public async Task ReturnsValidResponseWhenPassedValidPair()
{
var client = new ExchangeRatesApiClient();
var data = await client.GetExchangeRate(new Currency("USD"), new Currency("EUR"));
Assert.IsNotNull(data);
}
public async Task ReturnsNullWhenPassedInvalidTargetCurrency()
{
var client = new ExchangeRatesApiClient();
var data = await client.GetExchangeRate(new Currency("XYZ"), new Currency("USD"));
Assert.IsNull(data);
}
/// <summary>
/// Should return exchange rates among the specified currencies that are defined by the source. But only those defined
/// by the source, do not return calculated exchange rates. E.g. if the source contains "EUR/USD" but not "USD/EUR",
/// do not return exchange rate "USD/EUR" with value calculated as 1 / "EUR/USD". If the source does not provide
/// some of the currencies, ignore them.
/// </summary>
public async Task <IEnumerable <ExchangeRate> > GetExchangeRates(IEnumerable <Currency> currencies)
{
var client = new ExchangeRatesApiClient();
var currencyPairs = new List <Tuple <Currency, Currency> >();
// get pairs
foreach (var baseCurrency in currencies)
{
var targets = currencies.Where(c => c.Code != baseCurrency.Code);
currencyPairs.AddRange(targets.Select(t => new Tuple <Currency, Currency>(baseCurrency, t)));
}
// obtain rates without excessive thread blocking
var results = await Task.WhenAll(currencyPairs.Select(pair => client.GetExchangeRate(pair.Item1, pair.Item2)));
return(results.Where(rate => rate != null).ToList());
}
