assertNull(map.put(one, two));
    assertSame(two, map.get(one));
    map.putAll(ImmutableMap.of(two, three));
    assertSame(three, map.get(two));
    assertSame(two, map.putIfAbsent(one, three));
    assertSame(two, map.get(one));
    assertNull(map.putIfAbsent(three, one));
    assertSame(one, map.get(three));
    assertSame(two, map.replace(one, three));
    assertSame(three, map.get(one));

    assertFalse(Strings.isNullOrEmpty("a"));
  }

  public void testPadStart_noPadding() {
    assertSame("", Strings.padStart("", 0, '-'));
    assertSame("x", Strings.padStart("x", 0, '-'));
    assertSame("x", Strings.padStart("x", 1, '-'));
    assertSame("xx", Strings.padStart("xx", 0, '-'));
    assertSame("xx", Strings.padStart("xx", 2, '-'));
  }

  public void testPadStart_somePadding() {

    assertFalse(cache.asMap().containsValue(one));

    cache.put(one, two);

    assertSame(two, cache.getIfPresent(one));
    stats = cache.stats();
    assertEquals(2, stats.missCount());
    assertEquals(0, stats.loadSuccessCount());
    assertEquals(0, stats.loadExceptionCount());
    assertEquals(1, stats.hitCount());
    assertSame(two, cache.asMap().get(one));
    assertTrue(cache.asMap().containsKey(one));

    assertFalse(cache.asMap().containsValue(one));

    cache.put(one, two);

    assertSame(two, cache.getIfPresent(one));
    stats = cache.stats();
    assertEquals(2, stats.missCount());
    assertEquals(0, stats.loadSuccessCount());
    assertEquals(0, stats.loadExceptionCount());
    assertEquals(1, stats.hitCount());
    assertSame(two, cache.asMap().get(one));
    assertTrue(cache.asMap().containsKey(one));

    // more excruciating tests! Hooray!

    assertSame(CharMatcher.any(), CharMatcher.none().negate());
    assertSame(CharMatcher.none(), CharMatcher.any().negate());

    assertSame(WHATEVER, CharMatcher.any().and(WHATEVER));
    assertSame(CharMatcher.any(), CharMatcher.any().or(WHATEVER));

    assertSame(CharMatcher.none(), CharMatcher.none().and(WHATEVER));
    assertSame(WHATEVER, CharMatcher.none().or(WHATEVER));
  }

    // more excruciating tests! Hooray!

    assertSame(CharMatcher.any(), CharMatcher.none().negate());
    assertSame(CharMatcher.none(), CharMatcher.any().negate());

    assertSame(WHATEVER, CharMatcher.any().and(WHATEVER));
    assertSame(CharMatcher.any(), CharMatcher.any().or(WHATEVER));

    assertSame(CharMatcher.none(), CharMatcher.none().and(WHATEVER));
    assertSame(WHATEVER, CharMatcher.none().or(WHATEVER));
  }

          if (prev != null) {
            assertSame(prev, current.getPreviousInWriteQueue());
            assertSame(prev.getNextInWriteQueue(), current);
            assertThat(prev.getWriteTime()).isAtMost(current.getWriteTime());
          }
          Object key = current.getKey();
          if (key != null) {
            assertSame(current, segment.getEntry(key, current.getHash()));
          }

  public void testEmpty_comparator() {
    SortedSet<String> set = of();
    assertSame(Ordering.natural(), set.comparator());
  }

  public void testEmpty_headSet() {
    SortedSet<String> set = of();
    assertSame(set, set.headSet("c"));
  }

  public void testEmpty_tailSet() {
    SortedSet<String> set = of();
    assertSame(set, set.tailSet("f"));
  }

  public void testEmpty_subSet() {

    try {
      try {
        throw exception;
      } catch (Throwable e) {
        throw closer.rethrow(e);
      } finally {
        closer.close();
      }
    } catch (Throwable expected) {
      assertSame(exception, expected);
    }

    assertTrue(c1.isClosed());
    assertTrue(c2.isClosed());

    assertTrue(suppressor.suppressions.isEmpty());
  }

  public void testStrong_simplistic() {
    String canonical = "a";
    String not = new String("a");

    Interner<String> pool = Interners.newStrongInterner();
    assertSame(canonical, pool.intern(canonical));
    assertSame(canonical, pool.intern(not));
  }

  public void testStrong_null() {
    Interner<String> pool = Interners.newStrongInterner();