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/**
* This function replaces the existing `setTimeout` and `setInterval` with wrappers that
* discount the `ms` passed in by `boost`.
*
* For example, if a module has:
*
* ```
* setTimeout(cb, 100);
* ```
*
* But a test has:
*
* ```
* useOverclockTimers(25);
* ```
*
* Then the module's call to `setTimeout` effectively becomes:
*
* ```
* setTimeout(cb, 4);
* ```
*
* It's important to note that the timing for `setTimeout` and order of execution is non-deterministic
* and discounting the `ms` passed could make this very obvious and expose some underlying issues
* with flaky failures.
*
* WARNING: If flaky spec failures show up in a spec that is using this helper, please consider either:
*
* - Refactoring the production code so that it's reactive to state changes, not dependent on timers.
* - Removing the call to this helper from the spec.
*
* @param {Number} boost
*/
export const useOverclockTimers = (boost = 50) => {
if (boost <= 0) {
throw new Error(`[overclock_timers] boost (${boost}) cannot be <= 0`);
}
let origSetTimeout;
let origSetInterval;
const newSetTimeout = (fn, msParam = 0) => {
const ms = msParam > 0 ? Math.floor(msParam / boost) : msParam;
return origSetTimeout(fn, ms);
};
const newSetInterval = (fn, msParam = 0) => {
const ms = msParam > 0 ? Math.floor(msParam / boost) : msParam;
return origSetInterval(fn, ms);
};
beforeEach(() => {
origSetTimeout = global.setTimeout;
origSetInterval = global.setInterval;
global.setTimeout = newSetTimeout;
global.setInterval = newSetInterval;
});
afterEach(() => {
global.setTimeout = origSetTimeout;
global.setInterval = origSetInterval;
});
};
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