def diff_image(self, expected_contents, actual_contents, tolerance):
if tolerance != self._tolerance or (
self._process and self._process.has_available_stdout()):
self.stop()
try:
assert (expected_contents)
assert (actual_contents)
assert (tolerance is not None)
if not self._process:
self._start(tolerance)
# Note that although we are handed 'old', 'new', ImageDiff wants 'new', 'old'.
buffer = BytesIO()
buffer.write(
string_utils.encode('Content-Length: {}\n'.format(
len(actual_contents))))
buffer.write(actual_contents)
buffer.write(
string_utils.encode('Content-Length: {}\n'.format(
len(expected_contents))))
buffer.write(expected_contents)
self._process.write(buffer.getvalue())
return self._read()
except IOError as exception:
return (None, 0,
"Failed to compute an image diff: %s" % str(exception))
def test_bytesio(self):
stream = BytesIO()
stream.write(b'bytes data')
self.assertEqual(stream.getvalue(), b'bytes data')