Add tests for exposed identifiers

Author: wooorm

test.js

@@ -6,8 +6,14 @@
 import assert from 'node:assert/strict'
 import test from 'node:test'
 import {isElement} from './index.js'
+import * as mod from './index.js'
 
 test('isElement', async (t) => {
+  const api = Object.keys(mod)
+  assert.ok(api.includes('isElement'), 'should expose `isElement`')
+  assert.ok(api.includes('convertElement'), 'should expose `convertElement`')
+  assert.equal(api.length, 2, 'should expose the public api')
+
   assert.equal(isElement(), false, 'should return `false` without node')
   assert.equal(isElement(null), false, 'should return `false` with `null`')