Buggy time dependency in attack-cpu-background tests

[kgruszka]

Description/Context

Test assertion in attack-cpu-background randomly failed probably due to a buggy timer resolution:

describe('when the process takes some time to initialise', () => {
  it('waits', async () => {
    onFn.mockImplementationOnce((_msg, cb) => setTimeout(cb, 10));
    const attack = new BackgroundCPUAttack({ threads: 1 });
    const time = Date.now();
    await attack.start();
    expect(Date.now() - time).toBeGreaterThanOrEqual(10);
  });
});

It occurred once while I was developing locally and during the execution of GA. Sadly the job was rerun and the logs are lost.
I've executed the tests in a loop dozens of times and could not reproduce 🤔.

Expected behavior

I expect the tests to pass always if there is no bug in code.

Actual behavior

A single test that is dependant on time fails occasionally.

Code to reproduce

Hard to reproduce but just

npm t

Possible fix

Change test implementation to use mocked timers and avoid time dependency.

Checklist

• [👍] I have read the docs
• [👍] I'm using the latest version of Chaos Squirrel
• [👍] I'm willing to contribute a fix to this issue