"""
Verify evaluation of BIND expressions of different types. See
<http://www.w3.org/TR/sparql11-query/#rExpression>.
"""
from rdflib import Graph, URIRef, Literal, Variable


def test_bind():
    base = "http://example.org/"
    g = Graph()
    g.add((URIRef(
        base + "thing"), URIRef(base + "ns#comment"), Literal("anything")))

    def check(expr, var, obj):
        r = g.query("""
                prefix : <http://example.org/ns#>
                select * where { ?s ?p ?o . %s } """ % expr)
        assert r.bindings[0][Variable(var)] == obj

    yield (check, 'bind("thing" as ?name)', 'name', Literal("thing"))

    yield (check, 'bind(<http://example.org/other> as ?other)', 'other',
           URIRef("http://example.org/other"))

    yield (check, "bind(:Thing as ?type)", 'type',
           URIRef("http://example.org/ns#Thing"))