path: root/test/query/test_validator.py

"""

Part of the tagit test suite.
A copy of the license is provided with the project.
Author: Matthias Baumgartner, 2022
"""
# imports
import unittest

# bsfs imports
from bsfs import schema as _schema
from bsfs.namespace import ns
from bsfs.query import ast
from bsfs.utils import errors

# objects to test
from bsfs.query.validator import Filter, Fetch


## code ##

class TestFilter(unittest.TestCase):
    def setUp(self):
        self.schema = _schema.from_string('''
            prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
            prefix xsd: <http://www.w3.org/2001/XMLSchema#>

            prefix bsfs: <http://bsfs.ai/schema/>
            prefix bse: <http://bsfs.ai/schema/Entity#>

            bsfs:Entity rdfs:subClassOf bsfs:Node .
            bsfs:URI rdfs:subClassOf bsfs:Literal .

            bsfs:Tag rdfs:subClassOf bsfs:Node .
            xsd:string rdfs:subClassOf bsfs:Literal .
            bsfs:Number rdfs:subClassOf bsfs:Literal .
            bsfs:Array rdfs:subClassOf bsfs:Literal .
            bsfs:Feature rdfs:subClassOf bsfs:Array .
            xsd:integer rdfs:subClassOf bsfs:Number .

            bsfs:Colors rdfs:subClassOf bsfs:Feature ;
                bsfs:dimension "5"^^xsd:integer ;
                bsfs:dtype bsfs:f32 .

            bse:color rdfs:subClassOf bsfs:Predicate ;
                rdfs:domain bsfs:Node ;
                rdfs:range bsfs:Colors ;
                bsfs:unique "true"^^xsd:boolean .

            bse:comment rdfs:subClassOf bsfs:Predicate ;
                rdfs:domain bsfs:Node ;
                rdfs:range xsd:string ;
                bsfs:unique "false"^^xsd:boolean .

            bse:filesize rdfs:subClassOf bsfs:Predicate ;
                rdfs:domain bsfs:Entity ;
                rdfs:range xsd:integer ;
                bsfs:unique "true"^^xsd:boolean .

            bse:tag rdfs:subClassOf bsfs:Predicate ;
                rdfs:domain bsfs:Entity ;
                rdfs:range bsfs:Tag ;
                bsfs:unique "false"^^xsd:boolean .

            bse:label rdfs:subClassOf bsfs:Predicate ;
                rdfs:domain bsfs:Tag ;
                rdfs:range xsd:string ;
                bsfs:unique "true"^^xsd:boolean .

            bse:buddy rdfs:subClassOf bsfs:Predicate ;
                rdfs:domain bsfs:Entity ;
                rdfs:range bsfs:Node ;
                bsfs:unique "false"^^xsd:boolean .

            ''')
        self.validate = Filter(self.schema)

    def test_call(self):
        # root_type must be a _schema.Node
        self.assertRaises(TypeError, self.validate, 1234, None)
        self.assertRaises(TypeError, self.validate, '1234', None)
        self.assertRaises(TypeError, self.validate, self.schema.literal(ns.bsfs.URI), None)
        # root_type must exist in the schema
        self.assertRaises(errors.ConsistencyError, self.validate, self.schema.node(ns.bsfs.Node).child(ns.bsfs.Image), None)
        self.assertRaises(errors.ConsistencyError, self.validate, self.schema.node(ns.bsfs.Entity).child(ns.bsfs.Image), None)
        # valid query returns true
        self.assertTrue(self.validate(self.schema.node(ns.bsfs.Entity),
            ast.filter.Any(ast.filter.OneOf(ns.bse.tag, ns.bse.buddy),
                ast.filter.Or(
                    ast.filter.Is('http://example.com/symbol#1234'),
                    ast.filter.All(ns.bse.comment, ast.filter.StartsWith('foo')),
                    ast.filter.And(
                        ast.filter.Has(ns.bse.comment, ast.filter.Or(
                            ast.filter.GreaterThan(5),
                            ast.filter.LessThan(1),
                            )
                        ),
                        ast.filter.Not(ast.filter.Any(ns.bse.comment,
                            ast.filter.Not(ast.filter.Equals('hello world')))),
                    ast.filter.Any(ns.bse.color, ast.filter.Distance([1,2,3,4,5], 3)),
                    )))))
        # invalid paths raise consistency error
        self.assertRaises(errors.ConsistencyError, self.validate, self.schema.node(ns.bsfs.Entity),
            ast.filter.Any(ast.filter.OneOf(ns.bse.tag, ns.bse.buddy),
            ast.filter.Or(
                ast.filter.All(ns.bse.comment, ast.filter.Equals('hello world')),
                ast.filter.All(ns.bse.label, ast.filter.Equals('hello world')), # domain mismatch
                )))

