diff -r 058bb3dc685f -r 0b59724cb3f2 cubicweb/test/unittest_rqlrewrite.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cubicweb/test/unittest_rqlrewrite.py	Sat Jan 16 13:48:51 2016 +0100
@@ -0,0 +1,816 @@
+# copyright 2003-2014 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
+#
+# This file is part of CubicWeb.
+#
+# CubicWeb is free software: you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free
+# Software Foundation, either version 2.1 of the License, or (at your option)
+# any later version.
+#
+# CubicWeb is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+# FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
+
+from six import string_types
+
+from logilab.common.testlib import unittest_main, TestCase
+from logilab.common.testlib import mock_object
+from yams import BadSchemaDefinition
+from yams.buildobjs import RelationDefinition
+from rql import parse, nodes, RQLHelper
+
+from cubicweb import Unauthorized, rqlrewrite
+from cubicweb.schema import RRQLExpression, ERQLExpression
+from cubicweb.devtools import repotest, TestServerConfiguration, BaseApptestConfiguration
+
+
+def setUpModule(*args):
+    global rqlhelper, schema
+    config = TestServerConfiguration(RQLRewriteTC.datapath('rewrite'))
+    config.bootstrap_cubes()
+    schema = config.load_schema()
+    schema.add_relation_def(RelationDefinition(subject='Card', name='in_state',
+                                               object='State', cardinality='1*'))
+    rqlhelper = RQLHelper(schema, special_relations={'eid': 'uid',
+                                                     'has_text': 'fti'})
+    repotest.do_monkey_patch()
+
+def tearDownModule(*args):
+    repotest.undo_monkey_patch()
+    global rqlhelper, schema
+    del rqlhelper, schema
+
+def eid_func_map(eid):
+    return {1: 'CWUser',
+            2: 'Card',
+            3: 'Affaire'}[eid]
+
+def _prepare_rewriter(rewriter_cls, kwargs):
+    class FakeVReg:
+        schema = schema
+        @staticmethod
+        def solutions(sqlcursor, rqlst, kwargs):
+            rqlhelper.compute_solutions(rqlst, {'eid': eid_func_map}, kwargs=kwargs)
+        class rqlhelper:
+            @staticmethod
+            def annotate(rqlst):
+                rqlhelper.annotate(rqlst)
+            @staticmethod
+            def simplify(mainrqlst, needcopy=False):
+                rqlhelper.simplify(rqlst, needcopy)
+    return rewriter_cls(mock_object(vreg=FakeVReg, user=(mock_object(eid=1))))
+
+def rewrite(rqlst, snippets_map, kwargs, existingvars=None):
+    rewriter = _prepare_rewriter(rqlrewrite.RQLRewriter, kwargs)
+    snippets = []
+    for v, exprs in sorted(snippets_map.items()):
+        rqlexprs = [isinstance(snippet, string_types)
+                    and mock_object(snippet_rqlst=parse(u'Any X WHERE '+snippet).children[0],
+                                    expression=u'Any X WHERE '+snippet)
+                    or snippet
+                    for snippet in exprs]
+        snippets.append((dict([v]), rqlexprs))
+    rqlhelper.compute_solutions(rqlst.children[0], {'eid': eid_func_map}, kwargs=kwargs)
+    rewriter.rewrite(rqlst.children[0], snippets, kwargs, existingvars)
+    test_vrefs(rqlst.children[0])
+    return rewriter.rewritten
+
+def test_vrefs(node):
+    vrefmaps = {}
+    selects = []
+    for vref in node.iget_nodes(nodes.VariableRef):
+        stmt = vref.stmt
+        try:
+            vrefmaps[stmt].setdefault(vref.name, set()).add(vref)
+        except KeyError:
+            vrefmaps[stmt] = {vref.name: set( (vref,) )}
+            selects.append(stmt)
+    assert node in selects, (node, selects)
+    for stmt in selects:
+        for var in stmt.defined_vars.values():
+            assert var.stinfo['references']
+            vrefmap = vrefmaps[stmt]
+            assert not (var.stinfo['references'] ^ vrefmap[var.name]), (node.as_string(), var, var.stinfo['references'], vrefmap[var.name])
+
+
+class RQLRewriteTC(TestCase):
+    """a faire:
+
+    * optimisation: detecter les relations utilisees dans les rqlexpressions qui
+      sont presentes dans la requete de depart pour les reutiliser si possible
+
+    * "has_<ACTION>_permission" ?
