build: add jest, tests

tests/isDeepWeakEqual.test.ts

@@ -0,0 +1,15 @@
+import { isDeepWeakEqual } from "../src";
+import { expect, test } from "@jest/globals";
+
+test("weakly compares objects", () => {
+  expect(isDeepWeakEqual({ a: 1 }, ["lorem"])).toBe(false);
+
+  expect(isDeepWeakEqual({ a: 1 }, { a: 1 })).toBe(true);
+
+  expect(
+    isDeepWeakEqual(
+      { date: "2024-03-12T18:19:50.548Z" },
+      { date: new Date(1710267590548) },
+    ),
+  ).toBe(true);
+});