* Sets a converter for dates.
     *
     * @param pattern
     *            The date pattern. Must not be {@literal null} or an empty string.
     * @param propertyNames
     *            The property names to which this converter will be applied. Each element must not be {@literal null} or an empty string.
     * @return This instance itself
     * @see DateConverter
     */

        // Mock successful but empty response
        when(treeHandle.send(any(), any(), (RequestParam[]) any())).thenAnswer(invocation -> {
            // The response is the second argument
            Object response = invocation.getArgument(1);
            // Return it unchanged (which will have default values = empty results)
            return response;
        });

    }

    public void test_search_withEmptyQuery() {
        // Test search with empty query
        TestRankFusionSearcher testSearcher = new TestRankFusionSearcher();
        String query = "";
        SearchRequestParams params = createTestSearchRequestParams();
        OptionalThing<FessUserBean> userBean = OptionalThing.empty();

        SearchResult result = testSearcher.search(query, params, userBean);

            pacString.check(testString);
        }, "A PACDecodingException should be thrown for a non-empty string with a zero pointer.");

        // Verify the exception message
        assertEquals("Non-empty string", exception.getMessage(), "The exception message is not correct.");
    }

    /**

     *
     * @param date the date to format
     * @return formatted date string, or empty string if date is null
     */
    public static String formatDate(final Date date) {
        if (date == null) {
            return StringUtil.EMPTY;
        }
        final SimpleDateFormat sdf = new SimpleDateFormat(Constants.ISO_DATETIME_FORMAT);

  private val headers: Headers = Headers.EMPTY

  @Test fun testIPv4() {
    val socket =
      MockWebServerSocket(
        FakeSocket(
          localAddress = InetAddress.getByAddress("127.0.0.1", byteArrayOf(127, 0, 0, 1)),
          localPort = 80,
        ),
      )
    val request = RecordedRequest(DEFAULT_REQUEST_LINE_HTTP_1, headers, emptyList(), 0, ByteString.EMPTY, 0, 0, socket)

    private void validateIdentity() {
        if (empty(groupId)) {
            throw new InvalidArtifactRTException(
                    groupId, artifactId, getVersion(), type, "The groupId cannot be empty.");
        }

        if (empty(artifactId)) {
            throw new InvalidArtifactRTException(
                    groupId, artifactId, getVersion(), type, "The artifactId cannot be empty.");
        }

        if (empty(type)) {

            }
        }

        // An empty file should return no items
        assertEquals("Empty file should have no items", 0, result.size());
        assertEquals("Empty file should have no records", 0, result.getAllRecordCount());
        assertEquals("Empty file should have no pages", 0, result.getAllPageCount());
    }

    // Test selectList method with valid data

     *
     * @param u the URL string to extract host from
     * @return the host name, or empty string if URL is blank, or unknown hostname if parsing fails
     */
    default String getHost(final String u) {
        if (StringUtil.isBlank(u)) {
            return StringUtil.EMPTY; // empty
        }

        String url = u;
        final String originalUrl = url;

        int idx = url.indexOf("://");

     *            The property name. Must not be {@literal null} or empty string
     * @return Whether the {@link PropertyDesc} exists
     */
    boolean hasPropertyDesc(String propertyName);

    /**
     * Returns the {@link PropertyDesc}.
     *
     * @param propertyName
     *            The property name. Must not be {@literal null} or empty string
     * @return {@link PropertyDesc}
     */