+    """
+
+    def test_base_var(self):
+        constraint = ('X in_state S, U in_group G, P require_state S,'
+                           'P name "read", P require_group G')
+        rqlst = parse(u'Card C')
+        rewrite(rqlst, {('C', 'X'): (constraint,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         u'Any C WHERE C is Card, B eid %(D)s, '
+                          'EXISTS(C in_state A, B in_group E, F require_state A, '
+                          'F name "read", F require_group E, A is State, E is CWGroup, F is CWPermission)')
+
+    def test_multiple_var(self):
+        card_constraint = ('X in_state S, U in_group G, P require_state S,'
+                           'P name "read", P require_group G')
+        affaire_constraints = ('X ref LIKE "PUBLIC%"', 'U in_group G, G name "public"')
+        kwargs = {'u':2}
+        rqlst = parse(u'Any S WHERE S documented_by C, C eid %(u)s')
+        rewrite(rqlst, {('C', 'X'): (card_constraint,), ('S', 'X'): affaire_constraints},
+                kwargs)
+        self.assertMultiLineEqual(
+            rqlst.as_string(),
+            u'Any S WHERE S documented_by C, C eid %(u)s, B eid %(D)s, '
+             'EXISTS(C in_state A, B in_group E, F require_state A, '
+             'F name "read", F require_group E, A is State, E is CWGroup, F is CWPermission), '
+             '(EXISTS(S ref LIKE "PUBLIC%")) OR (EXISTS(B in_group G, G name "public", G is CWGroup)), '
+             'S is Affaire')
+        self.assertIn('D', kwargs)
+
+    def test_or(self):
+        constraint = '(X identity U) OR (X in_state ST, CL identity U, CL in_state ST, ST name "subscribed")'
+        rqlst = parse(u'Any S WHERE S owned_by C, C eid %(u)s, S is in (CWUser, CWGroup)')
+        rewrite(rqlst, {('C', 'X'): (constraint,)}, {'u':1})
+        self.assertEqual(rqlst.as_string(),
+                         'Any S WHERE S owned_by C, C eid %(u)s, S is IN(CWUser, CWGroup), A eid %(B)s, '
+                         'EXISTS((C identity A) OR (C in_state D, E identity A, '
+                         'E in_state D, D name "subscribed"), D is State, E is CWUser)')
+
+    def test_simplified_rqlst(self):
+        constraint = ('X in_state S, U in_group G, P require_state S,'
+                           'P name "read", P require_group G')
+        rqlst = parse(u'Any 2') # this is the simplified rql st for Any X WHERE X eid 12
+        rewrite(rqlst, {('2', 'X'): (constraint,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         u'Any 2 WHERE B eid %(C)s, '
+                          'EXISTS(2 in_state A, B in_group D, E require_state A, '
+                          'E name "read", E require_group D, A is State, D is CWGroup, E is CWPermission)')
+
+    def test_optional_var_1(self):
+        constraint = ('X in_state S, U in_group G, P require_state S,'
+                           'P name "read", P require_group G')
+        rqlst = parse(u'Any A,C WHERE A documented_by C?')
+        rewrite(rqlst, {('C', 'X'): (constraint,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         u'Any A,C WHERE A documented_by C?, A is Affaire '
+                          'WITH C BEING '
+                          '(Any C WHERE EXISTS(C in_state B, D in_group F, G require_state B, G name "read", '
+                          'G require_group F), D eid %(A)s, C is Card)')
+
+    def test_optional_var_2(self):
+        constraint = ('X in_state S, U in_group G, P require_state S,'
+                           'P name "read", P require_group G')
+        rqlst = parse(u'Any A,C,T WHERE A documented_by C?, C title T')
+        rewrite(rqlst, {('C', 'X'): (constraint,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         u'Any A,C,T WHERE A documented_by C?, A is Affaire '
+                          'WITH C,T BEING '
+                          '(Any C,T WHERE C title T, EXISTS(C in_state B, D in_group F, '
+                          'G require_state B, G name "read", G require_group F), '
+                          'D eid %(A)s, C is Card)')
+
+    def test_optional_var_3(self):
+        constraint1 = ('X in_state S, U in_group G, P require_state S,'
+                       'P name "read", P require_group G')
+        constraint2 = 'X in_state S, S name "public"'
+        rqlst = parse(u'Any A,C,T WHERE A documented_by C?, C title T')
+        rewrite(rqlst, {('C', 'X'): (constraint1, constraint2)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         u'Any A,C,T WHERE A documented_by C?, A is Affaire '
+                          'WITH C,T BEING (Any C,T WHERE C title T, '
+                          '(EXISTS(C in_state B, D in_group F, G require_state B, G name "read", G require_group F)) '
+                          'OR (EXISTS(C in_state E, E name "public")), '
+                          'D eid %(A)s, C is Card)')
+
+    def test_optional_var_4(self):
+        constraint1 = 'A created_by U, X documented_by A'
+        constraint2 = 'A created_by U, X concerne A'
+        constraint3 = 'X created_by U'
+        rqlst = parse(u'Any X,LA,Y WHERE LA? documented_by X, LA concerne Y')