    def test_routing(self):
        self.assertRaises(errors.BackendError, self.validate._parse_filter_expression, ast.filter.FilterExpression(), self.schema.node(ns.bsfs.Node))
        self.assertRaises(errors.BackendError, self.validate._parse_predicate_expression, ast.filter.PredicateExpression())

    def test_predicate(self):
        # predicate must be in the schema
        self.assertRaises(errors.ConsistencyError, self.validate._predicate, ast.filter.Predicate(ns.bse.invalid))
        # predicate must have a range
        self.assertRaises(errors.BackendError, self.validate._predicate, ast.filter.Predicate(ns.bsfs.Predicate))
        # predicate returns domain and range
        self.assertEqual(self.validate._predicate(ast.filter.Predicate(ns.bse.tag)),
            (self.schema.node(ns.bsfs.Entity), self.schema.node(ns.bsfs.Tag)))
        # reverse is applied
        self.assertEqual(self.validate._predicate(ast.filter.Predicate(ns.bse.tag, reverse=True)),
            (self.schema.node(ns.bsfs.Tag), self.schema.node(ns.bsfs.Entity)))

    def test_one_of(self):
        # domains must both be nodes or literals
        self.assertRaises(errors.ConsistencyError, self.validate._one_of, ast.filter.OneOf(ns.bse.tag, ast.filter.Predicate(ns.bse.label, reverse=True)))
        # domains must be related
        self.assertRaises(errors.ConsistencyError, self.validate._one_of, ast.filter.OneOf(ns.bse.tag, ns.bse.label))
        # ranges must both be nodes or literals
        self.assertRaises(errors.ConsistencyError, self.validate._one_of, ast.filter.OneOf(ns.bse.tag, ns.bse.comment))
        # ranges must be related
        self.assertRaises(errors.ConsistencyError, self.validate._one_of, ast.filter.OneOf(ns.bse.tag, ast.filter.Predicate(ns.bse.buddy, reverse=True)))
        # one_of returns most specific domain
        self.assertEqual(self.validate._one_of(ast.filter.OneOf(ns.bse.comment, ns.bse.label)),
            (self.schema.node(ns.bsfs.Tag), self.schema.literal(ns.xsd.string)))
        # one_of returns the most generic range
        self.assertEqual(self.validate._one_of(ast.filter.OneOf(ns.bse.tag, ns.bse.buddy)),
            (self.schema.node(ns.bsfs.Entity), self.schema.node(ns.bsfs.Node)))

    def test_branch(self):
        # type must be a node
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.literal(ns.bsfs.Literal), None)
        # type must be in the schema
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Node).child(ns.bsfs.Invalid), None)
        # predicate is verified
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Entity),
            ast.filter.Any(ns.bsfs.Invalid, ast.filter.Is('http://example.com/entity#1234')))
        # predicate must match the domain
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Node),
            ast.filter.Any(ns.bse.tag, ast.filter.Is('http://example.com/tag#1234')))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Tag),
            ast.filter.Any(ns.bse.tag, ast.filter.Is('http://example.com/tag#1234')))
        # child expression must be valid
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Entity),
            ast.filter.Any(ns.bse.tag, ast.filter.Equals('hello world')))
        # branch accepts valid expressions
        self.assertIsNone(self.validate._branch(self.schema.node(ns.bsfs.Entity),
            ast.filter.Any(ns.bse.tag, ast.filter.Is('http://example.com/entity#1234'))))
        self.assertIsNone(self.validate._branch(self.schema.node(ns.bsfs.Entity),
            ast.filter.All(ns.bse.tag, ast.filter.Is('http://example.com/entity#1234'))))

