1 files changed, 65 insertions, 0 deletions
diff --git a/spec/frontend_integration/test_helpers/utils/overclock_timers.js b/spec/frontend_integration/test_helpers/utils/overclock_timers.js
new file mode 100644
index 00000000000..046c7f8e527
--- /dev/null
+++ b/spec/frontend_integration/test_helpers/utils/overclock_timers.js
@@ -0,0 +1,65 @@
+/**
+ * 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
+ */
+// eslint-disable-next-line import/prefer-default-export
+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;
+  });
+};