* @author Kevin Bourrillion
 */
@NullMarked
@GwtCompatible
public class StringsTest extends TestCase {
  public void testNullToEmpty() {
    assertEquals("", Strings.nullToEmpty(null));
    assertEquals("", Strings.nullToEmpty(""));
    assertEquals("a", Strings.nullToEmpty("a"));
  }

  public void testEmptyToNull() {
    assertNull(Strings.emptyToNull(null));
    assertNull(Strings.emptyToNull(""));

   *
   * @param string the string to test and possibly return
   * @return {@code string} itself if it is non-null; {@code ""} if it is null
   */
  public static String nullToEmpty(@Nullable String string) {
    return Platform.nullToEmpty(string);
  }

  /**
   * Returns the given string if it is nonempty; {@code null} otherwise.
   *
   * @param string the string to test and possibly return

   *
   * @param string the string to test and possibly return
   * @return {@code string} if it is not null; {@code ""} otherwise
   */
  static String nullToEmpty(@Nullable String string) {
    return (string == null) ? "" : string;
  }

  /**
   * Returns the string if it is not empty, or a null string otherwise.
   *
   * @param string the string to test and possibly return