public async Task <string> GetAccessTokenAsync(string appId, string appSecret)
{
if (string.IsNullOrWhiteSpace(appId))
{
throw new ArgumentNullException(nameof(appId));
}
if (string.IsNullOrWhiteSpace(appSecret))
{
throw new ArgumentNullException(nameof(appSecret));
}
using (var client = _httpClientFactory())
{
var uri = new Uri($"https://graph.facebook.com/oauth/access_token?client_id={appId}&client_secret={appSecret}&grant_type=client_credentials");
var response = await client.GetAsync(uri);
if (!response.IsSuccessStatusCode)
{
throw new FacebookApiException("Http client response was not successful.");
}
var content = await response.Content.ReadAsStringAsync();
if (string.IsNullOrWhiteSpace(content))
{
throw new FacebookApiException("Http client response was empty.");
}
var tokenObject = _jsonParser.ParseJsonResponse <FacebookAccessToken>(content);
if (tokenObject == null)
{
throw new FacebookApiException("Token parsing failed.");
}
return(tokenObject.AccessToken);
}
}
public void GetAccessToken_ShouldThrowFacebookApiException_WhenClientReponseParsingReturnsNull()
{
// Arrange
_httpMockHandler.When("*")
.Respond(HttpStatusCode.OK, "application/json", "content");
_jsonParser.ParseJsonResponse <FacebookAccessToken>(Arg.Any <string>())
.Returns(null as FacebookAccessToken);
var wrapper = new FacebookCommentsApiWrapper(_httpClientFactory, _jsonParser);
// Act
Func <Task> action = async() => await wrapper.GetAccessTokenAsync("appId", "appSecret");
// Assert
action.ShouldThrow <FacebookApiException>()
.And.Message.Should().Be("Token parsing failed.");
}