Add docstring and use tmp_path in tests

Related to #10114

src/_pytest/atomic_writes.py

@@ -1,5 +1,10 @@
+"""
+Module copied over from https://github.com/untitaker/python-atomicwrites, which has become
+unmaintained.
+
+Since then, we have made changes to simplify the code, focusing on pytest's use-case.
+"""
 import contextlib
-import io
 import os
 import sys
 import tempfile
@@ -15,7 +20,7 @@ try:
 except ImportError:
     fspath = None
 
-__version__ = '1.4.1'
+__version__ = "1.4.1"
 
 
 PY2 = sys.version_info[0] == 2
@@ -35,8 +40,9 @@ DEFAULT_MODE = "wb" if PY2 else "w"
 _proper_fsync = os.fsync
 
 
-if sys.platform != 'win32':
+if sys.platform != "win32":
-    if hasattr(fcntl, 'F_FULLFSYNC'):
+    if hasattr(fcntl, "F_FULLFSYNC"):
+
         def _proper_fsync(fd):
             # https://lists.apple.com/archives/darwin-dev/2005/Feb/msg00072.html
             # https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man2/fsync.2.html
@@ -64,6 +70,7 @@ if sys.platform != 'win32':
         _sync_directory(dst_dir)
         if src_dir != dst_dir:
             _sync_directory(src_dir)
+
 else:
     from ctypes import windll, WinError
 
@@ -76,43 +83,47 @@ else:
             raise WinError()
 
     def _replace_atomic(src, dst):
-        _handle_errors(windll.kernel32.MoveFileExW(
+        _handle_errors(
-            _path_to_unicode(src), _path_to_unicode(dst),
+            windll.kernel32.MoveFileExW(
-            _windows_default_flags | _MOVEFILE_REPLACE_EXISTING
+                _path_to_unicode(src),
-        ))
+                _path_to_unicode(dst),
+                _windows_default_flags | _MOVEFILE_REPLACE_EXISTING,
+            )
+        )
 
     def _move_atomic(src, dst):
-        _handle_errors(windll.kernel32.MoveFileExW(
+        _handle_errors(
-            _path_to_unicode(src), _path_to_unicode(dst),
+            windll.kernel32.MoveFileExW(
-            _windows_default_flags
+                _path_to_unicode(src), _path_to_unicode(dst), _windows_default_flags
-        ))
+            )
+        )
 
 
 def replace_atomic(src, dst):
-    '''
+    """
     Move ``src`` to ``dst``. If ``dst`` exists, it will be silently
     overwritten.
 
     Both paths must reside on the same filesystem for the operation to be
     atomic.
-    '''
+    """
     return _replace_atomic(src, dst)
 
 
 def move_atomic(src, dst):
-    '''
+    """
     Move ``src`` to ``dst``. There might a timewindow where both filesystem
     entries exist. If ``dst`` already exists, :py:exc:`FileExistsError` will be
     raised.
 
     Both paths must reside on the same filesystem for the operation to be
     atomic.
-    '''
+    """
     return _move_atomic(src, dst)
 
 
-class AtomicWriter(object):
+class AtomicWriter:
-    '''
+    """
     A helper class for performing atomic writes. Usage::
 
         with AtomicWriter(path).open() as f:
@@ -130,21 +141,20 @@ class AtomicWriter(object):
 
     If you need further control over the exact behavior, you are encouraged to
     subclass.
-    '''
+    """
 
-    def __init__(self, path, mode=DEFAULT_MODE, overwrite=False,
+    def __init__(self, path, mode=DEFAULT_MODE, overwrite=False, **open_kwargs):
-                 **open_kwargs):
+        if "a" in mode:
-        if 'a' in mode:
             raise ValueError(
-                'Appending to an existing file is not supported, because that '
+                "Appending to an existing file is not supported, because that "
-                'would involve an expensive `copy`-operation to a temporary '
+                "would involve an expensive `copy`-operation to a temporary "
-                'file. Open the file in normal `w`-mode and copy explicitly '
+                "file. Open the file in normal `w`-mode and copy explicitly "
-                'if that\'s what you\'re after.'
+                "if that's what you're after."
             )
-        if 'x' in mode:
+        if "x" in mode:
-            raise ValueError('Use the `overwrite`-parameter instead.')
+            raise ValueError("Use the `overwrite`-parameter instead.")
-        if 'w' not in mode:
+        if "w" not in mode:
-            raise ValueError('AtomicWriters can only be written to.')
+            raise ValueError("AtomicWriters can only be written to.")
 
