pybind11/tests/test_virtual_functions.py

import pytest
from pybind11_tests import ConstructorStats


def test_override(capture, msg):
    from pybind11_tests import (ExampleVirt, runExampleVirt, runExampleVirtVirtual,
                                runExampleVirtBool)

    class ExtendedExampleVirt(ExampleVirt):
        def __init__(self, state):
            super(ExtendedExampleVirt, self).__init__(state + 1)
            self.data = "Hello world"

        def run(self, value):
            print('ExtendedExampleVirt::run(%i), calling parent..' % value)
            return super(ExtendedExampleVirt, self).run(value + 1)

        def run_bool(self):
            print('ExtendedExampleVirt::run_bool()')
            return False

        def pure_virtual(self):
            print('ExtendedExampleVirt::pure_virtual(): %s' % self.data)

    ex12 = ExampleVirt(10)
    with capture:
        assert runExampleVirt(ex12, 20) == 30
    assert capture == "Original implementation of ExampleVirt::run(state=10, value=20)"

    with pytest.raises(RuntimeError) as excinfo:
        runExampleVirtVirtual(ex12)
    assert msg(excinfo.value) == 'Tried to call pure virtual function "ExampleVirt::pure_virtual"'

    ex12p = ExtendedExampleVirt(10)
    with capture:
        assert runExampleVirt(ex12p, 20) == 32
    assert capture == """
        ExtendedExampleVirt::run(20), calling parent..
        Original implementation of ExampleVirt::run(state=11, value=21)
    """
    with capture:
        assert runExampleVirtBool(ex12p) is False
    assert capture == "ExtendedExampleVirt::run_bool()"
    with capture:
        runExampleVirtVirtual(ex12p)
    assert capture == "ExtendedExampleVirt::pure_virtual(): Hello world"

    cstats = ConstructorStats.get(ExampleVirt)
    assert cstats.alive() == 2
    del ex12, ex12p
    assert cstats.alive() == 0
    assert cstats.values() == ['10', '11']
    assert cstats.copy_constructions == 0
    assert cstats.move_constructions >= 0


def test_inheriting_repeat(capture):
    from pybind11_tests import A_Repeat, B_Repeat, C_Repeat, D_Repeat, A_Tpl, B_Tpl, C_Tpl, D_Tpl

    class VI_AR(A_Repeat):
        def unlucky_number(self):
            return 99

    class VI_AT(A_Tpl):
        def unlucky_number(self):
            return 999

    obj = VI_AR()
    with capture:
        obj.say_something(3)
    assert capture == "hihihi"
    assert obj.unlucky_number() == 99

    obj = VI_AT()
    with capture:
        obj.say_something(3)
    assert capture == "hihihi"
    assert obj.unlucky_number() == 999

    for obj in [B_Repeat(), B_Tpl()]:
        with capture:
            obj.say_something(3)
        assert capture == "B says hi 3 times"
        assert obj.unlucky_number() == 13
        assert obj.lucky_number() == 7.0

    for obj in [C_Repeat(), C_Tpl()]:
        with capture:
            obj.say_something(3)
        assert capture == "B says hi 3 times"
        assert obj.unlucky_number() == 4444
        assert obj.lucky_number() == 888.0

    class VI_CR(C_Repeat):
        def lucky_number(self):
            return C_Repeat.lucky_number(self) + 1.25

    obj = VI_CR()
    with capture:
        obj.say_something(3)
    assert capture == "B says hi 3 times"
    assert obj.unlucky_number() == 4444
    assert obj.lucky_number() == 889.25

    class VI_CT(C_Tpl):
        pass

    obj = VI_CT()
    with capture:
        obj.say_something(3)
    assert capture == "B says hi 3 times"
    assert obj.unlucky_number() == 4444
    assert obj.lucky_number() == 888.0

    class VI_CCR(VI_CR):
        def lucky_number(self):
            return VI_CR.lucky_number(self) * 10

    obj = VI_CCR()
    with capture:
        obj.say_something(3)
    assert capture == "B says hi 3 times"
    assert obj.unlucky_number() == 4444
    assert obj.lucky_number() == 8892.5

    class VI_CCT(VI_CT):
        def lucky_number(self):
            return VI_CT.lucky_number(self) * 1000

    obj = VI_CCT()
    with capture:
        obj.say_something(3)
    assert capture == "B says hi 3 times"
    assert obj.unlucky_number() == 4444
    assert obj.lucky_number() == 888000.0

    class VI_DR(D_Repeat):
        def unlucky_number(self):
            return 123

        def lucky_number(self):
            return 42.0

    for obj in [D_Repeat(), D_Tpl()]:
        with capture:
            obj.say_something(3)
        assert capture == "B says hi 3 times"
        assert obj.unlucky_number() == 4444
        assert obj.lucky_number() == 888.0

    obj = VI_DR()
    with capture:
        obj.say_something(3)
    assert capture == "B says hi 3 times"
    assert obj.unlucky_number() == 123
    assert obj.lucky_number() == 42.0

    class VI_DT(D_Tpl):
        def say_something(self, times):
            print("VI_DT says:" + (' quack' * times))

        def unlucky_number(self):
            return 1234

        def lucky_number(self):
            return -4.25

    obj = VI_DT()
    with capture:
        obj.say_something(3)
    assert capture == "VI_DT says: quack quack quack"
    assert obj.unlucky_number() == 1234
    assert obj.lucky_number() == -4.25


def test_move_support(capture):
    from pybind11_tests import NCVirt, NonCopyable, Movable

    class NCVirtExt(NCVirt):
        def get_noncopyable(self, a, b):
            # Constructs and returns a new instance:
            nc = NonCopyable(a*a, b*b)
            return nc

        def get_movable(self, a, b):
            # Return a referenced copy
            self.movable = Movable(a, b)
            return self.movable

    class NCVirtExt2(NCVirt):
        def get_noncopyable(self, a, b):
            # Keep a reference: this is going to throw an exception
            self.nc = NonCopyable(a, b)
            return self.nc

        def get_movable(self, a, b):
            # Return a new instance without storing it
            return Movable(a, b)

    ncv1 = NCVirtExt()
    with capture:
        ncv1.print_nc(2, 3)
    assert capture == "36"
    with capture:
        ncv1.print_movable(4, 5)
    assert capture == "9"
    ncv2 = NCVirtExt2()
    with capture:
        ncv2.print_movable(7, 7)
    assert capture == "14"
    # Don't check the exception message here because it differs under debug/non-debug mode
    with pytest.raises(RuntimeError):
        ncv2.print_nc(9, 9)

    nc_stats = ConstructorStats.get(NonCopyable)
    mv_stats = ConstructorStats.get(Movable)
    assert nc_stats.alive() == 1
    assert mv_stats.alive() == 1
    del ncv1, ncv2
    assert nc_stats.alive() == 0
    assert mv_stats.alive() == 0
    assert nc_stats.values() == ['4', '9', '9', '9']
    assert mv_stats.values() == ['4', '5', '7', '7']
    assert nc_stats.copy_constructions == 0
    assert mv_stats.copy_constructions == 1
    assert nc_stats.move_constructions >= 0
    assert mv_stats.move_constructions >= 0