+        rewrite(rqlst, {('LA', 'X'): (constraint1, constraint2),
+                        ('X', 'X'): (constraint3,),
+                        ('Y', 'X'): (constraint3,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                             u'Any X,LA,Y WHERE LA? documented_by X, LA concerne Y, B eid %(C)s, '
+                             'EXISTS(X created_by B), EXISTS(Y created_by B), '
+                             'X is Card, Y is IN(Division, Note, Societe) '
+                             'WITH LA BEING (Any LA WHERE (EXISTS(A created_by B, LA documented_by A)) OR (EXISTS(E created_by B, LA concerne E)), '
+                             'B eid %(D)s, LA is Affaire)')
+
+
+    def test_ambiguous_optional_same_exprs(self):
+        """See #3013535"""
+        # see test of the same name in RewriteFullTC: original problem is
+        # unreproducible here because it actually lies in
+        # RQLRewriter.insert_local_checks
+        rqlst = parse(u'Any A,AR,X,CD WHERE A concerne X?, A ref AR, A eid %(a)s, X creation_date CD')
+        rewrite(rqlst, {('X', 'X'): ('X created_by U',),}, {'a': 3})
+        self.assertEqual(rqlst.as_string(),
+                         u'Any A,AR,X,CD WHERE A concerne X?, A ref AR, A eid %(a)s WITH X,CD BEING (Any X,CD WHERE X creation_date CD, EXISTS(X created_by B), B eid %(A)s, X is IN(Division, Note, Societe))')
+
+    def test_optional_var_inlined(self):
+        c1 = ('X require_permission P')
+        c2 = ('X inlined_card O, O require_permission P')
+        rqlst = parse(u'Any C,A,R WHERE A? inlined_card C, A ref R')
+        rewrite(rqlst, {('C', 'X'): (c1,),
+                        ('A', 'X'): (c2,),
+                        }, {})
+        # XXX suboptimal
+        self.assertEqual(rqlst.as_string(),
+                         "Any C,A,R WITH A,C,R BEING "
+                         "(Any A,C,R WHERE A? inlined_card C, A ref R, "
+                         "(A is NULL) OR (EXISTS(A inlined_card B, B require_permission D, "
+                         "B is Card, D is CWPermission)), "
+                         "A is Affaire, C is Card, EXISTS(C require_permission E, E is CWPermission))")
+
+    # def test_optional_var_inlined_has_perm(self):
+    #     c1 = ('X require_permission P')
+    #     c2 = ('X inlined_card O, U has_read_permission O')
+    #     rqlst = parse(u'Any C,A,R WHERE A? inlined_card C, A ref R')
+    #     rewrite(rqlst, {('C', 'X'): (c1,),
+    #                     ('A', 'X'): (c2,),
+    #                     }, {})
+    #     self.assertEqual(rqlst.as_string(),
+    #                          "")
+
+    def test_optional_var_inlined_imbricated_error(self):
+        c1 = ('X require_permission P')
+        c2 = ('X inlined_card O, O require_permission P')
+        rqlst = parse(u'Any C,A,R,A2,R2 WHERE A? inlined_card C, A ref R,A2? inlined_card C, A2 ref R2')
+        self.assertRaises(BadSchemaDefinition,
+                          rewrite, rqlst, {('C', 'X'): (c1,),
+                                           ('A', 'X'): (c2,),
+                                           ('A2', 'X'): (c2,),
+                                           }, {})
+
+    def test_optional_var_inlined_linked(self):
+        c1 = ('X require_permission P')
+        c2 = ('X inlined_card O, O require_permission P')
+        rqlst = parse(u'Any A,W WHERE A inlined_card C?, C inlined_note N, '
+                      'N inlined_affaire W')
+        rewrite(rqlst, {('C', 'X'): (c1,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         'Any A,W WHERE A inlined_card C?, A is Affaire '
+                         'WITH C,N,W BEING (Any C,N,W WHERE C inlined_note N, '
+                         'N inlined_affaire W, EXISTS(C require_permission B), '
+                         'C is Card, N is Note, W is Affaire)')
+
+    def test_relation_optimization_1_lhs(self):
+        # since Card in_state State as monovalued cardinality, the in_state
+        # relation used in the rql expression can be ignored and S replaced by
+        # the variable from the incoming query
+        snippet = ('X in_state S, S name "hop"')
+        rqlst = parse(u'Card C WHERE C in_state STATE')
+        rewrite(rqlst, {('C', 'X'): (snippet,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         'Any C WHERE C in_state STATE, C is Card, '
+                         'EXISTS(STATE name "hop"), STATE is State')
+
+    def test_relation_optimization_1_rhs(self):
+        snippet = ('TW subworkflow_exit X, TW name "hop"')
+        rqlst = parse(u'WorkflowTransition C WHERE C subworkflow_exit EXIT')
+        rewrite(rqlst, {('EXIT', 'X'): (snippet,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         'Any C WHERE C subworkflow_exit EXIT, C is WorkflowTransition, '
+                         'EXISTS(C name "hop"), EXIT is SubWorkflowExitPoint')
+
+    def test_relation_optimization_2_lhs(self):
+        # optional relation can be shared if also optional in the snippet
+        snippet = ('X in_state S?, S name "hop"')
+        rqlst = parse(u'Card C WHERE C in_state STATE?')
