.raises(QasmException, match=r"""Undefined classical register.*q1.*line 6"""):
        parser.parse(qasm)


def test_measure_undefined_classical_bit():
    qasm = """OPENQASM 2.0;
         include "qelib1.inc";       
         qreg q1[3];    
         creg c1[3];                        
         measure q1[1] -> c2[1];       
    """

    parser = QasmParser()

    with pytest.raises(QasmException, match=r"""Undefined classical register.*c2.*line 5"""):
        parser.parse(qasm)


def test_measure_from_classical_register():
    qasm = """OPENQASM 2.0;
         include "qelib1.inc";       
         qreg q1[2];
         creg c1[3];                        
         creg c2[3];                        
         measure c1 -> c2;       
    """

    parser = QasmParser()

    with pytest.raises(QasmException, match=r"""Undefined quantum register.*c1.*line 6"""):
        parser.parse(qasm)


def test_measurement_bounds():
    qasm = """OPENQASM 2.0;
     qreg q1[3];
     creg c1[3];                        
     measure q1[0] -> c1[4];  
"""
    parser = QasmParser()

    with pytest.raises(QasmException, match=r"Out of bounds bit.*4.*c1.*size 3.*line 4"):
        parser.parse(qasm)


def test_u1_gate():
    qasm = """
     OPENQASM 2.0;
     include "qelib1.inc";
     qreg q[1];
     u1(pi / 3.0) q[0];    
"""
    parser = QasmParser()

    q0 = cirq.NamedQubit('q_0')

    expected_circuit = Circuit()
    expected_circuit.append(QasmUGate(0, 0, 1.0 / 3.0)(q0))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q': 1}


def test_u2_gate():
    qasm = """
     OPENQASM 2.0;
     include "qelib1.inc";
     qreg q[1];
     u2(2 * pi, pi / 3.0) q[0];    
"""
    parser = QasmParser()

    q0 = cirq.NamedQubit('q_0')

    expected_circuit = Circuit()
    expected_circuit.append(QasmUGate(0.5, 2.0, 1.0 / 3.0)(q0))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q': 1}


def test_id_gate():
    qasm = """
     OPENQASM 2.0;
     include "qelib1.inc";
     qreg q[2];
     id q;           
"""
    parser = QasmParser()

    q0 = cirq.NamedQubit('q_0')
    q1 = cirq.NamedQubit('q_1')

    expected_circuit = Circuit()
    expected_circuit.append(cirq.IdentityGate(num_qubits=1)(q0))
    expected_circuit.append(cirq.IdentityGate(num_qubits=1)(q1))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q': 2}


def test_u3_gate():
    qasm = """
     OPENQASM 2.0;
     include "qelib1.inc";
     qreg q[2];
     u3(pi, 2.3, 3) q[0];
     u3(+3.14, -pi, (8)) q;
"""
    parser = QasmParser()

    q0 = cirq.NamedQubit('q_0')
    q1 = cirq.NamedQubit('q_1')

    expected_circuit = Circuit()
    expected_circuit.append(
        cirq.Moment(
            [
                QasmUGate(1.0, 2.3 / np.pi, 3 / np.pi)(q0),
                QasmUGate(3.14 / np.pi, -1.0, 8 / np.pi)(q1),
            ]
        )
    )

    expected_circuit.append(cirq.Moment([QasmUGate(3.14 / np.pi, -1.0, 8 / np.pi)(q0)]))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q': 2}


def test_r_gate():
    qasm = """
     OPENQASM 2.0;
     include "qelib1.inc";
     qreg q[1];
     r(pi, pi / 2.0) q[0];    
"""
    parser = QasmParser()

    q0 = cirq.NamedQubit('q_0')

    expected_circuit = Circuit()
    expected_circuit.append(QasmUGate(1.0, 0.0, 0.0)(q0))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q': 1}


