Python doctest file to test generation of a WPS request from input arguments.
The specific request involves a FeatureWeightedGridStatisticsAlgorithm process over a multi-polygon feature.

Import python modules

    >>> from __future__ import (absolute_import, division, print_function)
    >>> from tests.utils import resource_file, compare_xml
    >>> from owslib.wps import GMLMultiPolygonFeatureCollection, WebProcessingService, WPSExecution
    >>> from owslib.etree import etree

Supply process input arguments

    >>> polygon = [(-102.8184, 39.5273), (-102.8184, 37.418), (-101.2363, 37.418), (-101.2363, 39.5273), (-102.8184, 39.5273)]
    >>> featureCollection = GMLMultiPolygonFeatureCollection( [polygon] )
    >>> processid = 'gov.usgs.cida.gdp.wps.algorithm.FeatureWeightedGridStatisticsAlgorithm'
    >>> inputs = [ ("FEATURE_ATTRIBUTE_NAME","the_geom"),
    ...            ("DATASET_URI", "dods://igsarm-cida-thredds1.er.usgs.gov:8080/thredds/dodsC/dcp/conus_grid.w_meta.ncml"),
    ...            ("DATASET_ID", "ccsm3_a1b_tmax"),
    ...            ("TIME_START","1960-01-01T00:00:00.000Z"),
    ...            ("TIME_END","1960-12-31T00:00:00.000Z"),
    ...            ("REQUIRE_FULL_COVERAGE","true"),
    ...            ("DELIMITER","COMMA"),
    ...            ("STATISTICS","MEAN"),
    ...            ("STATISTICS","MINIMUM"),
    ...            ("STATISTICS","MAXIMUM"),
    ...            ("STATISTICS","WEIGHT_SUM"),
    ...            ("STATISTICS","VARIANCE"),
    ...            ("STATISTICS","STD_DEV"),
    ...            ("STATISTICS","COUNT"),
    ...            ("GROUP_BY","STATISTIC"),
    ...            ("SUMMARIZE_TIMESTEP","false"),
    ...            ("SUMMARIZE_FEATURE_ATTRIBUTE","false"),
    ...            ("FEATURE_COLLECTION", featureCollection)
    ...           ]
    >>> output = "OUTPUT"

    # build XML request for WPS process execution
    >>> execution = WPSExecution()
    >>> requestElement = execution.buildRequest(processid, inputs, output=output)
    >>> request = etree.tostring( requestElement )

Compare to cached XML request

    >>> _request = open(resource_file('wps_USGSExecuteRequest3.xml'), 'rb').read()
    >>> compare_xml(request, _request)
    True
    
