HTTP Date header time faking fails on Node 15.2.0 and later

HTTP Date header time is faked just fine up to Node v15.1.0 but fails with Node v15.2.0 or later.

• FakeTimers version : 6.0.1
• Environment : Node v15.5.0
• Other libraries you are using: assert, http

What did you expect to happen?

Should return HTTP Date header with fake time date: "Tue, 31 Dec 2013 23:59:59 GMT".

What actually happens

Instead returns HTTP Date header with current time, e.g. date: "Sun, 03 Jan 2021 17:22:52 GMT".

How to reproduce

Following is a minimal and complete mocha test case that reproduces the issue

import assert from "assert";
import http from "http";
import fake_timers from "@sinonjs/fake-timers";

describe("fake HTTP Date header time", function()
{
    let clock;
    let server;

    before(function(done)
    {
        clock = fake_timers.install({now: Date.parse("2013-12-31 23:59:59.123Z")});
        server = http.createServer((req, res) =>
        {
            req.on("data", () => void null);
            req.on("end", () =>
            {
                res.writeHead(200);
                res.end();
            });
        });
        server.listen(8080, done);
    });

    after(function(done)
    {
        clock.uninstall();
        server.close(done);
    });

    it("should fake HTTP Date header time", function(done)
    {
        const expectedHeaders =
        {
            "connection": "close",
            "date": "Tue, 31 Dec 2013 23:59:59 GMT",
            "transfer-encoding": "chunked"
        };
        const opts =
        {
            hostname: "localhost",
            method: "GET",
            path: "/",
            port: 8080
        };
        const req = http.request(opts, (res) =>
        {
            const {headers, statusCode, statusMessage} = res;
            res.on("data", () => void null);
            res.on("end", () =>
            {
                assert.strictEqual(statusCode, 200);
                assert.strictEqual(statusMessage, "OK");
                assert.deepStrictEqual(headers, expectedHeaders);
                done();
            });
        });
        req.end();
    });
});

Note

Starting with Node 15.2.0 http.js imports Date from primordials while Node 15.1.0 http.js just uses the global Date object.

[benjamingr]

Let’s see how it goes https://github.com/nodejs/node/pull/40733

[aduh95]

I quite like the flag idea as it gives to users the more power over how Node.js internals behave. What about a --expose-primordials flag? I think it would be easier to implement than a --no-primordials one, and would allow users to define a specific behaviour for Node.js internals without even changing the globals.