[test/web] fix invisibly bogus test (prepares #2755994)
The test was wrong but that was cancelled out by a cache effect and
fuzzy naming.
Wiping the entity caches restores sanity: the choices list are the
same before and after the SET.
Also field.choices uses entity.unrelated but always returns related +
unrelated elements.
Hence `choice` replaces `unrelated` where it makes sense.
AssertIn is used in place of AssertTrue.
from yams import schema2sql as y2sql
dbhelper = repo.system_source.dbhelper
rdefdef = schema['CWSource'].rdef('name')
attrtype = y2sql.type_from_constraints(dbhelper, rdefdef.object, rdefdef.constraints).split()[0]
cursor = session.cnxset['system']
sql('UPDATE entities SET asource = source WHERE asource is NULL')
dbhelper.change_col_type(cursor, 'entities', 'asource', attrtype, False)
dbhelper.change_col_type(cursor, 'entities', 'source', attrtype, False)
dbhelper.change_col_type(cursor, 'deleted_entities', 'source', attrtype, False)