test_copy_move.py revision 12391 
1import pytest
2from pybind11_tests import copy_move_policies as m
3
4
5def test_lacking_copy_ctor():
6    with pytest.raises(RuntimeError) as excinfo:
7        m.lacking_copy_ctor.get_one()
8    assert "the object is non-copyable!" in str(excinfo.value)
9
10
11def test_lacking_move_ctor():
12    with pytest.raises(RuntimeError) as excinfo:
13        m.lacking_move_ctor.get_one()
14    assert "the object is neither movable nor copyable!" in str(excinfo.value)
15
16
17def test_move_and_copy_casts():
18    """Cast some values in C++ via custom type casters and count the number of moves/copies."""
19
20    cstats = m.move_and_copy_cstats()
21    c_m, c_mc, c_c = cstats["MoveOnlyInt"], cstats["MoveOrCopyInt"], cstats["CopyOnlyInt"]
22
23    # The type move constructions/assignments below each get incremented: the move assignment comes
24    # from the type_caster load; the move construction happens when extracting that via a cast or
25    # loading into an argument.
26    assert m.move_and_copy_casts(3) == 18
27    assert c_m.copy_assignments + c_m.copy_constructions == 0
28    assert c_m.move_assignments == 2
29    assert c_m.move_constructions >= 2
30    assert c_mc.alive() == 0
31    assert c_mc.copy_assignments + c_mc.copy_constructions == 0
32    assert c_mc.move_assignments == 2
33    assert c_mc.move_constructions >= 2
34    assert c_c.alive() == 0
35    assert c_c.copy_assignments == 2
36    assert c_c.copy_constructions >= 2
37    assert c_m.alive() + c_mc.alive() + c_c.alive() == 0
38
39
40def test_move_and_copy_loads():
41    """Call some functions that load arguments via custom type casters and count the number of
42    moves/copies."""
43
44    cstats = m.move_and_copy_cstats()
45    c_m, c_mc, c_c = cstats["MoveOnlyInt"], cstats["MoveOrCopyInt"], cstats["CopyOnlyInt"]
46
47    assert m.move_only(10) == 10  # 1 move, c_m
48    assert m.move_or_copy(11) == 11  # 1 move, c_mc
49    assert m.copy_only(12) == 12  # 1 copy, c_c
50    assert m.move_pair((13, 14)) == 27  # 1 c_m move, 1 c_mc move
51    assert m.move_tuple((15, 16, 17)) == 48  # 2 c_m moves, 1 c_mc move
52    assert m.copy_tuple((18, 19)) == 37  # 2 c_c copies
53    # Direct constructions: 2 c_m moves, 2 c_mc moves, 1 c_c copy
54    # Extra moves/copies when moving pairs/tuples: 3 c_m, 3 c_mc, 2 c_c
55    assert m.move_copy_nested((1, ((2, 3, (4,)), 5))) == 15
56
57    assert c_m.copy_assignments + c_m.copy_constructions == 0
58    assert c_m.move_assignments == 6
59    assert c_m.move_constructions == 9
60    assert c_mc.copy_assignments + c_mc.copy_constructions == 0
61    assert c_mc.move_assignments == 5
62    assert c_mc.move_constructions == 8
63    assert c_c.copy_assignments == 4
64    assert c_c.copy_constructions == 6
65    assert c_m.alive() + c_mc.alive() + c_c.alive() == 0
66
67
68@pytest.mark.skipif(not m.has_optional, reason='no <optional>')
69def test_move_and_copy_load_optional():
70    """Tests move/copy loads of std::optional arguments"""
71
72    cstats = m.move_and_copy_cstats()
73    c_m, c_mc, c_c = cstats["MoveOnlyInt"], cstats["MoveOrCopyInt"], cstats["CopyOnlyInt"]
74
75    # The extra move/copy constructions below come from the std::optional move (which has to move
76    # its arguments):
77    assert m.move_optional(10) == 10  # c_m: 1 move assign, 2 move construct
78    assert m.move_or_copy_optional(11) == 11  # c_mc: 1 move assign, 2 move construct
79    assert m.copy_optional(12) == 12  # c_c: 1 copy assign, 2 copy construct
80    # 1 move assign + move construct moves each of c_m, c_mc, 1 c_c copy
81    # +1 move/copy construct each from moving the tuple
82    # +1 move/copy construct each from moving the optional (which moves the tuple again)
83    assert m.move_optional_tuple((3, 4, 5)) == 12
84
85    assert c_m.copy_assignments + c_m.copy_constructions == 0
86    assert c_m.move_assignments == 2
87    assert c_m.move_constructions == 5
88    assert c_mc.copy_assignments + c_mc.copy_constructions == 0
89    assert c_mc.move_assignments == 2
90    assert c_mc.move_constructions == 5
91    assert c_c.copy_assignments == 2
92    assert c_c.copy_constructions == 5
93    assert c_m.alive() + c_mc.alive() + c_c.alive() == 0
94
95
96def test_private_op_new():
97    """An object with a private `operator new` cannot be returned by value"""
98
99    with pytest.raises(RuntimeError) as excinfo:
100        m.private_op_new_value()
101    assert "the object is neither movable nor copyable" in str(excinfo.value)
102
103    assert m.private_op_new_reference().value == 1
104
105
106def test_move_fallback():
107    """#389: rvp::move should fall-through to copy on non-movable objects"""
108
109    m2 = m.get_moveissue2(2)
110    assert m2.value == 2
111    m1 = m.get_moveissue1(1)
112    assert m1.value == 1
113