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84 lines
2.3 KiB
84 lines
2.3 KiB
4 years ago
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import contextlib
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import os
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@contextlib.contextmanager
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def temporary_env(newenv):
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"""Completely replace the environment variables with the specified dict.
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Use as a context manager::
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with temporary_env({'PATH': my_path}):
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...
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"""
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orig_env = os.environ.copy()
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os.environ.clear()
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os.environ.update(newenv)
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try:
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yield
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finally:
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os.environ.clear()
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os.environ.update(orig_env)
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@contextlib.contextmanager
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def modified_env(changes, snapshot=True):
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"""Temporarily modify environment variables.
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Specify the changes as a dictionary mapping names to new values, using
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None as the value for names that should be deleted.
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Example use::
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with modified_env({'SHELL': 'bash', 'PYTHONPATH': None}):
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...
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When the context exits, there are two possible ways to restore the
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environment. If *snapshot* is True, the default, it will reset the whole
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environment to its state when the context was entered. If *snapshot* is
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False, it will restore only the specific variables it modified, leaving
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any changes made to other environment variables in the context.
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"""
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def update_del(changes):
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for k, v in changes.items():
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if v is None:
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os.environ.pop(k, None)
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else:
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os.environ[k] = v
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if snapshot:
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saved_variables = os.environ.copy()
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else:
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saved_variables = {}
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for k,v in changes.items():
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saved_variables[k] = os.environ.get(k, None)
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update_del(changes)
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try:
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yield
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finally:
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if snapshot:
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os.environ.clear()
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os.environ.update(saved_variables)
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else:
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update_del(saved_variables)
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def make_env_restorer():
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"""Snapshot the current environment, return a function to restore that.
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This is intended to produce cleanup functions for tests. For example,
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using the :class:`unittest.TestCase` API::
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def setUp(self):
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self.addCleanup(testpath.make_env_restorer())
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Any changes a test makes to the environment variables will be wiped out
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before the next test is run.
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"""
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orig_env = os.environ.copy()
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def restore():
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os.environ.clear()
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os.environ.update(orig_env)
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return restore
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