+        rewrite(rqlst, {('C', 'X'): (snippet,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         'Any C WHERE C in_state STATE?, C is Card, '
+                         'EXISTS(STATE name "hop"), STATE is State')
+    def test_relation_optimization_2_rhs(self):
+        snippet = ('TW? subworkflow_exit X, TW name "hop"')
+        rqlst = parse(u'SubWorkflowExitPoint EXIT WHERE C? subworkflow_exit EXIT')
+        rewrite(rqlst, {('EXIT', 'X'): (snippet,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         'Any EXIT WHERE C? subworkflow_exit EXIT, EXIT is SubWorkflowExitPoint, '
+                         'EXISTS(C name "hop"), C is WorkflowTransition')
+
+    def test_relation_optimization_3_lhs(self):
+        # optional relation in the snippet but not in the orig tree can be shared
+        snippet = ('X in_state S?, S name "hop"')
+        rqlst = parse(u'Card C WHERE C in_state STATE')
+        rewrite(rqlst, {('C', 'X'): (snippet,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         'Any C WHERE C in_state STATE, C is Card, '
+                         'EXISTS(STATE name "hop"), STATE is State')
+
+    def test_relation_optimization_3_rhs(self):
+        snippet = ('TW? subworkflow_exit X, TW name "hop"')
+        rqlst = parse(u'WorkflowTransition C WHERE C subworkflow_exit EXIT')
+        rewrite(rqlst, {('EXIT', 'X'): (snippet,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         'Any C WHERE C subworkflow_exit EXIT, C is WorkflowTransition, '
+                         'EXISTS(C name "hop"), EXIT is SubWorkflowExitPoint')
+
+    def test_relation_non_optimization_1_lhs(self):
+        # but optional relation in the orig tree but not in the snippet can't be shared
+        snippet = ('X in_state S, S name "hop"')
+        rqlst = parse(u'Card C WHERE C in_state STATE?')
+        rewrite(rqlst, {('C', 'X'): (snippet,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         'Any C WHERE C in_state STATE?, C is Card, '
+                         'EXISTS(C in_state A, A name "hop", A is State), STATE is State')
+
+    def test_relation_non_optimization_1_rhs(self):
+        snippet = ('TW subworkflow_exit X, TW name "hop"')
+        rqlst = parse(u'SubWorkflowExitPoint EXIT WHERE C? subworkflow_exit EXIT')
+        rewrite(rqlst, {('EXIT', 'X'): (snippet,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         'Any EXIT WHERE C? subworkflow_exit EXIT, EXIT is SubWorkflowExitPoint, '
+                         'EXISTS(A subworkflow_exit EXIT, A name "hop", A is WorkflowTransition), '
+                         'C is WorkflowTransition')
+
+    def test_relation_non_optimization_2(self):
+        """See #3024730"""
+        # 'X inlined_note N' must not be shared with 'C inlined_note N'
+        # previously inserted, else this may introduce duplicated results, as N
+        # will then be shared by multiple EXISTS and so at SQL generation time,
+        # the table will be in the FROM clause of the outermost query
+        rqlst = parse(u'Any A,C WHERE A inlined_card C')
+        rewrite(rqlst, {('A', 'X'): ('X inlined_card C, C inlined_note N, N owned_by U',),
+                        ('C', 'X'): ('X inlined_note N, N owned_by U',)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         'Any A,C WHERE A inlined_card C, D eid %(E)s, '
+                         'EXISTS(C inlined_note B, B owned_by D, B is Note), '
+                         'EXISTS(C inlined_note F, F owned_by D, F is Note), '
+                         'A is Affaire, C is Card')
+
+    def test_unsupported_constraint_1(self):
+        # CWUser doesn't have require_permission
+        trinfo_constraint = ('X wf_info_for Y, Y require_permission P, P name "read"')
+        rqlst = parse(u'Any U,T WHERE U is CWUser, T wf_info_for U')
+        self.assertRaises(Unauthorized, rewrite, rqlst, {('T', 'X'): (trinfo_constraint,)}, {})
+
+    def test_unsupported_constraint_2(self):
+        trinfo_constraint = ('X wf_info_for Y, Y require_permission P, P name "read"')
+        rqlst = parse(u'Any U,T WHERE U is CWUser, T wf_info_for U')
+        rewrite(rqlst, {('T', 'X'): (trinfo_constraint, 'X wf_info_for Y, Y in_group G, G name "managers"')}, {})
+        self.assertEqual(rqlst.as_string(),
+                         u'Any U,T WHERE U is CWUser, T wf_info_for U, '
+                          'EXISTS(U in_group B, B name "managers", B is CWGroup), T is TrInfo')
+
+    def test_unsupported_constraint_3(self):
+        self.skipTest('raise unauthorized for now')
+        trinfo_constraint = ('X wf_info_for Y, Y require_permission P, P name "read"')
+        rqlst = parse(u'Any T WHERE T wf_info_for X')
+        rewrite(rqlst, {('T', 'X'): (trinfo_constraint, 'X in_group G, G name "managers"')}, {})
+        self.assertEqual(rqlst.as_string(),
+                         u'XXX dunno what should be generated')
+
+    def test_add_ambiguity_exists(self):
+        constraint = ('X concerne Y')
+        rqlst = parse(u'Affaire X')
+        rewrite(rqlst, {('X', 'X'): (constraint,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         u"Any X WHERE X is Affaire, ((EXISTS(X concerne A, A is Division)) OR (EXISTS(X concerne C, C is Societe))) OR (EXISTS(X concerne B, B is Note))")
+
+    def test_add_ambiguity_outerjoin(self):
+        constraint = ('X concerne Y')
+        rqlst = parse(u'Any X,C WHERE X? documented_by C')