@pytest.mark.parametrize(
    'qasm_gate',
    [
        'id',
        'u2',
        'u3',
        'r',
    ]
    + [g[0] for g in rotation_gates]
    + [g[0] for g in single_qubit_gates],
)
def test_standard_single_qubit_gates_wrong_number_of_args(qasm_gate):
    qasm = f"""
     OPENQASM 2.0;
     include "qelib1.inc";             
     qreg q[2];     
     {qasm_gate} q[0], q[1];     
"""

    parser = QasmParser()

    with pytest.raises(QasmException, match=r".* takes 1.*got.*2.*line 5"):
        parser.parse(qasm)


@pytest.mark.parametrize(
    ['qasm_gate', 'num_params'],
    [['id', 0], ['u2', 2], ['u3', 3], ['rx', 1], ['ry', 1], ['rz', 1], ['r', 2]]
    + [[g[0], 0] for g in single_qubit_gates],
)
def test_standard_gates_wrong_params_error(qasm_gate: str, num_params: int):
    qasm = f"""OPENQASM 2.0;
     include "qelib1.inc";             
     qreg q[2];     
     {qasm_gate}(pi, 2*pi, 3*pi, 4*pi, 5*pi) q[1];     
"""

    parser = QasmParser()

    with pytest.raises(
        QasmException, match=r".*{}.* takes {}.*got.*5.*line 4".format(qasm_gate, num_params)
    ):
        parser.parse(qasm)

    if num_params == 0:
        return

    qasm = f"""OPENQASM 2.0;
     include "qelib1.inc";             
     qreg q[2];     
     {qasm_gate} q[1];     
    """

    parser = QasmParser()

    with pytest.raises(
        QasmException, match=r".*{}.* takes {}.*got.*0.*line 4".format(qasm_gate, num_params)
    ):
        parser.parse(qasm)


two_qubit_gates = [
    ('cx', cirq.CNOT),
    ('CX', cirq.CNOT),
    ('cz', cirq.CZ),
    ('cy', cirq.ControlledGate(cirq.Y)),
    ('swap', cirq.SWAP),
    ('ch', cirq.ControlledGate(cirq.H)),
]


@pytest.mark.parametrize('qasm_gate,cirq_gate', two_qubit_gates)
def test_two_qubit_gates(qasm_gate: str, cirq_gate: cirq.TwoQubitGate):
    qasm = """
     OPENQASM 2.0;   
     include "qelib1.inc";       
     qreg q1[2];
     qreg q2[2];
     {0} q1[0], q1[1];
     {0} q1, q2[0];
     {0} q2, q1;      
""".format(
        qasm_gate
    )
    parser = QasmParser()

    q1_0 = cirq.NamedQubit('q1_0')
    q1_1 = cirq.NamedQubit('q1_1')
    q2_0 = cirq.NamedQubit('q2_0')
    q2_1 = cirq.NamedQubit('q2_1')

    expected_circuit = Circuit()
    # CX q1[0], q1[1];
    expected_circuit.append(cirq_gate(q1_0, q1_1))
    # CX q1, q2[0];
    expected_circuit.append(cirq_gate(q1_0, q2_0))
    expected_circuit.append(cirq_gate(q1_1, q2_0))
    # CX q2, q1;
    expected_circuit.append(cirq_gate(q2_0, q1_0))
    expected_circuit.append(cirq_gate(q2_1, q1_1))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q1': 2, 'q2': 2}


@pytest.mark.parametrize('qasm_gate', [g[0] for g in two_qubit_gates])
def test_two_qubit_gates_not_enough_args(qasm_gate: str):
    qasm = f"""
     OPENQASM 2.0;    
     include "qelib1.inc";             
     qreg q[2];
     {qasm_gate} q[0];
"""

    parser = QasmParser()

    with pytest.raises(
        QasmException, match=r".*{}.* takes 2 arg\(s\).*got.*1.*line 5".format(qasm_gate)
    ):
        parser.parse(qasm)