    def test_agg(self):
        # agg evaluates child expressions
        self.assertRaises(errors.ConsistencyError, self.validate._agg, self.schema.node(ns.bsfs.Entity),
            ast.filter.And(ast.filter.Is('http://example.com/entity#1234'), ast.filter.Equals('hello world')))
        self.assertRaises(errors.ConsistencyError, self.validate._agg, self.schema.literal(ns.xsd.string),
            ast.filter.And(ast.filter.Is('http://example.com/entity#1234'), ast.filter.Equals('hello world')))
        self.assertRaises(errors.ConsistencyError, self.validate._agg, self.schema.node(ns.bsfs.Entity),
            ast.filter.Or(ast.filter.Is('http://example.com/entity#1234'), ast.filter.Equals('hello world')))
        self.assertRaises(errors.ConsistencyError, self.validate._agg, self.schema.literal(ns.xsd.string),
            ast.filter.Or(ast.filter.Is('http://example.com/entity#1234'), ast.filter.Equals('hello world')))
        # agg works on nodes
        self.assertIsNone(self.validate._agg(self.schema.node(ns.bsfs.Entity),
            ast.filter.And(ast.filter.Is('http://example.com/entity#1234'), ast.filter.Is('http://example.com/entity#4321'))))
        self.assertIsNone(self.validate._agg(self.schema.node(ns.bsfs.Entity),
            ast.filter.Or(ast.filter.Is('http://example.com/entity#1234'), ast.filter.Is('http://example.com/entity#4321'))))
        # agg works on literals
        self.assertIsNone(self.validate._agg(self.schema.literal(ns.xsd.string),
            ast.filter.And(ast.filter.Equals('foobar'), ast.filter.Equals('hello world'))))
        self.assertIsNone(self.validate._agg(self.schema.literal(ns.xsd.string),
            ast.filter.Or(ast.filter.Equals('foobar'), ast.filter.Equals('hello world'))))

    def test_not(self):
        # not evaluates child expressions
        self.assertRaises(errors.ConsistencyError, self.validate._not, self.schema.node(ns.bsfs.Entity),
            ast.filter.Not(ast.filter.Equals('hello world')))
        self.assertRaises(errors.ConsistencyError, self.validate._not, self.schema.literal(ns.xsd.string),
            ast.filter.Not(ast.filter.Is('http://example.com/entity#1234')))
        # not works on nodes
        self.assertIsNone(self.validate._not(self.schema.node(ns.bsfs.Entity),
            ast.filter.Not(ast.filter.Is('http://example.com/entity#1234'))))
        # not works on literals
        self.assertIsNone(self.validate._not(self.schema.literal(ns.xsd.string),
            ast.filter.Not(ast.filter.Equals('hello world'))))

    def test_has(self):
        # type must be node
        self.assertRaises(errors.ConsistencyError, self.validate._has, self.schema.literal(ns.bsfs.Literal),
            ast.filter.Has(ns.bse.tag))
        # type must be in the schema
        self.assertRaises(errors.ConsistencyError, self.validate._has, self.schema.node(ns.bsfs.Node).child(ns.bsfs.Invalid),
            ast.filter.Has(ns.bse.tag))
        # has checks predicate
        self.assertRaises(errors.ConsistencyError, self.validate._has, self.schema.node(ns.bsfs.Entity),
            ast.filter.Has(ns.bse.invalid))
        # predicate must match domain
        self.assertRaises(errors.ConsistencyError, self.validate._has, self.schema.node(ns.bsfs.Tag),
            ast.filter.Has(ns.bse.tag))
        # has checks count expression
        self.assertRaises(errors.ConsistencyError, self.validate._has, self.schema.node(ns.bsfs.Entity),
            ast.filter.Has(ns.bse.tag, ast.filter.Is('http://example.com/entity#1234')))
        # has accepts correct expressions
        self.assertIsNone(self.validate._has(self.schema.node(ns.bsfs.Entity), ast.filter.Has(ns.bse.tag, ast.filter.GreaterThan(5))))

    def test_is(self):
        # type must be node
        self.assertRaises(errors.ConsistencyError, self.validate._is, self.schema.literal(ns.bsfs.Literal),
            ast.filter.Is('http://example.com/foo'))
        # type must be in the schema
        self.assertRaises(errors.ConsistencyError, self.validate._is, self.schema.node(ns.bsfs.Node).child(ns.bsfs.Invalid),
            ast.filter.Is('http://example.com/foo'))
        # is accepts correct expressions
        self.assertIsNone(self.validate._is(self.schema.node(ns.bsfs.Entity), ast.filter.Is('http://example.com/entity#1234')))

