110 lines
3.5 KiB
ReStructuredText
110 lines
3.5 KiB
ReStructuredText
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.. _`tmpdir handling`:
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.. _tmpdir:
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Temporary directories and files
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================================================
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The 'tmpdir' fixture
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--------------------
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You can use the ``tmpdir`` fixture which will
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provide a temporary directory unique to the test invocation,
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created in the `base temporary directory`_.
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``tmpdir`` is a `py.path.local`_ object which offers ``os.path`` methods
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and more. Here is an example test usage::
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# content of test_tmpdir.py
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import os
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def test_create_file(tmpdir):
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p = tmpdir.mkdir("sub").join("hello.txt")
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p.write("content")
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assert p.read() == "content"
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assert len(tmpdir.listdir()) == 1
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assert 0
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Running this would result in a passed test except for the last
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``assert 0`` line which we use to look at values::
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$ pytest test_tmpdir.py
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=========================== test session starts ============================
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platform linux -- Python 3.x.y, pytest-3.x.y, py-1.x.y, pluggy-0.x.y
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rootdir: $REGENDOC_TMPDIR, inifile:
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collected 1 item
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test_tmpdir.py F [100%]
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================================= FAILURES =================================
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_____________________________ test_create_file _____________________________
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tmpdir = local('PYTEST_TMPDIR/test_create_file0')
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def test_create_file(tmpdir):
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p = tmpdir.mkdir("sub").join("hello.txt")
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p.write("content")
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assert p.read() == "content"
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assert len(tmpdir.listdir()) == 1
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> assert 0
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E assert 0
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test_tmpdir.py:7: AssertionError
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========================= 1 failed in 0.12 seconds =========================
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The 'tmpdir_factory' fixture
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----------------------------
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.. versionadded:: 2.8
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The ``tmpdir_factory`` is a session-scoped fixture which can be used
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to create arbitrary temporary directories from any other fixture or test.
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For example, suppose your test suite needs a large image on disk, which is
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generated procedurally. Instead of computing the same image for each test
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that uses it into its own ``tmpdir``, you can generate it once per-session
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to save time:
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.. code-block:: python
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# contents of conftest.py
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import pytest
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@pytest.fixture(scope='session')
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def image_file(tmpdir_factory):
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img = compute_expensive_image()
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fn = tmpdir_factory.mktemp('data').join('img.png')
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img.save(str(fn))
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return fn
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# contents of test_image.py
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def test_histogram(image_file):
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img = load_image(image_file)
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# compute and test histogram
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``tmpdir_factory`` instances have the following methods:
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.. currentmodule:: _pytest.tmpdir
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.. automethod:: TempdirFactory.mktemp
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.. automethod:: TempdirFactory.getbasetemp
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.. _`base temporary directory`:
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The default base temporary directory
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-----------------------------------------------
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Temporary directories are by default created as sub-directories of
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the system temporary directory. The base name will be ``pytest-NUM`` where
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``NUM`` will be incremented with each test run. Moreover, entries older
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than 3 temporary directories will be removed.
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You can override the default temporary directory setting like this::
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pytest --basetemp=mydir
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When distributing tests on the local machine, ``pytest`` takes care to
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configure a basetemp directory for the sub processes such that all temporary
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data lands below a single per-test run basetemp directory.
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.. _`py.path.local`: https://py.readthedocs.io/en/latest/path.html
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