test(js): add vitest

app/javascript/shared/utils.test.ts

@@ -0,0 +1,29 @@
+import { suite, test, expect } from 'vitest';
+
+import { show, hide, toggle } from './utils';
+
+suite('@utils', () => {
+  test('show', () => {
+    const input = document.createElement('input');
+    input.classList.add('hidden');
+
+    show(input);
+    expect(input.classList.contains('hidden')).toBeFalsy();
+  });
+
+  test('hide', () => {
+    const input = document.createElement('input');
+
+    hide(input);
+    expect(input.classList.contains('hidden')).toBeTruthy();
+  });
+
+  test('toggle', () => {
+    const input = document.createElement('input');
+
+    toggle(input);
+    expect(input.classList.contains('hidden')).toBeTruthy();
+    toggle(input);
+    expect(input.classList.contains('hidden')).toBeFalsy();
+  });
+});