@Test
  public void fromJsonWithEmptyStringThrowsIllegalArgumentException() {
    // given: empty string
    String emptyString = "";

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

    assertThat(thrown).isInstanceOf(IllegalArgumentException.class)
        .hasCauseInstanceOf(NullPointerException.class);
    assertThat(thrown.getCause()).isInstanceOf(NullPointerException.class).hasNoCause();
  }
Unit tests for {@link ServerLauncher.ServerState}.
geode-core/src/test/java/org/apache/geode/distributed/ServerStateTest.java