@NullMarked
@GwtCompatible
public class SplitterTest extends TestCase {

  private static final Splitter COMMA_SPLITTER = Splitter.on(',');

  @SuppressWarnings("nullness") // test of a bogus call
  public void testSplitNullString() {
    assertThrows(NullPointerException.class, () -> COMMA_SPLITTER.split(null));
  }

  public void testCharacterSimpleSplit() {
    String simple = "a,b,c";