Unit test for connection / C#

Question

Writing test for my application. Would like to test connection with exeption handling, for now I have created method which works and looks like :

        [Test]
        public void TestCreateConnection()
        {
            Connection testConnection = new Connection();
            connection.CreateConnection(correctURL, IDName + connection.ApiKey, connection.ContentType, connection.MediaType, connection.Get, false, "name");
            testConnection.CreateConnection(correctURL, IDName + connection.ApiKey, connection.ContentType, connection.MediaType, connection.Get, false, "name");
        }

In the finall version working on smth which will catch exception - WebExeption. Already have it in try / catch block inside my method which is about to create connection, it works ofc. But need it in my test as well. I was thinking it should looks like :

[Test]
        [ExpectedException(typeof(WebException))]
        public void TestCreateConnection()
        {
            Connection testConnection = new Connection();
            connection.CreateConnection(correctURL, IDName + connection.ApiKey, connection.ContentType, connection.MediaType, connection.Get, false, "name");

            testCconnection.CreateConnection(correctURL, IDName + connection.ApiKey, connection.ContentType, connection.MediaType, connection.Get, false, "name");
            Assert.Catch<WebException>(() => connection.CreateConnection("test", IDName + connection.ApiKey, connection.ContentType, connection.MediaType, connection.Get, false, "name"););
        }

Like we can see i changed first arg of the method which is URL address, it will couse the web exeption. How can i write it in correct way ?

Answer 1

I don't think there is anything wrong in your approach of testing the exception. I do suggest, however, that you split your test into two tests - one for the case where you get a valid connection, and one for the case where you get a bad connection.

    [Test]
    public void WhenCorrectUrlIsPassedConnectionCreatedSuccessfully()
    {
        Connection testConnection = new Connection();
        connection.CreateConnection(correctURL, IDName + connection.ApiKey, connection.ContentType, connection.MediaType, connection.Get, false, "name");
    }

    [Test]
    [ExpectedException(typeof(WebException))]
    public void WhenIncorrectUrlIsPassedThenWebExceptionIsThrown()
    {
        Connection connection = new Connection();
        Assert.Catch<WebException>(() => connection.CreateConnection("test", IDName + connection.ApiKey, connection.ContentType, connection.MediaType, connection.Get, false, "name"););
    }

This is without knowing the exact details of how you implemented the test connection. If you have some internal component in charge of creating the connection, and your code is a wrapper around it, then you should consider passing the internal component in as an Interface and mocking its behavior.