default) then a `MagicMock` will be created for you, with the API limited
to methods or attributes available on standard file handles.
- `read_data` is a string for the `read` method of the file handle to return.
- This is an empty string by default.
+ `read_data` is a string for the `read`, `readline`, and `readlines` methods
+ of the file handle to return. Calls to those methods will take data from
+ `read_data` until it is depleted. The mock of these methods is pretty
+ simplistic. If you need more control over the data that you are feeding to
+ the tested code you will need to customize this mock for yourself.
+ `read_data` is an empty string by default.
Using `open` as a context manager is a great way to ensure your file handles
are closed properly and is becoming common::
return result
ret_val = effect(*args, **kwargs)
- if ret_val is DEFAULT:
- ret_val = self.return_value
if (self._mock_wraps is not None and
self._mock_return_value is DEFAULT):
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
+ data_as_list = ['{}\n'.format(l) for l in read_data.split('\n')]
+
+ if data_as_list[-1] == '\n':
+ # 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]
+ 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
def mock_open(mock=None, read_data=''):
"""
default) then a `MagicMock` will be created for you, with the API limited
to methods or attributes available on standard file handles.
- `read_data` is a string for the `read` method of the file handle to return.
- This is an empty string by default.
+ `read_data` is a string for the `read` methoddline`, and `readlines` of the
+ file handle to return. This is an empty string by default.
"""
+ def _readlines_side_effect(*args, **kwargs):
+ if handle.readlines.return_value is not None:
+ return handle.readlines.return_value
+ return list(_data)
+
+ def _read_side_effect(*args, **kwargs):
+ if handle.read.return_value is not None:
+ return handle.read.return_value
+ return ''.join(_data)
+
+ def _readline_side_effect():
+ if handle.readline.return_value is not None:
+ while True:
+ yield handle.readline.return_value
+ for line in _data:
+ yield line
+
+
global file_spec
if file_spec is None:
import _io
mock = MagicMock(name='open', spec=open)
handle = MagicMock(spec=file_spec)
- handle.write.return_value = None
handle.__enter__.return_value = handle
- handle.read.return_value = read_data
+
+ _data = _iterate_read_data(read_data)
+
+ handle.write.return_value = None
+ handle.read.return_value = None
+ handle.readline.return_value = None
+ handle.readlines.return_value = None
+
+ handle.read.side_effect = _read_side_effect
+ handle.readline.side_effect = _readline_side_effect()
+ handle.readlines.side_effect = _readlines_side_effect
mock.return_value = handle
return mock
self.assertEqual(result, 'foo')
+ def test_readline_data(self):
+ # Check that readline will return all the lines from the fake file
+ mock = mock_open(read_data='foo\nbar\nbaz\n')
+ with patch('%s.open' % __name__, mock, create=True):
+ h = open('bar')
+ line1 = h.readline()
+ line2 = h.readline()
+ line3 = h.readline()
+ self.assertEqual(line1, 'foo\n')
+ self.assertEqual(line2, 'bar\n')
+ self.assertEqual(line3, 'baz\n')
+
+ # Check that we properly emulate a file that doesn't end in a newline
+ mock = mock_open(read_data='foo')
+ with patch('%s.open' % __name__, mock, create=True):
+ h = open('bar')
+ result = h.readline()
+ self.assertEqual(result, 'foo')
+
+
+ def test_readlines_data(self):
+ # Test that emulating a file that ends in a newline character works
+ mock = mock_open(read_data='foo\nbar\nbaz\n')
+ with patch('%s.open' % __name__, mock, create=True):
+ h = open('bar')
+ result = h.readlines()
+ self.assertEqual(result, ['foo\n', 'bar\n', 'baz\n'])
+
+ # Test that files without a final newline will also be correctly
+ # emulated
+ mock = mock_open(read_data='foo\nbar\nbaz')
+ with patch('%s.open' % __name__, mock, create=True):
+ h = open('bar')
+ result = h.readlines()
+
+ self.assertEqual(result, ['foo\n', 'bar\n', 'baz'])
+
+
+ def test_mock_open_read_with_argument(self):
+ # At one point calling read with an argument was broken
+ # 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)
+
+
+ def test_interleaved_reads(self):
+ # Test that calling read, readline, and readlines pulls data
+ # sequentially from the data we preload with
+ mock = mock_open(read_data='foo\nbar\nbaz\n')
+ with patch('%s.open' % __name__, mock, create=True):
+ h = open('bar')
+ line1 = h.readline()
+ rest = h.readlines()
+ self.assertEqual(line1, 'foo\n')
+ self.assertEqual(rest, ['bar\n', 'baz\n'])
+
+ mock = mock_open(read_data='foo\nbar\nbaz\n')
+ with patch('%s.open' % __name__, mock, create=True):
+ h = open('bar')
+ line1 = h.readline()
+ rest = h.read()
+ self.assertEqual(line1, 'foo\n')
+ self.assertEqual(rest, 'bar\nbaz\n')
+
+
+ def test_overriding_return_values(self):
+ mock = mock_open(read_data='foo')
+ handle = mock()
+
+ handle.read.return_value = 'bar'
+ handle.readline.return_value = 'bar'
+ handle.readlines.return_value = ['bar']
+
+ self.assertEqual(handle.read(), 'bar')
+ self.assertEqual(handle.readline(), 'bar')
+ self.assertEqual(handle.readlines(), ['bar'])
+
+ # call repeatedly to check that a StopIteration is not propagated
+ self.assertEqual(handle.readline(), 'bar')
+ self.assertEqual(handle.readline(), 'bar')
+
+
if __name__ == '__main__':
unittest.main()
Library
-------
+- Issue #17467: add readline and readlines support to mock_open in
+ unittest.mock.
+
- Issue #17192: Update the ctypes module's libffi to v3.0.13. This
specifically addresses a stack misalignment issue on x86 and issues on
some more recent platforms.
projects / python / commitdiff