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