public async Task TestDoExchangeAsync()
{
// Arrange
Cache cacheThatWasSet = null;
mockCacheService.Setup(_ => _.SetCache(It.IsAny <Cache>()))
.Callback <Cache>((cache) => cacheThatWasSet = cache);
SetupHttpClientForExchangePost();
SetupHttpClientFactory();
SetupHttpRequestService();
httpRequestService = new HttpRequestService(mockHttpClientFactory.Object,
mockCacheService.Object, trueLayerCredentialsOptions);
// Act
await httpRequestService.DoExchangeAsync(dummyCode);
// Assert
Assert.NotNull(cacheThatWasSet.ExchangeResponseDTO);
Assert.Equal(cacheThatWasSet.ExchangeResponseDTO.AccessToken, dummyAccessToken);
}