def test_keep_alive_argument(capture):
    n_inst = ConstructorStats.detail_reg_inst()
    with capture:
        p = m.Parent()
    assert capture == "Allocating parent."
    with capture:
        p.addChild(m.Child())
        assert ConstructorStats.detail_reg_inst() == n_inst + 1
    assert capture == """
        Allocating child.
        Releasing child.
    """
    with capture:
        del p
        assert ConstructorStats.detail_reg_inst() == n_inst
    assert capture == "Releasing parent."

    with capture:
        p = m.Parent()
    assert capture == "Allocating parent."
    with capture:
        p.addChildKeepAlive(m.Child())
        assert ConstructorStats.detail_reg_inst() == n_inst + 2
    assert capture == "Allocating child."
    with capture:
        del p
        assert ConstructorStats.detail_reg_inst() == n_inst
    assert capture == """

def test_return_none(capture):
    n_inst = ConstructorStats.detail_reg_inst()
    with capture:
        p = m.Parent()
    assert capture == "Allocating parent."
    with capture:
        p.returnNullChildKeepAliveChild()
        assert ConstructorStats.detail_reg_inst() == n_inst + 1
    assert capture == ""
    with capture:
        del p
        assert ConstructorStats.detail_reg_inst() == n_inst
    assert capture == "Releasing parent."

    with capture:
        p = m.Parent()
    assert capture == "Allocating parent."
    with capture:
        p.returnNullChildKeepAliveParent()
        assert ConstructorStats.detail_reg_inst() == n_inst + 1
    assert capture == ""
    with capture:
        del p
        assert ConstructorStats.detail_reg_inst() == n_inst
    assert capture == "Releasing parent."

def test_keep_alive_return_value(capture):
    from pybind11_tests import Parent, ConstructorStats

    n_inst = ConstructorStats.detail_reg_inst()
    with capture:
        p = Parent()
    assert capture == "Allocating parent."
    with capture:
        p.returnChild()
        assert ConstructorStats.detail_reg_inst() == n_inst + 1
    assert capture == """
        Allocating child.
        Releasing child.
    """
    with capture:
        del p
        assert ConstructorStats.detail_reg_inst() == n_inst
    assert capture == "Releasing parent."

    with capture:
        p = Parent()
    assert capture == "Allocating parent."
    with capture:
        p.returnChildKeepAlive()
        assert ConstructorStats.detail_reg_inst() == n_inst + 2
    assert capture == "Allocating child."
    with capture:
        del p
        assert ConstructorStats.detail_reg_inst() == n_inst
    assert capture == """

def test_pointers(msg):
    from pybind11_tests import (return_void_ptr, get_void_ptr_value, ExampleMandA,
                                print_opaque_list, return_null_str, get_null_str_value,
                                return_unique_ptr, ConstructorStats)

    living_before = ConstructorStats.get(ExampleMandA).alive()
    assert get_void_ptr_value(return_void_ptr()) == 0x1234
    assert get_void_ptr_value(ExampleMandA())  # Should also work for other C++ types
    assert ConstructorStats.get(ExampleMandA).alive() == living_before

    with pytest.raises(TypeError) as excinfo:
        get_void_ptr_value([1, 2, 3])  # This should not work
    assert msg(excinfo.value) == """
        get_void_ptr_value(): incompatible function arguments. The following argument types are supported:
            1. (arg0: capsule) -> int

        Invoked with: [1, 2, 3]
    """  # noqa: E501 line too long

    assert return_null_str() is None
    assert get_null_str_value(return_null_str()) is not None

    ptr = return_unique_ptr()
    assert "StringList" in repr(ptr)
    assert print_opaque_list(ptr) == "Opaque list: [some value]"

def test_reference_internal():
    from pybind11_tests import ConstructorStats
    from pybind11_tests.submodule import A, B

    b = B()
    assert str(b.get_a1()) == "A[1]"
    assert str(b.a1) == "A[1]"
    assert str(b.get_a2()) == "A[2]"
    assert str(b.a2) == "A[2]"

