ladybird/Libraries/LibJS/Tests/functions/function-length.js

test("basic functionality", () => {
  function foo() {}
  expect(foo).toHaveLength(0);
  expect((foo.length = 5)).toBe(5);
  expect(foo).toHaveLength(0);

  function bar(a, b, c) {}
  expect(bar).toHaveLength(3);
  expect((bar.length = 5)).toBe(5);
  expect(bar).toHaveLength(3);
});

test("functions with special parameter lists", () => {
  function baz(a, b = 1, c) {}
  expect(baz).toHaveLength(1);
  expect((baz.length = 5)).toBe(5);
  expect(baz).toHaveLength(1);

  function qux(a, b, ...c) {}
  expect(qux).toHaveLength(2);
  expect((qux.length = 2)).toBe(2);
  expect(qux).toHaveLength(2);
});