@Test 
public void testTwoJoinsToOneParent() {

    builder.joinTables("co2", "schema", "customer", "schema", "order");
    builder.joinColumns("co2", "schema", "customer", "customer_id", "schema", "order", "customer_id");
    builder.groupingIsComplete();
    Collection<AISValidationFailure> failures = builder.akibanInformationSchema().validate(validations).failures();
    Assert.assertEquals(1, failures.size());
    AISValidationFailure fail = failures.iterator().next();
    Assert.assertEquals(ErrorCode.JOIN_TO_MULTIPLE_PARENTS, fail.errorCode());
}