bpo-31855: unittest.mock.mock_open() results now respects the argument of read([size]) (GH-11521)

unittest.mock.mock_open() results now respects the argument of read([size])

Co-Authored-By: remilapeyre <remi.lapeyre@henki.fr>
This commit is contained in:
Rémi Lapeyre 2019-05-07 12:48:36 +02:00 committed by Chris Withers
parent ad4ed87241
commit 11a8832c98
3 changed files with 21 additions and 25 deletions

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@ -25,6 +25,7 @@ __all__ = (
__version__ = '1.0'
import io
import inspect
import pprint
import sys
@ -2318,25 +2319,12 @@ MethodWrapperTypes = (
file_spec = None
def _iterate_read_data(read_data):
# Helper for mock_open:
# Retrieve lines from read_data via a generator so that separate calls to
# readline, read, and readlines are properly interleaved
sep = b'\n' if isinstance(read_data, bytes) else '\n'
data_as_list = [l + sep for l in read_data.split(sep)]
if data_as_list[-1] == sep:
# If the last line ended in a newline, the list comprehension will have an
# extra entry that's just a newline. Remove this.
data_as_list = data_as_list[:-1]
def _to_stream(read_data):
if isinstance(read_data, bytes):
return io.BytesIO(read_data)
else:
# If there wasn't an extra newline by itself, then the file being
# emulated doesn't have a newline to end the last line remove the
# newline that our naive format() added
data_as_list[-1] = data_as_list[-1][:-1]
for line in data_as_list:
yield line
return io.StringIO(read_data)
def mock_open(mock=None, read_data=''):
@ -2351,20 +2339,23 @@ def mock_open(mock=None, read_data=''):
`read_data` is a string for the `read`, `readline` and `readlines` of the
file handle to return. This is an empty string by default.
"""
_read_data = _to_stream(read_data)
_state = [_read_data, None]
def _readlines_side_effect(*args, **kwargs):
if handle.readlines.return_value is not None:
return handle.readlines.return_value
return list(_state[0])
return _state[0].readlines(*args, **kwargs)
def _read_side_effect(*args, **kwargs):
if handle.read.return_value is not None:
return handle.read.return_value
return type(read_data)().join(_state[0])
return _state[0].read(*args, **kwargs)
def _readline_side_effect():
def _readline_side_effect(*args, **kwargs):
yield from _iter_side_effect()
while True:
yield type(read_data)()
yield _state[0].readline(*args, **kwargs)
def _iter_side_effect():
if handle.readline.return_value is not None:
@ -2384,8 +2375,6 @@ def mock_open(mock=None, read_data=''):
handle = MagicMock(spec=file_spec)
handle.__enter__.return_value = handle
_state = [_iterate_read_data(read_data), None]
handle.write.return_value = None
handle.read.return_value = None
handle.readline.return_value = None
@ -2398,7 +2387,7 @@ def mock_open(mock=None, read_data=''):
handle.__iter__.side_effect = _iter_side_effect
def reset_data(*args, **kwargs):
_state[0] = _iterate_read_data(read_data)
_state[0] = _to_stream(read_data)
if handle.readline.side_effect == _state[1]:
# Only reset the side effect if the user hasn't overridden it.
_state[1] = _readline_side_effect()

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@ -283,7 +283,12 @@ class TestMockOpen(unittest.TestCase):
# for mocks returned by mock_open
some_data = 'foo\nbar\nbaz'
mock = mock_open(read_data=some_data)
self.assertEqual(mock().read(10), some_data)
self.assertEqual(mock().read(10), some_data[:10])
self.assertEqual(mock().read(10), some_data[:10])
f = mock()
self.assertEqual(f.read(10), some_data[:10])
self.assertEqual(f.read(10), some_data[10:])
def test_interleaved_reads(self):

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@ -0,0 +1,2 @@
:func:`unittest.mock.mock_open` results now respects the argument of read([size]).
Patch contributed by Rémi Lapeyre.