public async Task TestExchangeEURtoCOP(decimal value, string fromCurrency, string targetCurrency) { string url = @"http://data.fixer.io/api/latest?access_key=d0def2e2f997f931537d524b82434b2d&symbols=EUR,USD,COP"; ExchangeManager exchange = new ExchangeManager(url); decimal result = await exchange.ExchangeCurrencies(value, fromCurrency, targetCurrency); Assert.GreaterOrEqual(result, 0); }