OpenTally/tests/special_cases.rs

/*  OpenTally: Open-source election vote counting
 *  Copyright © 2021 Lee Yingtong Li (RunasSudo)
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

mod utils;

use opentally::election::{CandidateState, CountState, Election};
use opentally::numbers::Rational;
use opentally::parser::blt;
use opentally::stv;
use opentally::ties::TieStrategy;

/// Insufficient candidates to fill all vacancies
#[test]
fn insufficient_candidates1() {
	let stv_opts = stv::STVOptionsBuilder::default()
		.ties(vec![TieStrategy::Random(String::new())])
		.build().unwrap();
	
	let mut election: Election<Rational> = blt::parse_path("tests/data/insufficient_candidates1.blt").expect("Syntax Error");
	stv::preprocess_election(&mut election, &stv_opts);
	
	let mut state = CountState::new(&election);
	
	stv::count_init(&mut state, &stv_opts).unwrap();
	
	loop {
		let result = stv::count_one_stage::<Rational>(&mut state, &stv_opts);
		match result {
			Ok(done) => { assert_eq!(done, false); }
			Err(err) => {
				assert_eq!(err, stv::STVError::CannotCompleteCount("Insufficient continuing candidates to complete count"));
				break;
			}
		}
	}
}

/// After bulk exclusion of candidates with no votes, insufficient candidates remain to fill all vacancies
#[test]
fn insufficient_candidates2() {
	let stv_opts = stv::STVOptionsBuilder::default()
		.ties(vec![TieStrategy::Random(String::new())])
		.build().unwrap();
	
	let mut election: Election<Rational> = blt::parse_path("tests/data/insufficient_candidates2.blt").expect("Syntax Error");
	stv::preprocess_election(&mut election, &stv_opts);
	
	let mut state = CountState::new(&election);
	
	stv::count_init(&mut state, &stv_opts).unwrap();
	
	loop {
		let result = stv::count_one_stage::<Rational>(&mut state, &stv_opts);
		match result {
			Ok(done) => { assert_eq!(done, false); }
			Err(err) => {
				assert_eq!(err, stv::STVError::CannotCompleteCount("Insufficient continuing candidates to complete count"));
				break;
			}
		}
	}
}

/// Tideman A33 election: exclusion of candidate with no votes; more candidates reach the quota than vacancies
#[test]
fn tideman_a33_ers97_rational() {
	let stv_opts = stv::STVOptionsBuilder::default()
		.round_surplus_fractions(Some(2))
		.round_values(Some(2))
		.round_votes(Some(2))
		.round_quota(Some(2))
		.quota(stv::QuotaType::DroopExact)
		.quota_criterion(stv::QuotaCriterion::GreaterOrEqual)
		.quota_mode(stv::QuotaMode::ERS97)
		.ties(vec![TieStrategy::Random(String::new("20210908"))])
		.surplus(stv::SurplusMethod::EG)
		.transferable_only(true)
		.exclusion(stv::ExclusionMethod::ByValue)
		.early_bulk_elect(false)
		.bulk_exclude(true)
		.defer_surpluses(true)
		.build().unwrap();
	
	let mut election: Election<Rational> = blt::parse_path("tests/data/A33.blt").expect("Syntax Error");
	stv::preprocess_election(&mut election, &stv_opts);
	
	let mut state = CountState::new(&election);
	
	stv::count_init(&mut state, &stv_opts).unwrap();
	
	loop {
		let result = stv::count_one_stage::<Rational>(&mut state, &stv_opts);
		match result {
			Ok(done) => { if done { break; } }
			Err(err) => { panic!("{}", err); }
		}
	}
	
	let num_winners = state.candidates.values().filter(|cc| cc.state == CandidateState::Elected).count();
	assert_eq!(num_winners, 3);
}