Rename importlib.test.support to importlib.test.util.

Lib/importlib/test/util.py

@@ -0,0 +1,153 @@
+from importlib import Import
+
+from contextlib import contextmanager
+from functools import update_wrapper
+import imp
+import os.path
+from test.support import unlink
+import sys
+
+
+using___import__ = False
+
+def import_(*args, **kwargs):
+    """Delegate to allow for injecting different implementations of import."""
+    if using___import__:
+        return __import__(*args, **kwargs)
+    return Import()(*args, **kwargs)
+
+def importlib_only(fxn):
+    """Decorator to mark which tests are not supported by the current
+    implementation of __import__()."""
+    def inner(*args, **kwargs):
+        if using___import__:
+            return
+        else:
+            return fxn(*args, **kwargs)
+    update_wrapper(inner, fxn)
+    return inner
+
+
+def case_insensitive_tests(class_):
+    """Class decorator that nullifies tests that require a case-insensitive
+    file system."""
+    if sys.platform not in ('win32', 'darwin', 'cygwin'):
+        return object()
+    else:
+        return class_
+
+
+@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} as it will break _importlib".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):
+        self.modules = {}
+        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
+
+    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]
+            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)
+
+
+def mock_path_hook(*entries, importer):
+    """A mock sys.path_hooks entry."""
+    def hook(entry):
+        if entry not in entries:
+            raise ImportError
+        return importer
+    return hook