package com.iluwatar.lazy.loading;

import org.junit.Test;

import java.lang.reflect.Field;

import static org.junit.Assert.assertNotNull;
import static org.junit.Assert.assertNull;

/**
 * Using reflection this test shows that the heavy field is not instantiated until the method
 * getHeavy is called
 *
 * Created by jones on 11/10/2015.
 */
public class HolderThreadSafeTest {

  @Test
  public void test() throws IllegalAccessException {
    HolderThreadSafe hts = new HolderThreadSafe();

    {
      // first call is null
      Field[] ff = HolderThreadSafe.class.getDeclaredFields();
      for (Field f : ff) {
        f.setAccessible(true);
      }

      assertNull(ff[0].get(hts));
    }

    // now it is lazily loaded
    hts.getHeavy();

    {
      // now it is not null - call via reflection so that the test is the same before and after
      Field[] ff = HolderThreadSafe.class.getDeclaredFields();
      for (Field f : ff) {
        f.setAccessible(true);
      }

      assertNotNull(ff[0].get(hts));
    }
  }
}