+        rewrite(rqlst, {('X', 'X'): (constraint,)}, {})
+        # ambiguity are kept in the sub-query, no need to be resolved using OR
+        self.assertEqual(rqlst.as_string(),
+                         u"Any X,C WHERE X? documented_by C, C is Card WITH X BEING (Any X WHERE EXISTS(X concerne A), X is Affaire)")
+
+
+    def test_rrqlexpr_nonexistant_subject_1(self):
+        constraint = RRQLExpression('S owned_by U')
+        rqlst = parse(u'Card C')
+        rewrite(rqlst, {('C', 'S'): (constraint,)}, {}, 'SU')
+        self.assertEqual(rqlst.as_string(),
+                         u"Any C WHERE C is Card, A eid %(B)s, EXISTS(C owned_by A)")
+        rqlst = parse(u'Card C')
+        rewrite(rqlst, {('C', 'S'): (constraint,)}, {}, 'OU')
+        self.assertEqual(rqlst.as_string(),
+                         u"Any C WHERE C is Card")
+        rqlst = parse(u'Card C')
+        rewrite(rqlst, {('C', 'S'): (constraint,)}, {}, 'SOU')
+        self.assertEqual(rqlst.as_string(),
+                         u"Any C WHERE C is Card, A eid %(B)s, EXISTS(C owned_by A)")
+
+    def test_rrqlexpr_nonexistant_subject_2(self):
+        constraint = RRQLExpression('S owned_by U, O owned_by U, O is Card')
+        rqlst = parse(u'Card C')
+        rewrite(rqlst, {('C', 'S'): (constraint,)}, {}, 'SU')
+        self.assertEqual(rqlst.as_string(),
+                         'Any C WHERE C is Card, A eid %(B)s, EXISTS(C owned_by A)')
+        rqlst = parse(u'Card C')
+        rewrite(rqlst, {('C', 'S'): (constraint,)}, {}, 'OU')
+        self.assertEqual(rqlst.as_string(),
+                         'Any C WHERE C is Card, B eid %(D)s, EXISTS(A owned_by B, A is Card)')
+        rqlst = parse(u'Card C')
+        rewrite(rqlst, {('C', 'S'): (constraint,)}, {}, 'SOU')
+        self.assertEqual(rqlst.as_string(),
+                         'Any C WHERE C is Card, A eid %(B)s, EXISTS(C owned_by A, D owned_by A, D is Card)')
+
+    def test_rrqlexpr_nonexistant_subject_3(self):
+        constraint = RRQLExpression('U in_group G, G name "users"')
+        rqlst = parse(u'Card C')
+        rewrite(rqlst, {('C', 'S'): (constraint,)}, {}, 'SU')
+        self.assertEqual(rqlst.as_string(),
+                         u'Any C WHERE C is Card, A eid %(B)s, EXISTS(A in_group D, D name "users", D is CWGroup)')
+
+    def test_rrqlexpr_nonexistant_subject_4(self):
+        constraint = RRQLExpression('U in_group G, G name "users", S owned_by U')
+        rqlst = parse(u'Card C')
+        rewrite(rqlst, {('C', 'S'): (constraint,)}, {}, 'SU')
+        self.assertEqual(rqlst.as_string(),
+                         u'Any C WHERE C is Card, A eid %(B)s, EXISTS(A in_group D, D name "users", C owned_by A, D is CWGroup)')
+        rqlst = parse(u'Card C')
+        rewrite(rqlst, {('C', 'S'): (constraint,)}, {}, 'OU')
+        self.assertEqual(rqlst.as_string(),
+                         u'Any C WHERE C is Card, A eid %(B)s, EXISTS(A in_group D, D name "users", D is CWGroup)')
+
+    def test_rrqlexpr_nonexistant_subject_5(self):
+        constraint = RRQLExpression('S owned_by Z, O owned_by Z, O is Card')
+        rqlst = parse(u'Card C')
+        rewrite(rqlst, {('C', 'S'): (constraint,)}, {}, 'S')
+        self.assertEqual(rqlst.as_string(),
+                         u"Any C WHERE C is Card, EXISTS(C owned_by A, A is CWUser)")
+
+    def test_rqlexpr_not_relation_1_1(self):
+        constraint = ERQLExpression('X owned_by Z, Z login "hop"', 'X')
+        rqlst = parse(u'Affaire A WHERE NOT EXISTS(A documented_by C)')
+        rewrite(rqlst, {('C', 'X'): (constraint,)}, {}, 'X')
+        self.assertEqual(rqlst.as_string(),
+                         u'Any A WHERE NOT EXISTS(A documented_by C, EXISTS(C owned_by B, B login "hop", B is CWUser), C is Card), A is Affaire')
+
+    def test_rqlexpr_not_relation_1_2(self):
+        constraint = ERQLExpression('X owned_by Z, Z login "hop"', 'X')
+        rqlst = parse(u'Affaire A WHERE NOT EXISTS(A documented_by C)')
+        rewrite(rqlst, {('A', 'X'): (constraint,)}, {}, 'X')
+        self.assertEqual(rqlst.as_string(),
+                         u'Any A WHERE NOT EXISTS(A documented_by C, C is Card), A is Affaire, EXISTS(A owned_by B, B login "hop", B is CWUser)')
+
+    def test_rqlexpr_not_relation_2(self):
+        constraint = ERQLExpression('X owned_by Z, Z login "hop"', 'X')
+        rqlst = rqlhelper.parse(u'Affaire A WHERE NOT A documented_by C', annotate=False)
+        rewrite(rqlst, {('C', 'X'): (constraint,)}, {}, 'X')
+        self.assertEqual(rqlst.as_string(),
+                         u'Any A WHERE NOT EXISTS(A documented_by C, EXISTS(C owned_by B, B login "hop", B is CWUser), C is Card), A is Affaire')
+
+    def test_rqlexpr_multiexpr_outerjoin(self):
+        c1 = ERQLExpression('X owned_by Z, Z login "hop"', 'X')
+        c2 = ERQLExpression('X owned_by Z, Z login "hip"', 'X')
+        c3 = ERQLExpression('X owned_by Z, Z login "momo"', 'X')
+        rqlst = rqlhelper.parse(u'Any A WHERE A documented_by C?', annotate=False)
+        rewrite(rqlst, {('C', 'X'): (c1, c2, c3)}, {}, 'X')
+        self.assertEqual(rqlst.as_string(),
+                         u'Any A WHERE A documented_by C?, A is Affaire '
+                         'WITH C BEING (Any C WHERE ((EXISTS(C owned_by B, B login "hop")) '
+                         'OR (EXISTS(C owned_by D, D login "momo"))) '
