It is a Jest-ism that shouldn't be in our open source package.
People using Jest can implement a similar pattern directly.
ReactTestUtils.Simulate = {};
  let eventType;
  for (eventType in EventPluginRegistry.eventNameDispatchConfigs) {
    /**
     * @param {!Element|ReactDOMComponent} domComponentOrNode
     * @param {?object} eventData Fake event data to use in SyntheticEvent.
     */
    ReactTestUtils.Simulate[eventType] = makeSimulator(eventType);
  }
}
const oldInjectEventPluginOrder =
  EventPluginHub.injection.injectEventPluginOrder;
EventPluginHub.injection.injectEventPluginOrder = function() {
  oldInjectEventPluginOrder.apply(this, arguments);
  buildSimulators();
};
const oldInjectEventPlugins = EventPluginHub.injection.injectEventPluginsByName;
EventPluginHub.injection.injectEventPluginsByName = function() {
  oldInjectEventPlugins.apply(this, arguments);