@Test
  public void testNetworkPartitionDetectedWithNullView() throws Exception {
    initMocks(true);
    prepareAndInstallView(mockMembers[0], createMemberList(mockMembers[0], gmsJoinLeaveMemberId));

    NetworkPartitionMessage message = new NetworkPartitionMessage();
    message.setSender(gmsJoinLeaveMemberId);


    // this creates a NPE that must be handled appropriately
    gmsJoinLeave.currentView = null;
    assertThatNoException().isThrownBy(() -> gmsJoinLeave.processNetworkPartitionMessage(message));

  }
Given a view with [A, B, C, D] where C is coordinator, a failed availability check on A
and a pending join request from E show that B becomes coordinator when C sends it a
Leave request and that E is allowed into the system and retains its view ID.
See GEODE-6570
geode-membership/src/integrationTest/java/org/apache/geode/distributed/internal/membership/gms/membership/GMSJoinLeaveJUnitTest.java