+                         'OR (EXISTS(C owned_by A, A login "hip")), C is Card)')
+
+    def test_multiple_erql_one_bad(self):
+        #: reproduce bug #2236985
+        #: (rqlrewrite fails to remove rewritten entry for unsupported constraint and then crash)
+        #:
+        #: This check a very rare code path triggered by the four condition below
+
+        # 1. c_ok introduce an ambiguity
+        c_ok = ERQLExpression('X concerne R')
+        # 2. c_bad is just plain wrong and won't be kept
+        # 3. but it declare a new variable
+        # 4. this variable require a rewrite
+        c_bad = ERQLExpression('X documented_by R, A in_state R')
+
+        rqlst = parse(u'Any A, R WHERE A ref R, S is Affaire')
+        rewrite(rqlst, {('A', 'X'): (c_ok, c_bad)}, {})
+
+    def test_nonregr_is_instance_of(self):
+        user_expr = ERQLExpression('NOT X in_group AF, AF name "guests"')
+        rqlst = parse(u'Any O WHERE S use_email O, S is CWUser, O is_instance_of EmailAddress')
+        rewrite(rqlst, {('S', 'X'): (user_expr,)}, {})
+        self.assertEqual(rqlst.as_string(),
+                         'Any O WHERE S use_email O, S is CWUser, O is EmailAddress, '
+                         'EXISTS(NOT S in_group A, A name "guests", A is CWGroup)')
+
+from cubicweb.devtools.testlib import CubicWebTC
+from logilab.common.decorators import classproperty
+
+class RewriteFullTC(CubicWebTC):
+    @classproperty
+    def config(cls):
+        return BaseApptestConfiguration(apphome=cls.datapath('rewrite'))
+
+    def process(self, rql, args=None):
+        if args is None:
+            args = {}
+        querier = self.repo.querier
+        union = querier.parse(rql)
+        with self.admin_access.repo_cnx() as cnx:
+            querier.solutions(cnx, union, args)
+            querier._annotate(union)
+            plan = querier.plan_factory(union, args, cnx)
+            plan.preprocess(union)
+            return union
+
+    def test_ambiguous_optional_same_exprs(self):
+        """See #3013535"""
+        edef1 = self.schema['Societe']
+        edef2 = self.schema['Division']
+        edef3 = self.schema['Note']
+        with self.temporary_permissions((edef1, {'read': (ERQLExpression('X owned_by U'),)}),
+                                        (edef2, {'read': (ERQLExpression('X owned_by U'),)}),
+                                        (edef3, {'read': (ERQLExpression('X owned_by U'),)})):
+            union = self.process('Any A,AR,X,CD WHERE A concerne X?, A ref AR, X creation_date CD')
+            self.assertEqual('Any A,AR,X,CD WHERE A concerne X?, A ref AR, A is Affaire '
+                             'WITH X,CD BEING (Any X,CD WHERE X creation_date CD, '
+                             'EXISTS(X owned_by %(A)s), X is IN(Division, Note, Societe))',
+                             union.as_string())
+
+    def test_ambiguous_optional_diff_exprs(self):
+        """See #3013554"""
+        self.skipTest('bad request generated (may generate duplicated results)')
+        edef1 = self.schema['Societe']
+        edef2 = self.schema['Division']
+        edef3 = self.schema['Note']
+        with self.temporary_permissions((edef1, {'read': (ERQLExpression('X created_by U'),)}),
+                                        (edef2, {'read': ('users',)}),
+                                        (edef3, {'read': (ERQLExpression('X owned_by U'),)})):
+            union = self.process('Any A,AR,X,CD WHERE A concerne X?, A ref AR, X creation_date CD')
+            self.assertEqual(union.as_string(), 'not generated today')
+
+
+    def test_xxxx(self):
+        edef1 = self.schema['Societe']
+        edef2 = self.schema['Division']
+        read_expr = ERQLExpression('X responsable E, U has_read_permission E')
+        with self.temporary_permissions((edef1, {'read': (read_expr,)}),
+                                        (edef2, {'read': (read_expr,)})):
+            union = self.process('Any X,AA,AC,AD ORDERBY AD DESC '
+                                 'WHERE X responsable E, X nom AA, '
+                                 'X responsable AC?, AC modification_date AD')
+            self.assertEqual('Any X,AA,AC,AD ORDERBY AD DESC '
+                             'WHERE X responsable E, X nom AA, '
+                             'X responsable AC?, AC modification_date AD, '
+                             'AC is CWUser, E is CWUser, X is IN(Division, Societe)',
+                             union.as_string())
+
+    def test_question_mark_attribute_snippet(self):
+        # see #3661918
+        from cubicweb.rqlrewrite import RQLRewriter
+        from logilab.common.decorators import monkeypatch
+        repotest.undo_monkey_patch()
+        orig_insert_snippets = RQLRewriter.insert_snippets
+        # patch insert_snippets and not rewrite, insert_snippets is already
+        # monkey patches (see above setupModule/repotest)
+        @monkeypatch(RQLRewriter)
+        def insert_snippets(self, snippets, varexistsmap=None):
+            # crash occurs if snippets are processed in a specific order, force
+            # destiny
+            if snippets[0][0] != {u'N': 'X'}:
+                snippets = list(reversed(snippets))
+            return orig_insert_snippets(self, snippets, varexistsmap)
+        try:
+            with self.temporary_permissions(
+                    (self.schema['Affaire'],
+                     {'read': (ERQLExpression('X ref "blah"'), )}),