    b.a1 = A(42)
    b.a2 = A(43)
    assert str(b.get_a1()) == "A[42]"
    assert str(b.a1) == "A[42]"
    assert str(b.get_a2()) == "A[43]"
    assert str(b.a2) == "A[43]"

    astats, bstats = ConstructorStats.get(A), ConstructorStats.get(B)
    assert astats.alive() == 2
    assert bstats.alive() == 1
    del b
    assert astats.alive() == 0
    assert bstats.alive() == 0
    assert astats.values() == ['1', '2', '42', '43']
    assert bstats.values() == []
    assert astats.default_constructions == 0
    assert bstats.default_constructions == 1
    assert astats.copy_constructions == 0
    assert bstats.copy_constructions == 0
    # assert astats.move_constructions >= 0  # Don't invoke any
    # assert bstats.move_constructions >= 0  # Don't invoke any
    assert astats.copy_assignments == 2
    assert bstats.copy_assignments == 0
    assert astats.move_assignments == 0
    assert bstats.move_assignments == 0

def test_unique_nodelete():
    from pybind11_tests import MyObject4
    o = MyObject4(23)
    assert o.value == 23
    cstats = ConstructorStats.get(MyObject4)
    assert cstats.alive() == 1
    del o
    cstats = ConstructorStats.get(MyObject4)
    assert cstats.alive() == 1  # Leak, but that's intentional

def test_alive_gc(capture):
    n_inst = ConstructorStats.detail_reg_inst()
    p = m.ParentGC()
    p.addChildKeepAlive(m.Child())
    assert ConstructorStats.detail_reg_inst() == n_inst + 2
    lst = [p]
    lst.append(lst)   # creates a circular reference
    with capture:
        del p, lst
        assert ConstructorStats.detail_reg_inst() == n_inst
    assert capture == """

def test_alive_gc(capture):
    from pybind11_tests import ParentGC, Child, ConstructorStats

    n_inst = ConstructorStats.detail_reg_inst()
    p = ParentGC()
    p.addChildKeepAlive(Child())
    assert ConstructorStats.detail_reg_inst() == n_inst + 2
    lst = [p]
    lst.append(lst)   # creates a circular reference
    with capture:
        del p, lst
        assert ConstructorStats.detail_reg_inst() == n_inst
    assert capture == """

def test_keep_alive_constructor(capture):
    n_inst = ConstructorStats.detail_reg_inst()

    with capture:
        p = m.Parent(m.Child())
        assert ConstructorStats.detail_reg_inst() == n_inst + 2
    assert capture == """
        Allocating child.
        Allocating parent.
    """
    with capture:
        del p
        assert ConstructorStats.detail_reg_inst() == n_inst
    assert capture == """

def test_large_holder():
    o = m.MyObject5(5)
    assert o.value == 5
    cstats = ConstructorStats.get(m.MyObject5)
    assert cstats.alive() == 1
    del o
    assert cstats.alive() == 0

def test_unique_nodelete():
    o = m.MyObject4(23)
    assert o.value == 23
    cstats = ConstructorStats.get(m.MyObject4)
    assert cstats.alive() == 1
    del o
    assert cstats.alive() == 1  # Leak, but that's intentional

def test_stl_ownership():
    cstats = ConstructorStats.get(m.Placeholder)
    assert cstats.alive() == 0
    r = m.test_stl_ownership()
    assert len(r) == 1
    del r
    assert cstats.alive() == 0

def test_to_python():
    mat = m.Matrix(5, 5)
    assert memoryview(mat).shape == (5, 5)

    assert mat[2, 3] == 0
    mat[2, 3] = 4
    assert mat[2, 3] == 4

    mat2 = np.array(mat, copy=False)
    assert mat2.shape == (5, 5)
    assert abs(mat2).sum() == 4
    assert mat2[2, 3] == 4
    mat2[2, 3] = 5
    assert mat2[2, 3] == 5

