mapnik/tests/python_tests/layer_modification_test.py

#!/usr/bin/env python

import os
from nose.tools import *
from utilities import execution_path, run_all
import mapnik

def setup():
    # All of the paths used are relative, if we run the tests
    # from another directory we need to chdir()
    os.chdir(execution_path('.'))

def test_adding_datasource_to_layer():
    map_string = '''<?xml version="1.0" encoding="utf-8"?>
<Map>

    <Layer name="world_borders">
        <StyleName>world_borders_style</StyleName>
        <StyleName>point_style</StyleName>
        <!-- leave datasource empty -->
        <!--
        <Datasource>
            <Parameter name="file">../data/shp/world_merc.shp</Parameter>
            <Parameter name="type">shape</Parameter>
        </Datasource>
        -->
    </Layer>

</Map>
'''
    if 'shape' not in mapnik.DatasourceCache.plugin_names():
        print "skipping test_adding_datasource_to_layer because \"shape\" plugin is not available"
        return

    m = mapnik.Map(256, 256)

    mapnik.load_map_from_string(m, map_string)

    # validate it loaded fine
    eq_(m.layers[0].styles[0], 'world_borders_style')
    eq_(m.layers[0].styles[1], 'point_style')
    eq_(len(m.layers), 1)

    # also assign a variable reference to that layer
    # below we will test that this variable references
    # the same object that is attached to the map
    lyr = m.layers[0]

    # ensure that there was no datasource for the layer...
    eq_(m.layers[0].datasource, None)
    eq_(lyr.datasource, None)

    # also note that since the srs was black it defaulted to wgs84
    eq_(m.layers[0].srs, '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs')
    eq_(lyr.srs, '+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs')

    # now add a datasource one...
    ds = mapnik.Shapefile(file='../data/shp/world_merc.shp')
    m.layers[0].datasource = ds

    # now ensure it is attached
    eq_(m.layers[0].datasource.describe()['name'], "shape")
    eq_(lyr.datasource.describe()['name'], "shape")

    # and since we have now added a shapefile in spherical mercator, adjust the projection
    lyr.srs = '+proj=merc +lon_0=0 +lat_ts=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs'

    # test that assignment
    eq_(m.layers[0].srs, '+proj=merc +lon_0=0 +lat_ts=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs')
    eq_(lyr.srs, '+proj=merc +lon_0=0 +lat_ts=0 +x_0=0 +y_0=0 +ellps=WGS84 +datum=WGS84 +units=m +no_defs')

if __name__ == "__main__":
    setup()
    exit(run_all(eval(x) for x in dir() if x.startswith("test_")))