package org.pojomatic.internal;
   
   import static org.testng.Assert.*;
   import org.testng.annotations.Test;
   import java.util.concurrent.atomic.AtomicBoolean;
   
   public class SelfPopulatingMapTest {
     /**
      * Test case which exposes a subtle threading bug
     * @throws Exception
     */
    @Test public void testThreading() throws Exception {
      final String token = "token";
      final SelfPopulatingMap<String, String> selfPopulatingMap =
        new SelfPopulatingMap<String, String>() {
        @Override protected String create(String key) {
          try {
            Thread.sleep(10); // ensure that two threads have time to collide.
          }
          catch (InterruptedException e) {}
          return new String(key);
        }
      };
  
      int numThreads = 2;
      Thread[] threads = new Thread[numThreads];
      final String[] results = new String[numThreads];
      for (int i = 0; i < threads.length; i++) {
        final int threadNumber = i;
        threads[i] = new Thread() {
          @Override public void run() {
            results[threadNumber] = selfPopulatingMap.get(token);
          }
        };
      }
      for (Thread t: threads) {
        t.start();
      }
      for (Thread t: threads) {
        t.join();
      }
      assertSame(results[1], results[0]);
    }
  
    @Test
    public void testBadConstructionFirstTime() {
      final AtomicBoolean firstTime = new AtomicBoolean(false);
      final SelfPopulatingMap<String, String> selfPopulatingMap =
        new SelfPopulatingMap<String, String>() {
        @Override protected String create(String key) {
          if (firstTime.getAndSet(true)) {
            return new String(key);
          }
          else {
            throw new RuntimeException("first");
          }
        }
      };
  
      try {
        selfPopulatingMap.get("x");
        fail("Exception expected");
      }
      catch(RuntimeException e) {
        assertEquals(e.getMessage(), "first");
      }
  
      assertEquals(selfPopulatingMap.get("x"), "x");
    }
  }