Do not use expose election dummy vote in non election related unit te…

…sts (#4098)

* Do not use expose election dummy vote in non election related unit tests

Election objects always have one dummy vote in them, they never have
zero votes. However that is an implementation detail of the election
class, which should not be leaked outside.

By using votes_with_weights, we filter out that dummy votes, which always
has zero weight and we do not need to leak out its existence.

It also makes those unit tests easier to reason about. The dummy vote is
often a confusing complication.

* Fixed race condition where genesis private key was given too early

nano/core_test/node.cpp

@@ -3619,16 +3619,16 @@ TEST (node, rollback_vote_self)
 		// The write guard prevents the block processor from performing the rollback
 		auto write_guard = node.write_database_queue.wait (nano::writer::testing);
 
-		// Insert genesis key in the wallet
-		system.wallet (0)->insert_adhoc (nano::dev::genesis_key.prv);
-
-		ASSERT_EQ (1, election->votes ().size ());
+		ASSERT_EQ (0, election->votes_with_weight ().size ());
 		// Vote with key to switch the winner
 		election->vote (key.pub, 0, fork->hash ());
-		ASSERT_EQ (2, election->votes ().size ());
+		ASSERT_EQ (1, election->votes_with_weight ().size ());
 		// The winner changed
 		ASSERT_EQ (election->winner ()->hash (), fork->hash ());
 
+		// Insert genesis key in the wallet
+		system.wallet (0)->insert_adhoc (nano::dev::genesis_key.prv);
+
 		// Even without the rollback being finished, the aggregator must reply with a vote for the new winner, not the old one
 		ASSERT_TRUE (node.history.votes (send2->root (), send2->hash ()).empty ());
 		ASSERT_TRUE (node.history.votes (fork->root (), fork->hash ()).empty ());
@@ -3641,11 +3641,15 @@ TEST (node, rollback_vote_self)
 	}
 
 	// A vote is eventually generated from the local representative
-	ASSERT_TIMELY_EQ (5s, 3, election->votes ().size ());
-	auto votes = election->votes ();
-	auto vote = votes.find (nano::dev::genesis_key.pub);
-	ASSERT_NE (votes.end (), vote);
-	ASSERT_EQ (fork->hash (), vote->second.hash);
+	auto is_genesis_vote = [] (nano::vote_with_weight_info info) {
+		return info.representative == nano::dev::genesis_key.pub;
+	};
+	ASSERT_TIMELY_EQ (5s, 2, election->votes_with_weight ().size ());
+	auto votes_with_weight = election->votes_with_weight ();
+	ASSERT_EQ (1, std::count_if (votes_with_weight.begin (), votes_with_weight.end (), is_genesis_vote));
+	auto vote = std::find_if (votes_with_weight.begin (), votes_with_weight.end (), is_genesis_vote);
+	ASSERT_NE (votes_with_weight.end (), vote);
+	ASSERT_EQ (fork->hash (), vote->hash);
 }
 
 TEST (node, rollback_gap_source)