def test_error_displayed_when_chdir_fails(errstream):
chdir = mock.Mock()
chdir.side_effect = OSError("FAILED")
handler = app.ChangeDirHandler(err=errstream, chdir=chdir)
handler.run(['.cd', 'foo'], None)
assert 'FAILED' in errstream.getvalue()
def test_cd_handler_can_chdir():
chdir = mock.Mock()
handler = app.ChangeDirHandler(chdir=chdir)
handler.run(['.cd', 'foo/bar'], None)
assert chdir.call_args == mock.call('foo/bar')
def test_chdir_syntax_error_prints_err_msg(errstream):
chdir = mock.Mock()
handler = app.ChangeDirHandler(err=errstream, chdir=chdir)
handler.run(['.cd'], None)
assert 'invalid syntax' in errstream.getvalue()
assert not chdir.called