public static TestRunner of(Class taskClass) {
    Preconditions.checkNotNull(taskClass);
    Preconditions.checkState(
        StreamTask.class.isAssignableFrom(taskClass) || AsyncStreamTask.class.isAssignableFrom(taskClass));
    return new TestRunner(taskClass);
  }
Creates an instance of {@link TestRunner} for Low Level Samza Api
@param taskClass samza job extending either {@link StreamTask} or {@link AsyncStreamTask}
@return this {@link TestRunner}
samza-test/src/main/java/org/apache/samza/test/framework/TestRunner.java