+                    (self.schema['Note'],
+                     {'read': (ERQLExpression(
+                         'EXISTS(X inlined_affaire Z), EXISTS(Z owned_by U)'), )}),
+            ):
+                union = self.process(
+                    'Any A,COUNT(N) GROUPBY A '
+                    'WHERE A is Affaire, N? inlined_affaire A')
+                self.assertEqual('Any A,COUNT(N) GROUPBY A WHERE A is Affaire '
+                                 'WITH N,A BEING (Any N,A WHERE N? inlined_affaire A, '
+                                 '(N is NULL) OR (EXISTS(EXISTS(N inlined_affaire B), '
+                                 'EXISTS(B owned_by %(E)s), B is Affaire)), '
+                                 'A is Affaire, N is Note, EXISTS(A ref "blah"))',
+                                 union.as_string())
+        finally:
+            RQLRewriter.insert_snippets = orig_insert_snippets
+
+
+class RQLRelationRewriterTC(TestCase):
+    # XXX valid rules: S and O specified, not in a SET, INSERT, DELETE scope
+    #     valid uses: no outer join
+
+    # Basic tests
+    def test_base_rule(self):
+        rules = {'participated_in': 'S contributor O'}
+        rqlst = rqlhelper.parse(u'Any X WHERE X participated_in S')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any X WHERE X contributor S',
+                         rqlst.as_string())
+
+    def test_complex_rule_1(self):
+        rules = {'illustrator_of': ('C is Contribution, C contributor S, '
+                                    'C manifestation O, C role R, '
+                                    'R name "illustrator"')}
+        rqlst = rqlhelper.parse(u'Any A,B WHERE A illustrator_of B')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WHERE C is Contribution, '
+                         'C contributor A, C manifestation B, '
+                         'C role D, D name "illustrator"',
+                         rqlst.as_string())
+
+    def test_complex_rule_2(self):
+        rules = {'illustrator_of': ('C is Contribution, C contributor S, '
+                                    'C manifestation O, C role R, '
+                                    'R name "illustrator"')}
+        rqlst = rqlhelper.parse(u'Any A WHERE EXISTS(A illustrator_of B)')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A WHERE EXISTS(C is Contribution, '
+                         'C contributor A, C manifestation B, '
+                         'C role D, D name "illustrator")',
+                         rqlst.as_string())
+
+
+    def test_rewrite2(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'Any A,B WHERE A illustrator_of B, C require_permission R, S'
+                                'require_state O')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WHERE C require_permission R, S require_state O, '
+                         'D is Contribution, D contributor A, D manifestation B, D role E, '
+                         'E name "illustrator"',
+                          rqlst.as_string())
+
+    def test_rewrite3(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'Any A,B WHERE E require_permission T, A illustrator_of B')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WHERE E require_permission T, '
+                         'C is Contribution, C contributor A, C manifestation B, '
+                         'C role D, D name "illustrator"',
+                         rqlst.as_string())
+
+    def test_rewrite4(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'Any A,B WHERE C require_permission R, A illustrator_of B')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WHERE C require_permission R, '
+                         'D is Contribution, D contributor A, D manifestation B, '
+                         'D role E, E name "illustrator"',
+                         rqlst.as_string())
+
+    def test_rewrite5(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'Any A,B WHERE C require_permission R, A illustrator_of B, '
+                                'S require_state O')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WHERE C require_permission R, S require_state O, '
+                         'D is Contribution, D contributor A, D manifestation B, D role E, '
+                         'E name "illustrator"',
+                         rqlst.as_string())
+
+    # Tests for the with clause
+    def test_rewrite_with(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'Any A,B WITH A, B BEING(Any X, Y WHERE X illustrator_of Y)')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WITH A,B BEING '
+                         '(Any X,Y WHERE A is Contribution, A contributor X, '
+                         'A manifestation Y, A role B, B name "illustrator")',
+                         rqlst.as_string())
+
+    def test_rewrite_with2(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'Any A,B WHERE T require_permission C WITH A, B BEING(Any X, Y WHERE X illustrator_of Y)')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WHERE T require_permission C '
+                         'WITH A,B BEING (Any X,Y WHERE A is Contribution, '
+                         'A contributor X, A manifestation Y, A role B, B name "illustrator")',
+                         rqlst.as_string())
+
+    def test_rewrite_with3(self):
+        rules = {'participated_in': 'S contributor O'}
+        rqlst = rqlhelper.parse(u'Any A,B WHERE A participated_in B '
