else:

self.fail("Expected OSError: %s" % desired_exception)

# We mock the __del__ method for Popen in the next two tests

# because it does cleanup based on the pid returned by fork_exec

# along with issuing a resource warning if it still exists. Since

# we don't actually spawn a process in these tests we can forego

# the destructor. An alternative would be to set _child_created to

# False before the destructor is called but there is no easy way

# to do that

class PopenNoDestructor(subprocess.Popen):

def __del__(self):

pass

@mock.patch("subprocess._posixsubprocess.fork_exec")

def test_exception_errpipe_normal(self, fork_exec):

"""Test error passing done through errpipe_write in the good case"""

def proper_error(*args):

errpipe_write = args[13]

# Write the hex for the error code EISDIR: 'is a directory'

err_code = '{:x}'.format(errno.EISDIR).encode()

os.write(errpipe_write, b"OSError:" + err_code + b":")

return 0

fork_exec.side_effect = proper_error

with self.assertRaises(IsADirectoryError):

self.PopenNoDestructor(["non_existent_command"])

@mock.patch("subprocess._posixsubprocess.fork_exec")

def test_exception_errpipe_bad_data(self, fork_exec):

"""Test error passing done through errpipe_write where its not

in the expected format"""

error_data = b"\xFF\x00\xDE\xAD"

def bad_error(*args):

errpipe_write = args[13]

# Anything can be in the pipe, no assumptions should

# be made about its encoding, so we'll write some

# arbitrary hex bytes to test it out

os.write(errpipe_write, error_data)

return 0

fork_exec.side_effect = bad_error

with self.assertRaises(subprocess.SubprocessError) as e:

self.PopenNoDestructor(["non_existent_command"])

self.assertIn(repr(error_data), str(e.exception))

def test_restore_signals(self):

# Code coverage for both values of restore_signals to make sure it

# at least does not blow up.