Execute event at an exact time in cypress - cypress

Question

I want my cypress test script to click a button as soon as the current time is past 20:00 UTC
I have a cron job on my server which triggers the e2e flow a few minutes before 20:00
So far so good, the test is being executed, I have a loop checking the time and waiting until 20:00 is reached, then hit the button and continue the test
for (let i = 0; i < 300; i++) {
currentHour = (new Date()).getUTCHours();
if(currentHour == 20)
{
cy.get(......).click();
break;
}
cy.wait(500);
}
But the way I understand cypress is built, new Date() always stays the same because all javascript is executed right away, so it contains the timestamp of test initialization...
I've been trying some stuff with cy.task, you can return a new date there but you can't use await to wait for that correct date retrieval since it doesn't return an acutal promise; more something from cypress itself
What else can I try? It seems an easy test but so hard to get exactly what I want

Answer 1

To make Cypress stay on the same date, you need to use cy.clock().
This command can be used to set the system to an exact date and time, but not allow the time to move forward until you issue the cy.tick() command.
It's hard to see what you are expecting to test, but this is how your test might look
cy.clock(new Date(2023, 2, 14, 19, 59, 30))
cy.visit('/')
// test something before the deadline
cy.tick(30_000)
cy.get(......).click()
// test something after the deadline

Answer 2

I couln't use clock as the time I am targetting is defined on server; the application only allows certain actions in a very small timeframe.
Found a solution though with the very use full Cypress wait until plugin
I created a task to get the actual date
cypress.config.js
const { defineConfig } = require("cypress");
module.exports = defineConfig({
e2e: {
setupNodeEvents(on, config) {
// implement node event listeners here
on('task', {
getCurrentHour() {
const date = new Date();
console.log(date + ' - ' + 'Checking current hour: ' + date.getUTCHours())
return date.getUTCHours();
}
})
},
},
});
spec.cy.ts
cy.waitUntil(() => cy.task("getCurrentHour").then(hour => hour === targetUTCHour), {timeout: 180000, // waits up to 2000 ms, default to 5000
interval: 1000});
// Execute code here
);