OWIN, OAuth - Bearer tokens: Authentication and Authorization for unit tests

It is a fact that nowadays, SPA applications are used in almost all new web project. In general behind a SPA application we have multiple REST endpoints that are used to get data, execute different actions and many more.
Token base authentication is worldwide use when we need to secure a REST endpoint and offer a mechanism for authentication and authorization.

In general when we create a SPA application using AngularJS we will use token based authentication. This mean that we will have an endpoint called ‘token’ (or other path) where users can send their username and password and receive a token that can be used to access different resources. Once we have the token, we will set the bearer token value of the authorization heather.

Beside this we need to be able to write unit tests or integration tests that hit our REST services and validate their functionality. For this purpose we need to have a code that simulates the authentication step and inject in the REST request the bearer token.
Below you can find the C# code that can be used for this purpose. In constructor, the REST endpoint is called and access token is created. Once this step is done, the "SetAuthorizationToken" can be called to set the authorization token on http client.

public class AuthorizationHelper
{                        
    private string accessToken;

    public AuthorizationHelper(string serverUrl, string username, string password)
    {
        ResolveBearerToken(username, password, serverUrl);
    }

    private void ResolveBearerToken(string username, string password, string serverUrl)
    {
        using (HttpClient httpClient = new HttpClient())
        {
            httpClient.BaseAddress = new Uri(serverUrl);
            SetHeatherInformation(httpClient);

            // Have to
            StringContent content = new StringContent(
                                            string.Format("grant_type=password&username={0}&password={1}", username, password),
                                            Encoding.UTF8, 
                                            "application/x-www-form-urlencoded");
            Task<HttpResponseMessage> responseTask = httpClient.PostAsync("token", content);
            responseTask.Wait();
            HttpResponseMessage response = responseTask.Result;

            if (response.StatusCode != HttpStatusCode.OK)
            {
                throw new Exception(string.Format("Auth failed for user '{0}' with status code '{1}'", username,
                    response.StatusCode));
            }

            Task<object> readResponseTask = response.Content.ReadAsAsync<object>();
            readResponseTask.Wait();
            dynamic responseContent = readResponseTask.Result;
            accessToken = responseContent.access_token;

            if (accessToken == null)
            {
                throw new Exception("Auth token is null.");
            }
        }
    }

    private static void SetHeatherInformation(HttpClient httpClient)
    {
        httpClient.DefaultRequestHeaders.UserAgent.ParseAdd(@"Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/40.0.2214.91 Safari/537.36");
        httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(@"text/plain"));
        httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue(@"*/*"));            
        httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/x-www-form-urlencoded"));
    }

    public void SetAuthorizationToken(HttpClient httpClient)
    {
        httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);
    }
}

Enjoy!