public Timestamp updateToRunning(String partitionToken) {
    final TransactionResult<Void> transactionResult =
        runInTransaction(
            transaction -> transaction.updateToRunning(partitionToken), "updateToRunning");
    return transactionResult.getCommitTimestamp();
  }
@Test
  public void testInTransactionContextCannotUpdateToRunning() {
    ArgumentCaptor<ImmutableList<Mutation>> mutations =
        ArgumentCaptor.forClass(ImmutableList.class);
    ResultSet resultSet = mock(ResultSet.class);
    when(transaction.executeQuery(any(), anyObject())).thenReturn(resultSet);
    when(resultSet.next()).thenReturn(false);

    doNothing().when(transaction).buffer(mutations.capture());
    assertNull(inTransactionContext.updateToRunning(PARTITION_TOKEN));
    // assertEquals(0, mutations.getValue().size());
    verify(transaction, times(0)).buffer(mutations.capture());
  }