@pytest.mark.parametrize('qasm_gate', [g[0] for g in two_qubit_gates])
def test_two_qubit_gates_with_too_much_parameters(qasm_gate: str):
    qasm = f"""
     OPENQASM 2.0;    
     include "qelib1.inc";             
     qreg q[2];
     {qasm_gate}(pi) q[0],q[1];
"""

    parser = QasmParser()

    with pytest.raises(
        QasmException, match=r".*{}.* takes 0 parameter\(s\).*got.*1.*line 5".format(qasm_gate)
    ):
        parser.parse(qasm)


three_qubit_gates = [('ccx', cirq.TOFFOLI), ('cswap', cirq.CSWAP)]


@pytest.mark.parametrize('qasm_gate,cirq_gate', three_qubit_gates)
def test_three_qubit_gates(qasm_gate: str, cirq_gate: cirq.TwoQubitGate):
    qasm = """
     OPENQASM 2.0;
     include "qelib1.inc";       
     qreg q1[2];
     qreg q2[2];
     qreg q3[2];
     {0} q1[0], q1[1], q2[0];
     {0} q1, q2[0], q3[0];
     {0} q1, q2, q3;      
""".format(
        qasm_gate
    )
    parser = QasmParser()

    q1_0 = cirq.NamedQubit('q1_0')
    q1_1 = cirq.NamedQubit('q1_1')
    q2_0 = cirq.NamedQubit('q2_0')
    q2_1 = cirq.NamedQubit('q2_1')
    q3_0 = cirq.NamedQubit('q3_0')
    q3_1 = cirq.NamedQubit('q3_1')

    expected_circuit = Circuit()

    expected_circuit.append(cirq_gate(q1_0, q1_1, q2_0))

    expected_circuit.append(cirq_gate(q1_0, q2_0, q3_0))
    expected_circuit.append(cirq_gate(q1_1, q2_0, q3_0))

    expected_circuit.append(cirq_gate(q1_0, q2_0, q3_0))
    expected_circuit.append(cirq_gate(q1_1, q2_1, q3_1))

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q1': 2, 'q2': 2, 'q3': 2}


@pytest.mark.parametrize('qasm_gate', [g[0] for g in three_qubit_gates])
def test_three_qubit_gates_not_enough_args(qasm_gate: str):
    qasm = f"""OPENQASM 2.0;
     include "qelib1.inc";
     qreg q[2];
     {qasm_gate} q[0];
"""

    parser = QasmParser()

    with pytest.raises(
        QasmException, match=r""".*{}.* takes 3 arg\(s\).*got.*1.*line 4""".format(qasm_gate)
    ):
        parser.parse(qasm)


@pytest.mark.parametrize('qasm_gate', [g[0] for g in three_qubit_gates])
def test_three_qubit_gates_with_too_much_parameters(qasm_gate: str):
    qasm = f"""OPENQASM 2.0;
     include "qelib1.inc";
     qreg q[3];
     {qasm_gate}(pi) q[0],q[1],q[2];
"""

    parser = QasmParser()

    with pytest.raises(QasmException, match=r""".*{}.*parameter.*line 4.*""".format(qasm_gate)):
        parser.parse(qasm)


@pytest.mark.parametrize('qasm_gate,cirq_gate', single_qubit_gates)
def test_single_qubit_gates(qasm_gate: str, cirq_gate: cirq.SingleQubitGate):
    qasm = """OPENQASM 2.0;
     include "qelib1.inc";
     qreg q[2];
     {0} q[0];
     {0} q;
    """.format(
        qasm_gate
    )

    parser = QasmParser()

    q0 = cirq.NamedQubit('q_0')
    q1 = cirq.NamedQubit('q_1')

    expected_circuit = Circuit(
        [
            cirq_gate.on(q0),
            cirq_gate.on(q0),
            cirq_gate.on(q1),
        ]
    )

    parsed_qasm = parser.parse(qasm)

    assert parsed_qasm.supportedFormat
    assert parsed_qasm.qelib1Include

    ct.assert_same_circuits(parsed_qasm.circuit, expected_circuit)
    assert parsed_qasm.qregs == {'q': 2}