         expectEqual(Decimal(68040), Decimal(386).advanced(by: Decimal(67654)))
         expectEqual(Decimal(1.234), abs(Decimal(1.234)))
         expectEqual(Decimal(1.234), abs(Decimal(-1.234)))
-        expectTrue(Decimal.nan.magnitude.isNaN)
+        if #available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *) {
+            expectTrue(Decimal.nan.magnitude.isNaN)
+        }
         var a = Decimal(1234)
         var r = a
         expectEqual(.noError, NSDecimalMultiplyByPowerOf10(&r, &a, 1, .plain))

                expectEqual(.noError, NSDecimalPower(&result, &actual, j, .plain))
                let expected = Decimal(pow(Double(i), Double(j)))
                expectEqual(expected, result, "\(result) == \(i)^\(j)")
                expectEqual(expected, pow(actual, j))
            }
        }
    }

        expectFalse(zero.isNaN)
        expectFalse(zero.isSignaling)

        if #available(macOS 10.15, iOS 13, tvOS 13, watchOS 6, *) {
            let d1 = Decimal(1234567890123456789 as UInt64)
            expectEqual(d1._exponent, 0)
            expectEqual(d1._length, 4)
        }
    }
    func test_Constants() {
        expectEqual(8, NSDecimalMaxSize)
