@Test
  public void fromJsonWithNullStringThrowsNullPointerException() {
    // given: null string
    String nullString = null;

    // when: passed to fromJson
    Throwable thrown = catchThrowable(() -> fromJson(nullString));

    // then: throws NullPointerException
    assertThat(thrown).isInstanceOf(NullPointerException.class).hasNoCause();
  }
Unit tests for {@link LocatorLauncher.LocatorState}.
geode-core/src/test/java/org/apache/geode/distributed/LocatorStateTest.java