def test_warp_dst_crs_empty_string(runner, tmpdir):

    infile = 'tests/data/RGB.byte.tif'
    outfile = str(tmpdir.mkdir('empty_warp_dst_crs.tif').join('test.tif'))

    result = runner.invoke(warp.warp, [
        infile,
        outfile,
        '--dst-crs', ''])

    assert result.exit_code != 0
    assert 'empty or invalid' in result.output
`$ rio warp --dst-crs ''` used to perform a falsey check that would treat
dataset/ETHPy150Open mapbox/rasterio/tests/test_rio_warp.py/test_warp_dst_crs_empty_string