referrer-policy.test.ts

import { check } from "./helpers";
import referrerPolicy from "../middlewares/referrer-policy";

describe("Referrer-Policy middleware", () => {
  it("sets header to no-referrer when passed no policy", async () => {
    await check(referrerPolicy(), {
      "referrer-policy": "no-referrer",
    });
    await check(referrerPolicy({}), {
      "referrer-policy": "no-referrer",
    });
    await check(referrerPolicy(Object.create(null)), {
      "referrer-policy": "no-referrer",
    });
    await check(referrerPolicy({ policy: undefined }), {
      "referrer-policy": "no-referrer",
    });
  });

  (
    [
      "no-referrer",
      "no-referrer-when-downgrade",
      "same-origin",
      "origin",
      "strict-origin",
      "origin-when-cross-origin",
      "strict-origin-when-cross-origin",
      "unsafe-url",
      "",
    ] as const
  ).forEach((policy) => {
    it(`can set the header to "${policy}" by specifying it as a string`, async () => {
      await check(referrerPolicy({ policy }), {
        "referrer-policy": policy,
      });
    });

    it(`can set the header to "${policy}" by specifying it as an array string`, async () => {
      await check(referrerPolicy({ policy: [policy] }), {
        "referrer-policy": policy,
      });
    });
  });

  it("can set an array with multiple values", async () => {
    await check(referrerPolicy({ policy: ["origin", "unsafe-url"] }), {
      "referrer-policy": "origin,unsafe-url",
    });
  });

  it("fails with a bad policy", () => {
    const invalidValues = [
      "foo",
      "sameorigin",
      "ORIGIN",
      123,
      false,
      null,
      {},
    ];
    for (const policy of invalidValues) {
      expect(referrerPolicy.bind(null, { policy: policy as any })).toThrow();
    }
  });

  it("fails with an empty array", () => {
    expect(referrerPolicy.bind(null, { policy: [] })).toThrow();
  });

  it("fails with duplicate values", () => {
    expect(
      referrerPolicy.bind(null, { policy: ["origin", "origin"] })
    ).toThrow();
    expect(
      referrerPolicy.bind(null, {
        policy: ["same-origin", "origin", "same-origin"],
      })
    ).toThrow();
  });
});