    cstats = ConstructorStats.get(m.Matrix)
    assert cstats.alive() == 1
    del mat
    pytest.gc_collect()
    assert cstats.alive() == 1
    del mat2  # holds a mat reference
    pytest.gc_collect()
    assert cstats.alive() == 0
    assert cstats.values() == ["5x5 matrix"]
    assert cstats.copy_constructions == 0
    # assert cstats.move_constructions >= 0  # Don't invoke any
    assert cstats.copy_assignments == 0
    assert cstats.move_assignments == 0

def test_holder_with_addressof_operator():
    # this test must not throw exception from c++
    a = m.TypeForHolderWithAddressOf.make()
    a.print_object_1()
    a.print_object_2()
    a.print_object_3()
    a.print_object_4()

    stats = ConstructorStats.get(m.TypeForHolderWithAddressOf)
    assert stats.alive() == 1

    np = m.TypeForHolderWithAddressOf.make()
    assert stats.alive() == 2
    del a
    assert stats.alive() == 1
    del np
    assert stats.alive() == 0

    b = m.TypeForHolderWithAddressOf.make()
    c = b
    assert b.get() is c.get()
    assert stats.alive() == 1

    del b
    assert stats.alive() == 1

    del c
    assert stats.alive() == 0

def test_to_python():
    m = Matrix(5, 5)

    assert m[2, 3] == 0
    m[2, 3] = 4
    assert m[2, 3] == 4

    m2 = np.array(m, copy=False)
    assert m2.shape == (5, 5)
    assert abs(m2).sum() == 4
    assert m2[2, 3] == 4
    m2[2, 3] = 5
    assert m2[2, 3] == 5

    cstats = ConstructorStats.get(Matrix)
    assert cstats.alive() == 1
    del m
    pytest.gc_collect()
    assert cstats.alive() == 1
    del m2  # holds an m reference
    pytest.gc_collect()
    assert cstats.alive() == 0
    assert cstats.values() == ["5x5 matrix"]
    assert cstats.copy_constructions == 0
    # assert cstats.move_constructions >= 0  # Don't invoke any
    assert cstats.copy_assignments == 0
    assert cstats.move_assignments == 0

def test_shared_ptr_and_references():
    from pybind11_tests.smart_ptr import SharedPtrRef, A

    s = SharedPtrRef()
    stats = ConstructorStats.get(A)
    assert stats.alive() == 2

    ref = s.ref  # init_holder_helper(holder_ptr=false, owned=false)
    assert stats.alive() == 2
    assert s.set_ref(ref)
    with pytest.raises(RuntimeError) as excinfo:
        assert s.set_holder(ref)
    assert "Unable to cast from non-held to held instance" in str(excinfo.value)

    copy = s.copy  # init_holder_helper(holder_ptr=false, owned=true)
    assert stats.alive() == 3
    assert s.set_ref(copy)
    assert s.set_holder(copy)

    holder_ref = s.holder_ref  # init_holder_helper(holder_ptr=true, owned=false)
    assert stats.alive() == 3
    assert s.set_ref(holder_ref)
    assert s.set_holder(holder_ref)

    holder_copy = s.holder_copy  # init_holder_helper(holder_ptr=true, owned=true)
    assert stats.alive() == 3
    assert s.set_ref(holder_copy)
    assert s.set_holder(holder_copy)

    del ref, copy, holder_ref, holder_copy, s
    assert stats.alive() == 0

def test_mi_base_return():
    """Tests returning an offset (non-first MI) base class pointer to a derived instance"""
    from pybind11_tests import (I801B2, I801C, I801D, i801c_b1, i801c_b2, i801d_b1, i801d_b2,
                                i801e_c, i801e_b2)

    n_inst = ConstructorStats.detail_reg_inst()

    c1 = i801c_b1()
    assert type(c1) is I801C
    assert c1.a == 1
    assert c1.b == 2

    d1 = i801d_b1()
    assert type(d1) is I801D
    assert d1.a == 1
    assert d1.b == 2

    assert ConstructorStats.detail_reg_inst() == n_inst + 4

    c2 = i801c_b2()
    assert type(c2) is I801C
    assert c2.a == 1
    assert c2.b == 2

    d2 = i801d_b2()
    assert type(d2) is I801D
    assert d2.a == 1
    assert d2.b == 2

    assert ConstructorStats.detail_reg_inst() == n_inst + 8

    del c2
    assert ConstructorStats.detail_reg_inst() == n_inst + 6
    del c1, d1, d2
    assert ConstructorStats.detail_reg_inst() == n_inst

