抛出HttpException时，如何编写单元测试来检查http状态代码？

Question

I am coding an API client, which should throw a System.Web.HttpException with the appropriate HTTP status code when the request is not successful. I know that I can test that HttpException is thrown by using the [ExpectedException(typeof(HttpException))] attribute, but this won't tell me that the status code was correct. How can I assert that the status code is correct?

Here is my client:

public static async Task<HttpResponseMessage> SubmitRequest(string endPoint, string apiKey)
{
    ServerResponse serverMessage = new ServerResponse();
    var credentials = Convert.ToBase64String(Encoding.ASCII.GetBytes(String.Format( "{0}:", apiKey)));

    using (var client = new HttpClient())
    {
        client.BaseAddress = new Uri("https://localhost/api/v1/");
        client.DefaultRequestHeaders.Accept.Clear();
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue( "Basic", credentials );

        // HTTP GET
        HttpResponseMessage response = await client.GetAsync(endPoint);
        // if response status code is in the range 200-299
        if (response.IsSuccessStatusCode)
        {
            return response;
        }

        // request was not successful
        if (response.StatusCode == HttpStatusCode.Unauthorized)
        {
            throw new HttpException(401, "Not authorized.");
        }
    }
}

Answer 1

You can test the HTTP status code by using a try-catch statement in your unit test. It seems that you can't mix the try-catch approach with an ExpectedException() attribute though. If you do, you will get a message like this:

Test method did not throw an exception. An exception was expected by attribute Microsoft.VisualStudio.TestTools.UnitTesting.ExpectedExceptionAttribute defined on the test method.

However, you can catch the HttpException in a regular unit test, and assert that the status code is correct in the catch block:

[TestMethod]
public async Task ApiClient_ThrowsHttpException401IfNotAuthorised()
{
    //arrange
    string apiKey = "";
    string endPoint = "payments";
    //act
    try
    {
        HttpResponseMessage response = await ApiClient.SubmitRequest(endPoint, apiKey);
    }
    //assert
    catch (HttpException ex)
    {
        // HttpException is expected
        Assert.AreEqual(401, (int)ex.GetHttpCode());
        Assert.AreEqual("Not authorized.", ex.Message);
    }
    catch (Exception)
    {
        // Any other exception should cause the test to fail
        Assert.Fail();
    }
}