Path root = fs.getRootDirectories().iterator().next();
      assertNull(root.getParent());
      assertNull(root.toRealPath().getParent());
      MoreFiles.createParentDirectories(root); // test that there's no exception
    }
  }

  public void testCreateParentDirectories_relativePath() throws IOException {
    Path path = FS.getPath("nonexistent.file");
    assertNull(path.getParent());

        assertEquals(0, ByteConversionUtil.toPrimitiveByte(""));
    }

    /**
     * @throws Exception
     */
    public void testToByteForEmptyString() throws Exception {
        assertNull(ByteConversionUtil.toByte(""));
    }

        assertEquals(0, DoubleConversionUtil.toPrimitiveDouble(""), 0);
    }

    /**
     * @throws Exception
     */
    public void testToDoubleForEmptyString() throws Exception {
        assertNull(DoubleConversionUtil.toDouble(""));
    }

        assertEquals(0, FloatConversionUtil.toPrimitiveFloat(""), 0);
    }

    /**
     * @throws Exception
     */
    public void testToFloatForEmptyString() throws Exception {
        assertNull(FloatConversionUtil.toFloat(""));
    }

    assertEquals(0, queue.size());

    assertFalse(queue.remove("hi"));
    assertEquals(0, queue.size());

    assertThrows(NoSuchElementException.class, () -> queue.element());

    assertNull(queue.peek());
    assertNull(queue.poll());
    assertThrows(NoSuchElementException.class, () -> queue.remove());
  }

  public void testRemainingCapacity_maxSize0() {
    EvictingQueue<String> queue = EvictingQueue.create(0);

    assertTrue(future.isCancelled());
  }

  public void testAwaitClear() {
    final WeakReference<Object> ref = new WeakReference<>(new Object());
    GcFinalization.awaitClear(ref);
    assertNull(ref.get());
  }

  public void testAwaitDone_finalizationPredicate() {
    final WeakHashMap<Object, Object> map = new WeakHashMap<>();
    map.put(new Object(), Boolean.TRUE);
    GcFinalization.awaitDone(

    assertEquals("", Strings.nullToEmpty(null));
    assertEquals("", Strings.nullToEmpty(""));
    assertEquals("a", Strings.nullToEmpty("a"));
  }

  public void testEmptyToNull() {
    assertNull(Strings.emptyToNull(null));
    assertNull(Strings.emptyToNull(""));
    assertEquals("a", Strings.emptyToNull("a"));
  }

  public void testIsNullOrEmpty() {
    assertTrue(Strings.isNullOrEmpty(null));

    assertEquals("dollar", bimap2.get(Currency.DOLLAR));
    assertEquals(bimap1, bimap2);
    bimap2.inverse().put("franc", Currency.FRANC);
    assertEquals("franc", bimap2.get(Currency.FRANC));
    assertNull(bimap1.get(Currency.FRANC));
    assertFalse(bimap2.equals(bimap1));

    /* Test that it can be empty. */
    EnumHashBiMap<Currency, String> emptyBimap = EnumHashBiMap.create(Currency.class);

        final ResponseData responseData = fsClient.doHead("file:" + path);
        assertNotNull(responseData.getLastModified());
        assertTrue(responseData.getLastModified().getTime() < new Date().getTime());
        assertNull(responseData.getResponseBody());
    }

    public void test_doHead_dir() throws Exception {
        final File file = ResourceUtil.getResourceAsFile("test");
        String path = file.getAbsolutePath();

        ComponentUtil.setFessConfig(null);
        super.tearDown();
    }

    public void test_evaluate() {
        final Map<String, Object> params = new HashMap<>();
        assertNull(groovyEngine.evaluate("", params));
        assertEquals("", groovyEngine.evaluate("return ''", params));
        assertEquals(1, groovyEngine.evaluate("return 1", params));

        params.put("test", "123");