    # Returning an unregistered derived type with a registered base; we won't
    # pick up the derived type, obviously, but should still work (as an object
    # of whatever type was returned).
    e1 = i801e_c()
    assert type(e1) is I801C
    assert e1.a == 1
    assert e1.b == 2

    e2 = i801e_b2()
    assert type(e2) is I801B2
    assert e2.b == 2

def test_methods_and_attributes():
    instance1 = m.ExampleMandA()
    instance2 = m.ExampleMandA(32)

    instance1.add1(instance2)
    instance1.add2(instance2)
    instance1.add3(instance2)
    instance1.add4(instance2)
    instance1.add5(instance2)
    instance1.add6(32)
    instance1.add7(32)
    instance1.add8(32)
    instance1.add9(32)
    instance1.add10(32)

    assert str(instance1) == "ExampleMandA[value=320]"
    assert str(instance2) == "ExampleMandA[value=32]"
    assert str(instance1.self1()) == "ExampleMandA[value=320]"
    assert str(instance1.self2()) == "ExampleMandA[value=320]"
    assert str(instance1.self3()) == "ExampleMandA[value=320]"
    assert str(instance1.self4()) == "ExampleMandA[value=320]"
    assert str(instance1.self5()) == "ExampleMandA[value=320]"

    assert instance1.internal1() == 320
    assert instance1.internal2() == 320
    assert instance1.internal3() == 320
    assert instance1.internal4() == 320
    assert instance1.internal5() == 320

    assert instance1.overloaded() == "()"
    assert instance1.overloaded(0) == "(int)"
    assert instance1.overloaded(1, 1.0) == "(int, float)"
    assert instance1.overloaded(2.0, 2) == "(float, int)"
    assert instance1.overloaded(3,   3) == "(int, int)"
    assert instance1.overloaded(4., 4.) == "(float, float)"
    assert instance1.overloaded_const(-3) == "(int) const"
    assert instance1.overloaded_const(5, 5.0) == "(int, float) const"
    assert instance1.overloaded_const(6.0, 6) == "(float, int) const"
    assert instance1.overloaded_const(7,   7) == "(int, int) const"
    assert instance1.overloaded_const(8., 8.) == "(float, float) const"
    assert instance1.overloaded_float(1, 1) == "(float, float)"
    assert instance1.overloaded_float(1, 1.) == "(float, float)"
    assert instance1.overloaded_float(1., 1) == "(float, float)"
    assert instance1.overloaded_float(1., 1.) == "(float, float)"

    assert instance1.value == 320
    instance1.value = 100
    assert str(instance1) == "ExampleMandA[value=100]"

    cstats = ConstructorStats.get(m.ExampleMandA)
    assert cstats.alive() == 2
    del instance1, instance2
    assert cstats.alive() == 0
    assert cstats.values() == ["32"]
    assert cstats.default_constructions == 1
    assert cstats.copy_constructions == 3
    assert cstats.move_constructions >= 1
    assert cstats.copy_assignments == 0
    assert cstats.move_assignments == 0

def test_move_support():
    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()
    assert ncv1.print_nc(2, 3) == "36"
    assert ncv1.print_movable(4, 5) == "9"
    ncv2 = NCVirtExt2()
    assert ncv2.print_movable(7, 7) == "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

def test_alive_gc_multi_derived(capture):
    from pybind11_tests import Parent, Child, ConstructorStats

    class Derived(Parent, Child):
        pass

    n_inst = ConstructorStats.detail_reg_inst()
    p = Derived()
    p.addChildKeepAlive(Child())
    # +3 rather than +2 because Derived corresponds to two registered instances
    assert ConstructorStats.detail_reg_inst() == n_inst + 3
    lst = [p]
    lst.append(lst)   # creates a circular reference
    with capture:
        del p, lst
        assert ConstructorStats.detail_reg_inst() == n_inst
    assert capture == """