         # Attempt to convert `path` to `str` or `bytes`
         if fspath is not None:
@@ -156,9 +166,9 @@ class AtomicWriter(object):
         self._open_kwargs = open_kwargs
 
     def open(self):
-        '''
+        """
         Open the temporary file.
-        '''
+        """
         return self._open(self.get_fileobject)
 
     @contextlib.contextmanager
@@ -178,41 +188,41 @@ class AtomicWriter(object):
                 except Exception:
                     pass
 
-    def get_fileobject(self, suffix="", prefix=tempfile.gettempprefix(),
+    def get_fileobject(
-                       dir=None, **kwargs):
+        self, suffix="", prefix=tempfile.gettempprefix(), dir=None, **kwargs
-        '''Return the temporary file to use.'''
+    ):
+        """Return the temporary file to use."""
         if dir is None:
             dir = os.path.normpath(os.path.dirname(self._path))
-        descriptor, name = tempfile.mkstemp(suffix=suffix, prefix=prefix,
+        descriptor, name = tempfile.mkstemp(suffix=suffix, prefix=prefix, dir=dir)
-                                            dir=dir)
         # io.open() will take either the descriptor or the name, but we need
         # the name later for commit()/replace_atomic() and couldn't find a way
         # to get the filename from the descriptor.
         os.close(descriptor)
-        kwargs['mode'] = self._mode
+        kwargs["mode"] = self._mode
-        kwargs['file'] = name
+        kwargs["file"] = name
-        return io.open(**kwargs)
+        return open(**kwargs)
 
     def sync(self, f):
-        '''responsible for clearing as many file caches as possible before
+        """responsible for clearing as many file caches as possible before
-        commit'''
+        commit"""
         f.flush()
         _proper_fsync(f.fileno())
 
     def commit(self, f):
-        '''Move the temporary file to the target location.'''
+        """Move the temporary file to the target location."""
         if self._overwrite:
             replace_atomic(f.name, self._path)
         else:
             move_atomic(f.name, self._path)
 
     def rollback(self, f):
-        '''Clean up all temporary resources.'''
+        """Clean up all temporary resources."""
         os.unlink(f.name)
 
 
 def atomic_write(path, writer_cls=AtomicWriter, **cls_kwargs):
-    '''
+    """
     Simple atomic writes. This wraps :py:class:`AtomicWriter`::
 
         with atomic_write(path) as f:
@@ -225,5 +235,5 @@ def atomic_write(path, writer_cls=AtomicWriter, **cls_kwargs):
 
     Additional keyword arguments are passed to the writer class. See
     :py:class:`AtomicWriter`.
-    '''
+    """
     return writer_cls(path, **cls_kwargs).open()

testing/test_atomic_writes.py

@@ -1,63 +1,69 @@
+"""
+Module copied over from https://github.com/untitaker/python-atomicwrites, which has become
+unmaintained.
+
+Since then, we have made changes to simplify the code, focusing on pytest's use-case.
+"""
 import errno
 import os
-
+from pathlib import Path
-from atomicwrites import atomic_write
 
 import pytest
+from _pytest.atomic_writes import atomic_write
 
 
-def test_atomic_write(tmpdir):
+def test_atomic_write(tmp_path: Path) -> None:
-    fname = tmpdir.join('ha')
+    fname = tmp_path.joinpath("ha")
     for i in range(2):
         with atomic_write(str(fname), overwrite=True) as f:
-            f.write('hoho')
+            f.write("hoho")
 
     with pytest.raises(OSError) as excinfo:
         with atomic_write(str(fname), overwrite=False) as f:
-            f.write('haha')
+            f.write("haha")
 
     assert excinfo.value.errno == errno.EEXIST
 
-    assert fname.read() == 'hoho'
+    assert fname.read_text() == "hoho"
-    assert len(tmpdir.listdir()) == 1
+    assert len(list(tmp_path.iterdir())) == 1
 
