visual studio - The problem with NUnit and app.config

Question

When i run a simple test on connection to DB check i receive an error in NUnit:

[Test]
public void TestConn()
{
    string  connectionString = ConfigurationManager.ConnectionStrings["FertigungRead"].ConnectionString;
    SqlConnection connection = new SqlConnection(connectionString);
    connection.Open();
    Assert.AreEqual(ConnectionState.Open, connection.State);
    connection.Close();
 }

System.NullReferenceException : Object reference not set to an instance of an object.

on line :

connectionString = ConfigurationManager.ConnectionStrings["FertigungRead"].ConnectionString;

Can i use ConfigurationManager in tests?

Answer 1

Yes, you can. You need to be sure that any configuration you are referencing in your tests actually exist in the app.config of the test project.

In other words, the project where your test is in, does not have a connection string "FertigungRead" defined in its app.config.

One way to do this is to add the app.config of the system under test to the test project as a link, this way any changes happen on both projects.