How to use the @aurelia/validation.ValidationConfiguration.customize function in @aurelia/validation

async function runTest(
    testFunction: TestFunction,
    { template, customDefaultTrigger }: TestSetupContext
  ) {
    const ctx = TestContext.createHTMLTestContext();
    const container = ctx.container;
    const host = ctx.dom.createElement('app');
    ctx.doc.body.appendChild(host);
    let app;
    const au = new Aurelia(container);
    await au
      .register(
        customDefaultTrigger
          ? ValidationConfiguration.customize((options) => {
            options.defaultTrigger = customDefaultTrigger;
          })
          : ValidationConfiguration
      )
      .app({
        host,
        component: app = (() => {
          const ca = CustomElement.define({ name: 'app', isStrictBinding: true, template }, App);
          return new ca(container);
        })()
      })
      .start()
      .wait();

    await testFunction({ app, container, host });

function setup(validator?: Class) {
    const container = DI.createContainer();
    container.register(
      validator
        ? ValidationConfiguration.customize((options) => {
          options.validator = validator;
        })
        : ValidationConfiguration);
    return { sut: container.get(IValidator), container };
  }

function setup(customMessages?: ICustomMessage[]) {
    const container = TestContext.createHTMLTestContext().container;
    const eventLog = new EventLog();

    const configuration = customMessages !== (void 0)
      ? ValidationConfiguration.customize((options) => {
        options.customMessages = customMessages;
      })
      : ValidationConfiguration;
    container.register(
      configuration,
      Registration.instance(ISink, eventLog)
    );
    return {
      sut: container.get(IValidationMessageProvider),
      container,
      eventLog
    };
  }