    def test_value(self):
        # type must be literal
        self.assertRaises(errors.ConsistencyError, self.validate._value, self.schema.node(ns.bsfs.Node),
            ast.filter.Equals('hello world'))
        self.assertRaises(errors.ConsistencyError, self.validate._value, self.schema.node(ns.bsfs.Node),
            ast.filter.Substring('hello world'))
        self.assertRaises(errors.ConsistencyError, self.validate._value, self.schema.node(ns.bsfs.Node),
            ast.filter.StartsWith('hello world'))
        self.assertRaises(errors.ConsistencyError, self.validate._value, self.schema.node(ns.bsfs.Node),
            ast.filter.EndsWith('hello world'))
        # type must be in the schema
        self.assertRaises(errors.ConsistencyError, self.validate._value, self.schema.literal(ns.bsfs.Literal).child(ns.bsfs.Invalid),
            ast.filter.Equals('hello world'))
        self.assertRaises(errors.ConsistencyError, self.validate._value, self.schema.literal(ns.bsfs.Literal).child(ns.bsfs.Invalid),
            ast.filter.Substring('hello world'))
        self.assertRaises(errors.ConsistencyError, self.validate._value, self.schema.literal(ns.bsfs.Literal).child(ns.bsfs.Invalid),
            ast.filter.StartsWith('hello world'))
        self.assertRaises(errors.ConsistencyError, self.validate._value, self.schema.literal(ns.bsfs.Literal).child(ns.bsfs.Invalid),
            ast.filter.EndsWith('hello world'))
        # value accepts correct expressions
        self.assertIsNone(self.validate._value(self.schema.literal(ns.xsd.string), ast.filter.Equals('hello world')))
        self.assertIsNone(self.validate._value(self.schema.literal(ns.xsd.string), ast.filter.Substring('hello world')))
        self.assertIsNone(self.validate._value(self.schema.literal(ns.xsd.string), ast.filter.StartsWith('hello world')))
        self.assertIsNone(self.validate._value(self.schema.literal(ns.xsd.string), ast.filter.EndsWith('hello world')))

    def test_bounded(self):
        # type must be literal
        self.assertRaises(errors.ConsistencyError, self.validate._bounded, self.schema.node(ns.bsfs.Node),
            ast.filter.GreaterThan(0))
        self.assertRaises(errors.ConsistencyError, self.validate._bounded, self.schema.node(ns.bsfs.Node),
            ast.filter.LessThan(0))
        # type must be in the schema
        self.assertRaises(errors.ConsistencyError, self.validate._bounded, self.schema.literal(ns.bsfs.Literal).child(ns.bsfs.Invalid),
            ast.filter.GreaterThan(0))
        self.assertRaises(errors.ConsistencyError, self.validate._bounded, self.schema.literal(ns.bsfs.Literal).child(ns.bsfs.Invalid),
            ast.filter.LessThan(0))
        # type must be a number
        self.assertRaises(errors.ConsistencyError, self.validate._bounded, self.schema.literal(ns.xsd.string),
            ast.filter.LessThan(0))
        # bounded accepts correct expressions
        self.assertIsNone(self.validate._bounded(self.schema.literal(ns.xsd.integer), ast.filter.LessThan(0)))
        self.assertIsNone(self.validate._bounded(self.schema.literal(ns.xsd.integer), ast.filter.GreaterThan(0)))

    def test_distance(self):
        # type must be a literal
        self.assertRaises(errors.ConsistencyError, self.validate._distance, self.schema.node(ns.bsfs.Node),
            ast.filter.Distance([1,2,3], 1, False))
        # type must be a feature
        self.assertRaises(errors.ConsistencyError, self.validate._distance, self.schema.literal(ns.bsfs.Array),
            ast.filter.Distance([1,2,3], 1, False))
        # type must be in the schema
        self.assertRaises(errors.ConsistencyError, self.validate._distance, self.schema.literal(ns.bsfs.Feature).child(ns.bsfs.Invalid),
            ast.filter.Distance([1,2,3], 1, False))
        # FIXME: reference must be a numpy array
        # reference must have the correct dimension
        self.assertRaises(errors.ConsistencyError, self.validate._distance, self.schema.literal(ns.bsfs.Colors),
            ast.filter.Distance([1,2,3], 1, False))
        # FIXME: reference must have the correct dtype
        # distance accepts correct expressions
        self.assertIsNone(self.validate._distance(self.schema.literal(ns.bsfs.Colors), ast.filter.Distance([1,2,3,4,5], 1, False)))


