From 1e2f74e60bf7d23a581650242c43a5457cb840a2 Mon Sep 17 00:00:00 2001
From: RunasSudo <runassudo@yingtongli.me>
Date: Fri, 15 Jan 2021 16:00:22 +1100
Subject: [PATCH] Fix bug where withdrawn candidates would interfere with bulk
 exclusion, etc. logic

---
 pyRCV2/method/base_stv.py  | 8 +++++---
 tests/test_aec.py          | 1 +
 tests/test_combinations.py | 5 ++++-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/pyRCV2/method/base_stv.py b/pyRCV2/method/base_stv.py
index c80012c..4ff1c6e 100644
--- a/pyRCV2/method/base_stv.py
+++ b/pyRCV2/method/base_stv.py
@@ -66,12 +66,14 @@ class BaseSTVCounter:
 		self.step_results = []
 		self.num_elected = 0
 		self.num_excluded = 0
+		self.num_withdrawn = 0
 		
 		# Withdraw candidates
 		for candidate in self.election.withdrawn:
 			__pragma__('opov')
 			self.candidates[candidate].state = CandidateState.WITHDRAWN
 			__pragma__('noopov')
+			self.num_withdrawn += 1
 	
 	def reset(self):
 		"""
@@ -177,7 +179,7 @@ class BaseSTVCounter:
 		# Are there just enough candidates to fill all the seats?
 		if self.options['bulk_elect']:
 			# Include EXCLUDING to avoid interrupting an exclusion
-			if len(self.election.candidates) - self.num_excluded + sum(1 for c, cc in self.candidates.items() if cc.state == CandidateState.EXCLUDING) <= self.election.seats:
+			if len(self.election.candidates) - self.num_withdrawn - self.num_excluded + sum(1 for c, cc in self.candidates.items() if cc.state == CandidateState.EXCLUDING) <= self.election.seats:
 				# Declare elected all remaining candidates
 				candidates_elected = [(c, cc) for c, cc in self.candidates.items() if cc.state == CandidateState.HOPEFUL]
 				if len(candidates_elected) == 1:
@@ -295,7 +297,7 @@ class BaseSTVCounter:
 		
 		# If we did not perform bulk election in before_surpluses: Are there just enough candidates to fill all the seats?
 		if not self.options['bulk_elect']:
-			if len(self.election.candidates) - self.num_excluded <= self.election.seats:
+			if len(self.election.candidates) - self.num_withdrawn - self.num_excluded <= self.election.seats:
 				# Declare elected one remaining candidate at a time
 				hopefuls = [(c, cc) for c, cc in self.candidates.items() if cc.state == CandidateState.HOPEFUL]
 				hopefuls.sort(key=lambda x: x[1].votes, reverse=True)
@@ -367,7 +369,7 @@ class BaseSTVCounter:
 		Returns List[Tuple[Candidate, CountCard]]
 		"""
 		
-		remaining_candidates = len(self.election.candidates) - self.num_excluded
+		remaining_candidates = len(self.election.candidates) - self.num_withdrawn - self.num_excluded
 		__pragma__('opov')
 		total_surpluses = sum((cc.votes - self.quota for c, cc in self.candidates.items() if cc.votes > self.quota), Num(0))
 		__pragma__('noopov')
diff --git a/tests/test_aec.py b/tests/test_aec.py
index 72ea757..029ff45 100644
--- a/tests/test_aec.py
+++ b/tests/test_aec.py
@@ -47,6 +47,7 @@ def test_aec_tas19():
 	counter = UIGSTVCounter(election, {
 		'surplus_order': 'order',
 		'exclusion': 'by_value',
+		'bulk_exclude': True,
 		'round_quota': 0,
 		'round_votes': 0,
 	})
diff --git a/tests/test_combinations.py b/tests/test_combinations.py
index 17c429f..b938285 100644
--- a/tests/test_combinations.py
+++ b/tests/test_combinations.py
@@ -59,6 +59,9 @@ def maketst(numbers, counter_cls, options, options_description):
 	return t_py, t_js
 
 test_prsa1_scottish_py, test_prsa1_scottish_js = maketst('Fixed', 'pyRCV2.method.gregory.WIGSTVCounter', {'round_quota': 0}, '--round-quota 0')
-test_prsa1_senate_py, test_prsa1_senate_js = maketst('Fixed', 'pyRCV2.method.gregory.UIGSTVCounter', {'surplus_order': 'order', 'exclusion': 'by_value', 'round_quota': 3, 'round_votes': 3, 'round_tvs': 3, 'round_weights': 3}, '--method uig --round-quota 3 --round-votes 3 --round-tvs 3 --round-weights 3 --surplus-order order --exclusion by_value')
+test_prsa1_senate_py, test_prsa1_senate_js = maketst('Fixed', 'pyRCV2.method.gregory.UIGSTVCounter', {'surplus_order': 'order', 'exclusion': 'by_value', 'bulk_exclude': True, 'round_quota': 0, 'round_votes': 0}, '--method uig --bulk-exclude --round-quota 0 --round-votes 0 --surplus-order order --exclusion by_value')
 test_prsa1_meek_py, test_prsa1_meek_js = maketst('Fixed', 'pyRCV2.method.meek.MeekSTVCounter', {'quota_criterion': 'gt', 'quota': 'droop_exact', 'quota_mode': 'progressive'}, '--method meek --quota droop_exact --quota-criterion gt --quota-mode progressive')
 test_prsa1_wright_py, test_prsa1_wright_js = maketst('Fixed', 'pyRCV2.method.gregory.WIGSTVCounter', {'exclusion': 'wright', 'round_quota': 0, 'bulk_exclude': True}, '--bulk-exclude --round-quota 0 --exclusion wright')
+
+# Regression test: Withdrawn candidates interfering with bulk exclusion
+test_meekm_senate_py, test_meekm_senate_js = maketst('Fixed', 'pyRCV2.method.gregory.UIGSTVCounter', {'surplus_order': 'order', 'exclusion': 'by_value', 'bulk_exclude': True, 'round_quota': 0, 'round_votes': 0}, '--method uig --bulk-exclude --round-quota 0 --round-votes 0 --surplus-order order --exclusion by_value')