@Test
  public void testMalformedLocators() {
    Properties props = new Properties();

    // Totally bogus locator
    props.put(LOCATORS, "14lasfk^5234");
    assertThatThrownBy(() -> createSystem(props)).isInstanceOf(IllegalArgumentException.class);

    // missing port
    props.put(LOCATORS, "localhost[");
    assertThatThrownBy(() -> createSystem(props)).isInstanceOf(IllegalArgumentException.class);

    // Missing ]
    props.put(LOCATORS, "localhost[234ty");
    assertThatThrownBy(() -> createSystem(props)).isInstanceOf(IllegalArgumentException.class);

    // Malformed port
    props.put(LOCATORS, "localhost[234ty]");
    assertThatThrownBy(() -> createSystem(props)).isInstanceOf(IllegalArgumentException.class);

    // Malformed port in second locator
    props.put(LOCATORS, "localhost[12345],localhost[sdf3");
    assertThatThrownBy(() -> createSystem(props)).isInstanceOf(IllegalArgumentException.class);
  }
Tests that the default values of properties are what we expect
geode-core/src/integrationTest/java/org/apache/geode/distributed/internal/InternalDistributedSystemIntegrationTest.java