class TestFetch(unittest.TestCase):
    def setUp(self):
        self.schema = _schema.from_string('''
            prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
            prefix xsd: <http://www.w3.org/2001/XMLSchema#>

            prefix bsfs: <http://bsfs.ai/schema/>
            prefix bse: <http://bsfs.ai/schema/Entity#>

            bsfs:Entity rdfs:subClassOf bsfs:Node .
            bsfs:Tag rdfs:subClassOf bsfs:Node .
            xsd:string rdfs:subClassOf bsfs:Literal .

            bse:filename rdfs:subClassOf bsfs:Predicate ;
                rdfs:domain bsfs:Node ;
                rdfs:range xsd:string .

            bse:tag rdfs:subClassOf bsfs:Predicate ;
                rdfs:domain bsfs:Entity ;
                rdfs:range bsfs:Tag .

            bse:label rdfs:subClassOf bsfs:Predicate ;
                rdfs:domain bsfs:Tag ;
                rdfs:range xsd:string .

            ''')
        self.validate = Fetch(self.schema)

    def test_call(self):
        # call accepts correct expressions
        self.assertTrue(self.validate(self.schema.node(ns.bsfs.Entity),
            ast.fetch.Fetch(ns.bse.tag, ast.fetch.Value(ns.bse.label, 'value'))))
        self.assertTrue(self.validate(self.schema.node(ns.bsfs.Entity),
            ast.fetch.Fetch(ns.bse.tag, ast.fetch.This('this'))))
        self.assertTrue(self.validate(self.schema.node(ns.bsfs.Entity),
            ast.fetch.This('this')))
        self.assertTrue(self.validate(self.schema.node(ns.bsfs.Entity),
            ast.fetch.All(ast.fetch.This('this'), ast.fetch.Node(ns.bse.tag, 'node'), ast.fetch.Value(ns.bse.filename, 'value'))))
        # type must be a Node
        self.assertRaises(TypeError, self.validate, 1234, ast.fetch.This('this'))
        self.assertRaises(TypeError, self.validate, 'foobar', ast.fetch.This('this'))
        self.assertRaises(TypeError, self.validate, self.schema.literal(ns.bsfs.Literal), ast.fetch.This('this'))
        # type must be in the schema
        self.assertRaises(errors.ConsistencyError, self.validate, self.schema.node(ns.bsfs.Node).child(ns.bsfs.Invalid),
            ast.fetch.FetchExpression())
        # expression must be a fetch expression
        self.assertRaises(TypeError, self.validate, self.schema.node(ns.bsfs.Entity), 1234)
        self.assertRaises(TypeError, self.validate, self.schema.node(ns.bsfs.Entity), 'hello')
        self.assertRaises(TypeError, self.validate, self.schema.node(ns.bsfs.Entity), ast.filter.FilterExpression())
        # expression must be valid
        self.assertRaises(errors.ConsistencyError, self.validate, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Fetch(ns.bse.tag, ast.fetch.Node(ns.bse.label, 'node')))
        self.assertRaises(errors.ConsistencyError, self.validate, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Value(ns.bse.tag, 'value'))

