@Test
    public void assertBudgetItemsMissingExceptionThrownWhenTotalCoreBudgetListIsNull() throws Exception {

        try {
            budgetCalculation.processBudgetItemsCalculation(annualBudget, breakdown);
            fail("CoreBudgetItemList is null.");
        } catch(BudgetItemsMissingException e) {
            assertEquals("BudgetItemsMissingException error message is correct.", "BudgetItemList is null.", e.getMessage());
        }



    }