Add a test for self-damage critical hits (#4954)

test/simulator/misc/critical.js

@@ -0,0 +1,21 @@
+'use strict';
+
+const assert = require('./../../assert');
+const common = require('./../../common');
+
+let battle;
+
+describe('Critical hits', function () {
+	afterEach(function () {
+		battle.destroy();
+	});
+
+	it('should not happen on self-hits', function () {
+		battle = common.createBattle();
+		battle.join('p1', 'Guest 1', 1, [{species: "Zubat", moves: ['confuseray']}]);
+		battle.join('p2', 'Guest 2', 1, [{species: "Chansey", item: 'luckypunch', ability: 'superluck', moves: ['softboiled']}]);
+		battle.makeChoices('move confuseray', 'move softboiled');
+		assert(battle.log.some(line => line.includes('[from] confusion')));
+		assert(battle.log.every(line => !line.startsWith('|-crit')));
+	});
+});