    def test_routing(self):
        # Node passes _branch, _named, and _node checks
        self.assertRaises(errors.ConsistencyError, self.validate._parse_fetch_expression, self.schema.node(ns.bsfs.Node),
            ast.fetch.Node(ns.bse.tag, 'node')) # fails in _branch
        self.assertRaises(errors.BackendError, self.validate._parse_fetch_expression, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Node(ns.bse.tag, '')) # fails in _named
        self.assertRaises(errors.ConsistencyError, self.validate._parse_fetch_expression, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Node(ns.bse.label, 'node')) # fails in _node
        # Value passes _branch, _named, and _value checks
        self.assertRaises(errors.ConsistencyError, self.validate._parse_fetch_expression, self.schema.node(ns.bsfs.Node),
            ast.fetch.Value(ns.bse.label, 'value')) # fails in _branch
        self.assertRaises(errors.BackendError, self.validate._parse_fetch_expression, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Value(ns.bse.filename, '')) # fails in _named
        self.assertRaises(errors.ConsistencyError, self.validate._parse_fetch_expression, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Value(ns.bse.tag, 'value')) # fails in _value
        # Fetch passes _branch and _fetch checks
        self.assertRaises(errors.ConsistencyError, self.validate._parse_fetch_expression, self.schema.node(ns.bsfs.Node),
            ast.fetch.Fetch(ns.bse.tag, ast.fetch.This('this'))) # fails in _branch
        self.assertRaises(errors.ConsistencyError, self.validate._parse_fetch_expression, self.schema.node(ns.bsfs.Node),
            ast.fetch.Fetch(ns.bse.filename, ast.fetch.This('this'))) # fails in _fetch
        # invalid expressions cannot be parsed
        type_ = self.schema.node(ns.bsfs.Node)
        self.assertRaises(errors.BackendError, self.validate._parse_fetch_expression, type_,
            ast.filter.FilterExpression())
        self.assertRaises(errors.BackendError, self.validate._parse_fetch_expression, type_,
            1234)
        self.assertRaises(errors.BackendError, self.validate._parse_fetch_expression, type_,
            'hello world')

    def test_all(self):
        # all accepts correct expressions
        self.assertIsNone(self.validate._all(self.schema.node(ns.bsfs.Entity),
            ast.fetch.All(ast.fetch.Value(ns.bse.filename, 'value'), ast.fetch.Node(ns.bse.tag, 'node'))))
        # child expressions must be valid
        self.assertRaises(errors.ConsistencyError, self.validate._all, self.schema.node(ns.bsfs.Entity),
            ast.fetch.All(ast.fetch.Value(ns.bse.tag, 'value')))
        self.assertRaises(errors.ConsistencyError, self.validate._all, self.schema.node(ns.bsfs.Entity),
            ast.fetch.All(ast.fetch.Value(ns.bse.filename, 'value'), ast.fetch.Node(ns.bse.filename, 'node')))
        self.assertRaises(errors.ConsistencyError, self.validate._all, self.schema.node(ns.bsfs.Entity),
            ast.fetch.All(ast.fetch.Value(ns.bse.tag, 'value'), ast.fetch.Node(ns.bse.tag, 'node')))
        self.assertRaises(errors.ConsistencyError, self.validate._all, self.schema.node(ns.bsfs.Entity),
            ast.fetch.All(ast.fetch.Value(ns.bse.tag, 'value'), ast.fetch.Node(ns.bse.filename, 'node')))

    def test_branch(self):
        # branch accepts correct expressions
        self.assertIsNone(self.validate._branch(self.schema.node(ns.bsfs.Entity),
            ast.fetch._Branch(ns.bse.filename)))
        self.assertIsNone(self.validate._branch(self.schema.node(ns.bsfs.Entity),
            ast.fetch.Fetch(ns.bse.tag, ast.fetch.This('this'))))
        self.assertIsNone(self.validate._branch(self.schema.node(ns.bsfs.Entity),
            ast.fetch.Value(ns.bse.filename, 'value')))
        self.assertIsNone(self.validate._branch(self.schema.node(ns.bsfs.Entity),
            ast.fetch.Node(ns.bse.tag, 'node')))
        # type must be a node
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.literal(ns.bsfs.Literal),
            ast.fetch._Branch(ns.bse.filename))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.literal(ns.bsfs.Literal),
            ast.fetch.Fetch(ns.bse.tag, ast.fetch.This('this')))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.literal(ns.bsfs.Literal),
            ast.fetch.Value(ns.bse.filename, 'value'))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.literal(ns.bsfs.Literal),
            ast.fetch.Node(ns.bse.tag, 'node'))
        # type must be in the schema
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Node).child(ns.bsfs.Invalid),
            ast.fetch._Branch(ns.bse.filename))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Node).child(ns.bsfs.Invalid),
            ast.fetch.Fetch(ns.bse.tag, ast.fetch.This('this')))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Node).child(ns.bsfs.Invalid),
            ast.fetch.Value(ns.bse.filename, 'value'))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Node).child(ns.bsfs.Invalid),
            ast.fetch.Node(ns.bse.tag, 'node'))
        # predicate must be in the schema
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Entity),
            ast.fetch._Branch(ns.bse.invalid))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Fetch(ns.bse.invalid, ast.fetch.This('this')))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Value(ns.bse.invalid, 'value'))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Node(ns.bse.invalid, 'node'))
        # predicate's domain must be related to the type
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Entity),
            ast.fetch._Branch(ns.bse.label))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Fetch(ns.bse.label, ast.fetch.This('this')))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Node(ns.bse.label, 'node'))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Value(ns.bse.label, 'value'))
        # predicate's domain cannot be a supertype
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Node),
            ast.fetch._Branch(ns.bse.tag))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Node),
            ast.fetch.Fetch(ns.bse.tag, ast.fetch.This('this')))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Node),
            ast.fetch.Node(ns.bse.tag, 'node'))
        self.assertRaises(errors.ConsistencyError, self.validate._branch, self.schema.node(ns.bsfs.Node),
            ast.fetch.Value(ns.bse.tag, 'value'))
        # predicate's domain can be a subtype
        self.assertIsNone(self.validate._branch(self.schema.node(ns.bsfs.Entity),
            ast.fetch._Branch(ns.bse.filename)))
        self.assertIsNone(self.validate._branch(self.schema.node(ns.bsfs.Entity),
            ast.fetch.Value(ns.bse.filename, 'value')))

