wip: migrate to bun

test/isUndefined.spec.ts

@@ -0,0 +1,42 @@
+import assert from 'node:assert';
+import lodashStable from 'lodash';
+import { falsey, args, slice, symbol, realm } from './utils';
+import isUndefined from '../src/isUndefined';
+
+describe('isUndefined', () => {
+    it('should return `true` for `undefined` values', () => {
+        assert.strictEqual(isUndefined(), true);
+        assert.strictEqual(isUndefined(undefined), true);
+    });
+
+    it('should return `false` for non `undefined` values', () => {
+        const expected = lodashStable.map(falsey, (value) => value === undefined);
+
+        const actual = lodashStable.map(falsey, (value, index) =>
+            index ? isUndefined(value) : isUndefined(),
+        );
+
+        assert.deepStrictEqual(actual, expected);
+
+        assert.strictEqual(isUndefined(args), false);
+        assert.strictEqual(isUndefined([1, 2, 3]), false);
+        assert.strictEqual(isUndefined(true), false);
+        assert.strictEqual(isUndefined(new Date()), false);
+        assert.strictEqual(isUndefined(new Error()), false);
+        assert.strictEqual(isUndefined(slice), false);
+        assert.strictEqual(isUndefined({ a: 1 }), false);
+        assert.strictEqual(isUndefined(1), false);
+        assert.strictEqual(isUndefined(/x/), false);
+        assert.strictEqual(isUndefined('a'), false);
+
+        if (Symbol) {
+            assert.strictEqual(isUndefined(symbol), false);
+        }
+    });
+
+    it('should work with `undefined` from another realm', () => {
+        if (realm.object) {
+            assert.strictEqual(isUndefined(realm.undefined), true);
+        }
+    });
+});