+                                'WITH A, B BEING(Any X,Y WHERE X contributor Y)')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WHERE A contributor B WITH A,B BEING '
+                         '(Any X,Y WHERE X contributor Y)',
+                         rqlst.as_string())
+
+    def test_rewrite_with4(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'Any A,B WHERE A illustrator_of B '
+                               'WITH A, B BEING(Any X, Y WHERE X illustrator_of Y)')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WHERE C is Contribution, '
+                         'C contributor A, C manifestation B, C role D, '
+                         'D name "illustrator" WITH A,B BEING '
+                         '(Any X,Y WHERE A is Contribution, A contributor X, '
+                         'A manifestation Y, A role B, B name "illustrator")',
+                          rqlst.as_string())
+
+    # Tests for the union
+    def test_rewrite_union(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'(Any A,B WHERE A illustrator_of B) UNION'
+                                '(Any X,Y WHERE X is CWUser, Z manifestation Y)')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('(Any A,B WHERE C is Contribution, '
+                         'C contributor A, C manifestation B, C role D, '
+                         'D name "illustrator") UNION (Any X,Y WHERE X is CWUser, Z manifestation Y)',
+                         rqlst.as_string())
+
+    def test_rewrite_union2(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'(Any Y WHERE Y match W) UNION '
+                                '(Any A WHERE A illustrator_of B) UNION '
+                                '(Any Y WHERE Y is ArtWork)')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('(Any Y WHERE Y match W) '
+                         'UNION (Any A WHERE C is Contribution, C contributor A, '
+                         'C manifestation B, C role D, D name "illustrator") '
+                         'UNION (Any Y WHERE Y is ArtWork)',
+                         rqlst.as_string())
+
+    # Tests for the exists clause
+    def test_rewrite_exists(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'(Any A,B WHERE A illustrator_of B, '
+                     'EXISTS(B is ArtWork))')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WHERE EXISTS(B is ArtWork), '
+                         'C is Contribution, C contributor A, C manifestation B, C role D, '
+                         'D name "illustrator"',
+                         rqlst.as_string())
+
+    def test_rewrite_exists2(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'(Any A,B WHERE B contributor A, EXISTS(A illustrator_of W))')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WHERE B contributor A, '
+                         'EXISTS(C is Contribution, C contributor A, C manifestation W, '
+                         'C role D, D name "illustrator")',
+                         rqlst.as_string())
+
+    def test_rewrite_exists3(self):
+        rules = {'illustrator_of': 'C is Contribution, C contributor S, '
+                'C manifestation O, C role R, R name "illustrator"'}
+        rqlst = rqlhelper.parse(u'(Any A,B WHERE A illustrator_of B, EXISTS(A illustrator_of W))')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any A,B WHERE EXISTS(C is Contribution, C contributor A, '
+                         'C manifestation W, C role D, D name "illustrator"), '
+                         'E is Contribution, E contributor A, E manifestation B, E role F, '
+                         'F name "illustrator"',
+                         rqlst.as_string())
+
+    # Test for GROUPBY
+    def test_rewrite_groupby(self):
+        rules = {'participated_in': 'S contributor O'}
+        rqlst = rqlhelper.parse(u'Any SUM(SA) GROUPBY S WHERE P participated_in S, P manifestation SA')
+        rule_rewrite(rqlst, rules)
+        self.assertEqual('Any SUM(SA) GROUPBY S WHERE P manifestation SA, P contributor S',
+                         rqlst.as_string())
+
+
+class RQLRelationRewriterTC(CubicWebTC):
+
+    appid = 'data/rewrite'
+
+    def test_base_rule(self):
+        with self.admin_access.client_cnx() as cnx:
+            art = cnx.create_entity('ArtWork', name=u'Les travailleurs de la Mer')
+            role = cnx.create_entity('Role', name=u'illustrator')
+            vic = cnx.create_entity('Person', name=u'Victor Hugo')
+            contrib = cnx.create_entity('Contribution', code=96, contributor=vic,
+                                        manifestation=art, role=role)
+            rset = cnx.execute('Any X WHERE X illustrator_of S')
+            self.assertEqual([u'Victor Hugo'],
+                             [result.name for result in rset.entities()])
+            rset = cnx.execute('Any S WHERE X illustrator_of S, X eid %(x)s',
+                               {'x': vic.eid})
+            self.assertEqual([u'Les travailleurs de la Mer'],
+                             [result.name for result in rset.entities()])
+
+
+def rule_rewrite(rqlst, kwargs=None):
+    rewriter = _prepare_rewriter(rqlrewrite.RQLRelationRewriter, kwargs)
+    rqlhelper.compute_solutions(rqlst.children[0], {'eid': eid_func_map},
+                                kwargs=kwargs)
+    rewriter.rewrite(rqlst)
+    for select in rqlst.children:
+        test_vrefs(select)
+    return rewriter.rewritten
+
+
+if __name__ == '__main__':
+    unittest_main()