    def test_fetch(self):
        # fetch accepts correct expressions
        self.assertIsNone(self.validate._fetch(self.schema.node(ns.bsfs.Node),
            ast.fetch.Fetch(ns.bse.tag, ast.fetch.Value(ns.bse.label, 'value'))))
        # range must be a node
        self.assertRaises(errors.ConsistencyError, self.validate._fetch, self.schema.node(ns.bsfs.Node),
            ast.fetch.Fetch(ns.bse.filename, ast.fetch.This('this')))
        # child expression must be valid
        self.assertRaises(errors.ConsistencyError, self.validate._fetch, self.schema.node(ns.bsfs.Node),
            ast.fetch.Fetch(ns.bse.tag, ast.fetch.Node(ns.bse.label, 'node')))

    def test_named(self):
        # named accepts correct expressions
        self.assertIsNone(self.validate._named(self.schema.node(ns.bsfs.Entity),
            ast.fetch.Node(ns.bse.tag, 'node')))
        self.assertIsNone(self.validate._named(self.schema.node(ns.bsfs.Entity),
            ast.fetch.Value(ns.bse.filename, 'value')))
        # name must be non-empty
        self.assertRaises(errors.BackendError, self.validate._named, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Node(ns.bse.tag, ''))
        self.assertRaises(errors.BackendError, self.validate._named, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Value(ns.bse.filename, ''))

    def test_node(self):
        # node accepts correct expressions
        self.assertIsNone(self.validate._node(self.schema.node(ns.bsfs.Entity),
            ast.fetch.Node(ns.bse.tag, 'node')))
        # range must be a node
        self.assertRaises(errors.ConsistencyError, self.validate._node, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Node(ns.bse.filename, 'node'))

    def test_value(self):
        # value accepts correct expressions
        self.assertIsNone(self.validate._value(self.schema.node(ns.bsfs.Entity),
            ast.fetch.Value(ns.bse.filename, 'value')))
        # range must be a literal
        self.assertRaises(errors.ConsistencyError, self.validate._value, self.schema.node(ns.bsfs.Entity),
            ast.fetch.Value(ns.bse.tag, 'value'))

    def test_this(self):
        # this accepts correct expressions
        self.assertIsNone(self.validate._this(self.schema.node(ns.bsfs.Entity), ast.fetch.This('this')))
        # type must be a node
        self.assertRaises(errors.ConsistencyError, self.validate._this, self.schema.literal(ns.bsfs.Literal),
            ast.fetch.This('this'))
        self.assertRaises(errors.ConsistencyError, self.validate._this, self.schema.predicate(ns.bsfs.Predicate),
            ast.fetch.This('this'))
        # type must be in the schema
        self.assertRaises(errors.ConsistencyError, self.validate._this, self.schema.node(ns.bsfs.Node).child(ns.bsfs.Invalid),
            ast.fetch.This('this'))
        # name must be non-empty
        self.assertRaises(errors.BackendError, self.validate._this, self.schema.node(ns.bsfs.Entity), ast.fetch.This(''))


## main ##

if __name__ == '__main__':
    unittest.main()

## EOF ##