def test_arbitrary_decision_provided(app):
c = [
Candidate("C0"),
Candidate("C1"),
Candidate("C2"),
Candidate("C3"),
]
ballots = [
Ballot(preference=[c[0]]),
Ballot(preference=[c[1]]),
Ballot(preference=[c[2]]),
Ballot(preference=[c[3]]),
Ballot(preference=[c[3]]),
]
arbitrary_discards = [
[c[0], c[1]],
]
tally = Tally(ballots=ballots, arbitrary_discards=arbitrary_discards)
elected, discarded, rejected = tally.run()
assert set(elected) == {c[3]}
assert set(discarded) == {c[0], c[1], c[2]}
assert set(rejected) == set()
def test_multi_vacancy_vote_transfer_scenario_enough(app):
c = [
Candidate("C0"),
Candidate("C1"),
Candidate("C2"),
Candidate("C3"),
]
ballots = [
Ballot(preference=[c[0], c[2]]),
Ballot(preference=[c[0], c[2]]),
Ballot(preference=[c[0], c[2]]),
Ballot(preference=[c[0], c[2]]),
Ballot(preference=[c[0], c[2]]),
Ballot(preference=[c[0], c[3]]),
Ballot(preference=[c[1]]),
Ballot(preference=[c[1]]),
Ballot(preference=[c[1]]),
Ballot(preference=[c[2]]),
]
tally = Tally(ballots=ballots, vacancies=2)
elected, discarded, rejected = tally.run()
assert set(elected) == {c[0], c[2]}
assert set(discarded) == {c[1], c[3]}
assert set(rejected) == set()
def test_tally_with_mutual_rejection_paradox(app, feature_flags):
feature_flags.enable(FEATURE_STV_REJECTION)
c = [
Candidate("C0"),
Candidate("C1"),
Candidate("C2"),
]
ballots = [
Ballot(preference=[c[0]], reject=[c[1]]),
Ballot(preference=[c[0]], reject=[c[1]]),
Ballot(preference=[c[0]], reject=[c[1]]),
Ballot(preference=[c[1]], reject=[c[0]]),
Ballot(preference=[c[1]], reject=[c[0]]),
Ballot(preference=[c[1]], reject=[c[0]]),
Ballot(preference=[c[0], c[1], c[2]]),
]
tally = Tally(ballots=ballots)
elected, discarded, rejected = tally.run()
assert set(elected) == {c[2]}
assert set(discarded) == set()
assert set(rejected) == {c[0], c[1]}
def test_single_candidate_with_zero_score(app):
c = [
Candidate("C0"),
]
ballots = []
tally = Tally(ballots=ballots, candidates=c)
elected, discarded, rejected = tally.run()
assert set(elected) == set()
assert set(discarded) == {c[0]}
assert set(rejected) == set()
def test_single_candidate_with_zero_score_3(app):
c = [
Candidate("C0"),
Candidate("C1"),
]
ballots = [
Ballot(preference=[c[1]]),
]
tally = Tally(ballots=ballots, candidates=c, vacancies=2)
elected, discarded, rejected = tally.run()
assert set(elected) == {c[1]}
assert set(discarded) == {c[0]}
assert set(rejected) == set()
def test_tally_with_single_ballot(app):
c = [
Candidate("C0"),
Candidate("C1"),
Candidate("C2"),
]
ballots = [
Ballot(preference=[c[0], c[1], c[2]]),
]
tally = Tally(ballots=ballots)
elected, discarded, rejected = tally.run()
assert set(elected) == {c[0]}
assert set(discarded) == {c[1], c[2]}
assert set(rejected) == set()
def test_arbitrary_decision_needed(app):
c = [
Candidate("C0"),
Candidate("C1"),
Candidate("C2"),
Candidate("C3"),
]
ballots = [
Ballot(preference=[c[0]]),
Ballot(preference=[c[1]]),
Ballot(preference=[c[2]]),
Ballot(preference=[c[3]]),
Ballot(preference=[c[3]]),
]
tally = Tally(ballots=ballots)
with raises(ArbitraryDiscardDecisionNeededError):
tally.run()
def test_multi_vacancy_tally_with_single_ballot(app):
c = [
Candidate("C0"),
Candidate("C1"),
Candidate("C2"),
Candidate("C3"),
Candidate("C4"),
]
ballots = [
Ballot(preference=[c[3], c[1], c[4], c[2], c[0]]),
]
tally = Tally(ballots=ballots, vacancies=3)
elected, discarded, rejected = tally.run()
