summaryrefslogtreecommitdiffstats
path: root/Lib/test/test_importlib/util.py
blob: ef32f7d690fe42ae8a4dd2c82dd5c305cc796cb6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
from contextlib import contextmanager
import imp
import os.path
from test import support
import unittest
import sys


CASE_INSENSITIVE_FS = True
# Windows is the only OS that is *always* case-insensitive
# (OS X *can* be case-sensitive).
if sys.platform not in ('win32', 'cygwin'):
    changed_name = __file__.upper()
    if changed_name == __file__:
        changed_name = __file__.lower()
    if not os.path.exists(changed_name):
        CASE_INSENSITIVE_FS = False


def case_insensitive_tests(test):
    """Class decorator that nullifies tests requiring a case-insensitive
    file system."""
    return unittest.skipIf(not CASE_INSENSITIVE_FS,
                            "requires a case-insensitive filesystem")(test)


@contextmanager
def uncache(*names):
    """Uncache a module from sys.modules.

    A basic sanity check is performed to prevent uncaching modules that either
    cannot/shouldn't be uncached.

    """
    for name in names:
        if name in ('sys', 'marshal', 'imp'):
            raise ValueError(
                "cannot uncache {0}".format(name))
        try:
            del sys.modules[name]
        except KeyError:
            pass
    try:
        yield
    finally:
        for name in names:
            try:
                del sys.modules[name]
            except KeyError:
                pass

@contextmanager
def import_state(**kwargs):
    """Context manager to manage the various importers and stored state in the
    sys module.

    The 'modules' attribute is not supported as the interpreter state stores a
    pointer to the dict that the interpreter uses internally;
    reassigning to sys.modules does not have the desired effect.

    """
    originals = {}
    try:
        for attr, default in (('meta_path', []), ('path', []),
                              ('path_hooks', []),
                              ('path_importer_cache', {})):
            originals[attr] = getattr(sys, attr)
            if attr in kwargs:
                new_value = kwargs[attr]
                del kwargs[attr]
            else:
                new_value = default
            setattr(sys, attr, new_value)
        if len(kwargs):
            raise ValueError(
                    'unrecognized arguments: {0}'.format(kwargs.keys()))
        yield
    finally:
        for attr, value in originals.items():
            setattr(sys, attr, value)


class mock_modules:

    """A mock importer/loader."""

    def __init__(self, *names, module_code={}):
        self.modules = {}
        self.module_code = {}
        for name in names:
            if not name.endswith('.__init__'):
                import_name = name
            else:
                import_name = name[:-len('.__init__')]
            if '.' not in name:
                package = None
            elif import_name == name:
                package = name.rsplit('.', 1)[0]
            else:
                package = import_name
            module = imp.new_module(import_name)
            module.__loader__ = self
            module.__file__ = '<mock __file__>'
            module.__package__ = package
            module.attr = name
            if import_name != name:
                module.__path__ = ['<mock __path__>']
            self.modules[import_name] = module
            if import_name in module_code:
                self.module_code[import_name] = module_code[import_name]

    def __getitem__(self, name):
        return self.modules[name]

    def find_module(self, fullname, path=None):
        if fullname not in self.modules:
            return None
        else:
            return self

    def load_module(self, fullname):
        if fullname not in self.modules:
            raise ImportError
        else:
            sys.modules[fullname] = self.modules[fullname]
            if fullname in self.module_code:
                try:
                    self.module_code[fullname]()
                except Exception:
                    del sys.modules[fullname]
                    raise
            return self.modules[fullname]

    def __enter__(self):
        self._uncache = uncache(*self.modules.keys())
        self._uncache.__enter__()
        return self

    def __exit__(self, *exc_info):
        self._uncache.__exit__(None, None, None)