Add simple test to ensure app launches properly

tests/index.test.js

@@ -0,0 +1,20 @@
+describe("YouTube Music App", () => {
+	const app = global.__APP__;
+
+	test("With default settings, app is launched and visible", async () => {
+		expect(app.isRunning()).toBe(true);
+
+		const win = app.browserWindow;
+
+		const isVisible = await win.isVisible();
+		expect(isVisible).toBe(true);
+
+		const { width, height } = await win.getBounds();
+		expect(width).toBeGreaterThan(0);
+		expect(height).toBeGreaterThan(0);
+
+		const { client } = app;
+		const title = await client.getTitle();
+		expect(title).toEqual("YouTube Music");
+	});
+});