Implement EV guesser test

Also improve existing battle test.

src/battle-dex-data.ts

@@ -1305,6 +1305,7 @@ if (typeof require === 'function') {
 	// in Node
 	(global as any).BattleBaseSpeciesChart = BattleBaseSpeciesChart;
 	(global as any).BattleStats = BattleStats;
+	(global as any).BattleNatures = BattleNatures;
 	(global as any).PureEffect = PureEffect;
 	(global as any).Template = Template;
 	(global as any).Ability = Ability;

src/battle-tooltips.ts

@@ -2160,3 +2160,8 @@ class BattleStatGuesser {
 		return Math.floor(val);
 	}
 }
+
+if (typeof require === 'function') {
+	// in Node
+	(global as any).BattleStatGuesser = BattleStatGuesser;
+}

test/battle.test.js

@@ -1,9 +1,5 @@
-const fs = require('fs');
-const path = require('path');
 const assert = require('assert').strict;
 
-process.chdir(path.resolve(__dirname, '..'));
-
 window = global;
 
 require('../js/battle-dex-data.js');

test/ev-guesser.test.js

@@ -0,0 +1,22 @@
+const assert = require('assert').strict;
+
+try {
+  global.BattlePokedex = require('../data/pokedex.js').BattlePokedex;
+} catch (err) {}
+require('../js/battle-dex-data.js');
+require('../js/battle-dex.js');
+require('../js/battle-tooltips.js');
+
+describe('EV Guesser', () => {
+
+  (global.BattlePokedex ? it : it.skip)('should guess well', () => {
+    const guesser = new BattleStatGuesser('gen7ou');
+    let guess = guesser.guess({
+      species: 'Arcanine',
+      item: 'Choice Band',
+      moves: ['Flare Blitz', 'Close Combat', 'Wild Charge', 'Extreme Speed'],
+    });
+    assert(guess.role === 'Fast Band');
+  });
+
+});