assert set(elected) == {c[1], c[3], c[4]}
assert set(discarded) == {c[0], c[2]}
assert set(rejected) == set()
def test_tally_simple_run_002(app):
c = [
Candidate("C0"),
Candidate("C1"),
Candidate("C2"),
]
ballots = [
Ballot(preference=[c[0]]),
Ballot(preference=[c[0]]),
Ballot(preference=[c[1]]),
]
tally = Tally(ballots=ballots)
elected, discarded, rejected = tally.run()
assert set(elected) == {c[0]}
assert set(discarded) == {c[1]}
assert set(rejected) == set()
def get_position_scores(position):
candidates = [
Candidate(id=candidate.id) for candidate in position.candidates
]
arbitrary_discards = []
for discard in position.arbitrary_discards:
candidates_to_discard = [
Candidate(id=candidate.id) for candidate in discard.discarded
]
arbitrary_discards.append(candidates_to_discard)
ballots = set()
for vote in position.votes.all():
preference = [Candidate(id=kmsid) for kmsid in vote.preference]
reject = {Candidate(id=kmsid) for kmsid in vote.reject}
ballots.add(Ballot(preference, reject))
vacancies = 1 if position.name == POSITION_BOSS else 3
return Tally(ballots,
vacancies,
candidates=candidates,
arbitrary_discards=arbitrary_discards).count_votes()
def reckon_position(position, reckon_again=False):
log.info(f'Reckoning position {position}')
if not position.is_reckoned or reckon_again:
log.info(f'Position not yet reckoned {position}')
candidates = [
Candidate(id=candidate.id) for candidate in position.candidates
]
arbitrary_discards = []
for discard in position.arbitrary_discards:
candidates_to_discard = [
Candidate(id=candidate.id) for candidate in discard.discarded
]
arbitrary_discards.append(candidates_to_discard)
log.debug(f'candidates = {candidates}')
ballots = set()
for vote in position.votes.all():
log.debug(f'Processing vote {vote}')
log.debug(f'vote.preference = {vote.preference}')
log.debug(f'vote.reject = {vote.reject}')
preference = [Candidate(id=kmsid) for kmsid in vote.preference]
reject = {Candidate(id=kmsid) for kmsid in vote.reject}
ballots.add(Ballot(preference, reject))
vacancies = 1 if position.name == POSITION_BOSS else 3
try:
elected_candidates, discarded_candidates, rejected_candidates = Tally(
ballots,
vacancies,
candidates=candidates,
arbitrary_discards=arbitrary_discards).run()
except ArbitraryDiscardDecisionNeededError as e:
e.position = position
for candidate in e.candidates:
candidate.fellow = Fellow.query.filter_by(
id=candidate.id).first()
raise e
elected_fellows = [
Fellow.query.filter_by(id=candidate.id).first()
for candidate in elected_candidates
]
discarded_fellows = [
Fellow.query.filter_by(id=candidate.id).first()
for candidate in discarded_candidates
]
rejected_fellows = [
Fellow.query.filter_by(id=candidate.id).first()
for candidate in rejected_candidates
]
if position.name == POSITION_FREE:
election = position.election
for p in election.positions.all():
if p.name not in (POSITION_BOSS, POSITION_FREE,
POSITION_COVISION):
elected, _, _ = reckon_position(p)
elected_fellows.extend(elected)
position.elected = elected_fellows
position.discarded = discarded_fellows
position.rejected = rejected_fellows
position.is_reckoned = True
db.session.commit()
elected = position.elected.order_by(Fellow.surname.asc(),
Fellow.name.asc()).all()
discarded = position.discarded.order_by(Fellow.surname.asc(),
Fellow.name.asc()).all()
rejected = position.rejected.order_by(Fellow.surname.asc(),
Fellow.name.asc()).all()
return elected, discarded, rejected