 
-def test_teardown(tmpdir):
+def test_teardown(tmp_path: Path) -> None:
-    fname = tmpdir.join('ha')
+    fname = tmp_path.joinpath("ha")
     with pytest.raises(AssertionError):
         with atomic_write(str(fname), overwrite=True):
             assert False
 
-    assert not tmpdir.listdir()
+    assert not list(tmp_path.iterdir())
 
 
-def test_replace_simultaneously_created_file(tmpdir):
+def test_replace_simultaneously_created_file(tmp_path: Path) -> None:
-    fname = tmpdir.join('ha')
+    fname = tmp_path.joinpath("ha")
     with atomic_write(str(fname), overwrite=True) as f:
-        f.write('hoho')
+        f.write("hoho")
-        fname.write('harhar')
+        fname.write_text("harhar")
-        assert fname.read() == 'harhar'
+        assert fname.read_text() == "harhar"
-    assert fname.read() == 'hoho'
+    assert fname.read_text() == "hoho"
-    assert len(tmpdir.listdir()) == 1
+    assert len(list(tmp_path.iterdir())) == 1
 
 
-def test_dont_remove_simultaneously_created_file(tmpdir):
+def test_dont_remove_simultaneously_created_file(tmp_path: Path) -> None:
-    fname = tmpdir.join('ha')
+    fname = tmp_path.joinpath("ha")
     with pytest.raises(OSError) as excinfo:
         with atomic_write(str(fname), overwrite=False) as f:
-            f.write('hoho')
+            f.write("hoho")
-            fname.write('harhar')
+            fname.write_text("harhar")
-            assert fname.read() == 'harhar'
+            assert fname.read_text() == "harhar"
 
     assert excinfo.value.errno == errno.EEXIST
-    assert fname.read() == 'harhar'
+    assert fname.read_text() == "harhar"
-    assert len(tmpdir.listdir()) == 1
+    assert len(list(tmp_path.iterdir())) == 1
 
 
 # Verify that nested exceptions during rollback do not overwrite the initial
 # exception that triggered a rollback.
-def test_open_reraise(tmpdir):
+def test_open_reraise(tmp_path: Path) -> None:
-    fname = tmpdir.join('ha')
+    fname = tmp_path.joinpath("ha")
     with pytest.raises(AssertionError):
         aw = atomic_write(str(fname), overwrite=False)
         with aw:
@@ -70,22 +76,23 @@ def test_open_reraise(tmpdir):
             assert False, "Intentional failure for testing purposes"
 
 
-def test_atomic_write_in_pwd(tmpdir):
+def test_atomic_write_in_pwd(tmp_path: Path) -> None:
     orig_curdir = os.getcwd()
     try:
-        os.chdir(str(tmpdir))
+        os.chdir(str(tmp_path))
-        fname = 'ha'
+        fname = "ha"
         for i in range(2):
             with atomic_write(str(fname), overwrite=True) as f:
-                f.write('hoho')
+                f.write("hoho")
 
         with pytest.raises(OSError) as excinfo:
             with atomic_write(str(fname), overwrite=False) as f:
-                f.write('haha')
+                f.write("haha")
 
         assert excinfo.value.errno == errno.EEXIST
 
-        assert open(fname).read() == 'hoho'
+        with open(fname) as f:
-        assert len(tmpdir.listdir()) == 1
+            assert f.read() == "hoho"
+        assert len(list(tmp_path.iterdir())) == 1
     finally:
         os.chdir(orig_curdir)