ladybird/Libraries/LibJS/Tests/builtins/JSON/JSON.stringify.js

describe("correct behavior", () => {
  test("length", () => {
    expect(JSON.stringify).toHaveLength(3);
  });

  test("basic functionality", () => {
    [
      [5, "5"],
      [undefined, undefined],
      [null, "null"],
      [NaN, "null"],
      [-NaN, "null"],
      [Infinity, "null"],
      [-Infinity, "null"],
      [true, "true"],
      [false, "false"],
      ["test", '"test"'],
      [new Number(5), "5"],
      [new Boolean(false), "false"],
      [new String("test"), '"test"'],
      [() => {}, undefined],
      [[1, 2, "foo"], '[1,2,"foo"]'],
      [{ foo: 1, bar: "baz", qux() {} }, '{"foo":1,"bar":"baz"}'],
      [
        {
          var1: 1,
          var2: 2,
          toJSON(key) {
            let o = this;
            o.var2 = 10;
            return o;
          },
        },
        '{"var1":1,"var2":10}',
      ],
    ].forEach(testCase => {
      expect(JSON.stringify(testCase[0])).toEqual(testCase[1]);
    });
  });

  test("ignores non-enumerable properties", () => {
    let o = { foo: "bar" };
    Object.defineProperty(o, "baz", { value: "qux", enumerable: false });
    expect(JSON.stringify(o)).toBe('{"foo":"bar"}');
  });
});

describe("errors", () => {
  test("cannot serialize BigInt", () => {
    expect(() => {
      JSON.stringify(5n);
    }).toThrow(TypeError, "Cannot serialize BigInt value to JSON");
  });

  test("cannot serialize circular structures", () => {
    let bad1 = {};
    bad1.foo = bad1;
    let bad2 = [];
    bad2[5] = [[[bad2]]];

    let bad3a = { foo: "bar" };
    let bad3b = [1, 2, bad3a];
    bad3a.bad = bad3b;

    [bad1, bad2, bad3a].forEach(bad => {
      expect(() => {
        JSON.stringify(bad);
      }).toThrow(TypeError, "Cannot stringify circular object");
    });
  });
});