Change to match template better

test/index.ts

@@ -1,9 +1,16 @@
 import {expect} from 'chai';
-import {main} from '../src';
+import {SampleClass} from '../src';
 
 describe('index', () => {
   it('main', () => {
-    const res = main();
-    expect(res).to.be.deep.equal('Hello World');
+    const cls = new SampleClass();
+    const cases: [number, number, unknown][] = [
+      [2, 3, 5],
+      [2, 0, 2],
+      [500, -10, 490],
+    ];
+    for (const [a, b, res] of cases) {
+      expect(cls.add(a, b)).to.be.deep.equal(res);
+    }
   });
 });