public void total() { List<CurrencyAmountArray> arrays = ImmutableList.of( CurrencyAmountArray.of(USD, DoubleArray.of(10, 20, 30)), CurrencyAmountArray.of(USD, DoubleArray.of(5, 6, 7)), CurrencyAmountArray.of(EUR, DoubleArray.of(2, 4, 6)), CurrencyAmountArray.of(GBP, DoubleArray.of(11, 12, 13)), CurrencyAmountArray.of(GBP, DoubleArray.of(1, 2, 3))); Map<Currency, DoubleArray> expectedMap = ImmutableMap.of( USD, DoubleArray.of(15, 26, 37), EUR, DoubleArray.of(2, 4, 6), GBP, DoubleArray.of(12, 14, 16)); MultiCurrencyAmountArray expected = MultiCurrencyAmountArray.of(expectedMap); assertThat(MultiCurrencyAmountArray.total(arrays)).isEqualTo(expected); }