SomeCheckedException exception = new SomeCheckedException();
    assertSame(exception, Throwables.getRootCause(exception));
  }

  public void testGetRootCause_SingleWrapped() {
    SomeCheckedException cause = new SomeCheckedException();
    SomeChainingException exception = new SomeChainingException(cause);
    assertSame(cause, Throwables.getRootCause(exception));
  }

/**
 * Unit tests for {@link Runnables}.
 *
 * @author Olivier Pernet
 */
@GwtCompatible
public class RunnablesTest extends TestCase {
  public void testDoNothingRunnableIsSingleton() {
    assertSame(Runnables.doNothing(), Runnables.doNothing());
  }

    }
  }

  private static final String NON_NULL_STRING = "foo";

  public void testCheckNotNull_simple_success() {
    String result = Preconditions.checkNotNull(NON_NULL_STRING);
    assertSame(NON_NULL_STRING, result);
  }

  public void testCheckNotNull_simple_failure() {
    try {
      Preconditions.checkNotNull(null);
      fail("no exception thrown");

    RegularImmutableMap<Integer, Integer> map =
        (RegularImmutableMap<Integer, Integer>) builder.buildOrThrow();
    Object[] mapInternalArray = map.alternatingKeysAndValues;
    assertSame(builderArray, builderArrayAfterPuts);
    assertSame(builderArray, mapInternalArray);
  }

  public void testBuilder_orderEntriesByValue() {
    ImmutableMap<String, Integer> map =
        new Builder<String, Integer>()

      List<Entry<Object, Object>> warmed = warmUp(cache);
      for (int i = WARMUP_MIN; i < WARMUP_MAX; i++) {
        Entry<Object, Object> entry = warmed.get(i - WARMUP_MIN);
        Object newValue = new Object();
        assertSame(entry.getValue(), cache.asMap().put(entry.getKey(), newValue));
        // don't let the new entry get GCed
        warmed.add(entryOf(entry.getKey(), newValue));
        Object newKey = new Object();

  public void testToLowerCase() {
    assertEquals(LOWER, Ascii.toLowerCase(UPPER));
    assertSame(LOWER, Ascii.toLowerCase(LOWER));
    assertEquals(IGNORED, Ascii.toLowerCase(IGNORED));
    assertEquals("foobar", Ascii.toLowerCase("fOobaR"));
  }

  public void testToUpperCase() {
    assertEquals(UPPER, Ascii.toUpperCase(LOWER));
    assertSame(UPPER, Ascii.toUpperCase(UPPER));
    assertEquals(IGNORED, Ascii.toUpperCase(IGNORED));

  private static final String DATA1 = "data";

  public void testListenInPoolThreadReturnsSameFuture() throws Exception {
    ListenableFuture<String> listenableFuture = immediateFuture(DATA1);
    assertSame(listenableFuture, listenInPoolThread(listenableFuture));
  }

  private static class SingleCallListener implements Runnable {

    private boolean expectCall = false;

    assertUnboundedBelow(range);
    assertUnboundedAbove(range);
    assertFalse(range.isEmpty());
    assertEquals("(-\u221e..+\u221e)", range.toString());
    assertSame(range, reserializeAndAssert(range));
    assertSame(range, Range.all());
  }

  private static void assertUnboundedBelow(Range<Integer> range) {
    assertFalse(range.hasLowerBound());
    try {
      range.lowerEndpoint();

      threadUnexpectedException(t);
    }
  }

  /**
   * Just like assertSame(x, y), but additionally recording (using threadRecordFailure) any
   * AssertionFailedError thrown, so that the current testcase will fail.
   */
  public void threadAssertSame(Object x, Object y) {
    try {
      assertSame(x, y);
    } catch (AssertionFailedError t) {
      threadRecordFailure(t);
      throw t;
    }

    BadFuture badInput = new BadFuture(Futures.immediateFuture(20));
    ListenableFuture<String> chain = buildChainingFuture(badInput);
    ExecutionException e = assertThrows(ExecutionException.class, () -> chain.get());
    assertSame(RuntimeException.class, e.getCause().getClass());
  }

  /** Proxy to throw a {@link RuntimeException} out of the {@link #get()} method. */
  public static class BadFuture extends SimpleForwardingListenableFuture<Integer> {