//-------------------------------------------------------------------------
        public virtual void test_convert()
        {
            FxRate test = FxRate.of(GBP, USD, 1.25d);

            assertEquals(test.convert(100, GBP, USD), 125d);
            assertEquals(test.convert(100, USD, GBP), 100d / 1.25d);
            assertThrowsIllegalArg(() => test.convert(100, GBP, AUD));
        }