def test_topojson_init():
        # topojson tests/data/json/escaped.geojson -o tests/data/topojson/escaped.topojson --properties
        # topojson version 1.4.2
        ds = mapnik.Datasource(
            type='topojson',
            file='../data/topojson/escaped.topojson')
        e = ds.envelope()
        assert_almost_equal(e.minx, -81.705583, places=7)
        assert_almost_equal(e.miny, 41.480573, places=6)
        assert_almost_equal(e.maxx, -81.705583, places=5)
        assert_almost_equal(e.maxy, 41.480573, places=3)