FlowScope childAB = childA.createChildFlowScope();
childAB.inferSlotType("localB", STRING_TYPE);
FlowScope childABC = childAB.createChildFlowScope();
childABC.inferSlotType("localA", BOOLEAN_TYPE);
assertNull(childABC.findUniqueRefinedSlot(childABC));
assertTypeEquals(BOOLEAN_TYPE,
childABC.findUniqueRefinedSlot(childAB).getType());
assertNull(childABC.findUniqueRefinedSlot(childA));