public void test_subtract_nullBoth() {
   assertEquals(MoneyUtils.subtract((BigMoney) null, (BigMoney) null), null);
 }
 public void test_subtract_null2() {
   assertSame(MoneyUtils.subtract(GBP_20, (BigMoney) null), GBP_20);
 }
 @Test(expectedExceptions = CurrencyMismatchException.class)
 public void test_subtract_differentCurrencies() {
   MoneyUtils.subtract(GBP_20, EUR_30);
 }
 public void test_subtract_null1() {
   assertEquals(MoneyUtils.subtract((BigMoney) null, GBP_30), GBP_M30);
 }
 // -----------------------------------------------------------------------
 // subtract(Money,Money)
 // -----------------------------------------------------------------------
 public void test_subtract() {
   assertEquals(MoneyUtils.subtract(GBP_20, GBP_30), GBP_M10);
 }