async function createServiceTester() {
  const servicePath = caller().replace('.tester.js', '.service.js')
  const ServiceClass = Object.values(await import(servicePath))[0]
  if (!(ServiceClass.prototype instanceof BaseService)) {
    throw Error(
      `${servicePath} does not export a single service. Invoke new ServiceTester() directly.`,
    )
  }
  return ServiceTester.forServiceClass(ServiceClass)
}
Automatically create a ServiceTester.

When run from e.g. `gem-rank.tester.js`, this will create a tester that
attaches to the service found in `gem-rank.service.js`.

This can't be used for `.service.js` files which export more than one
service.

@returns {module:core/service-test-runner/service-tester~ServiceTester}
   ServiceTester instance