创建数据库连接错误NUnit C＃

Question

I'm developing an application in C# and I need to write unit tests for it. One of the test requires the ability to handle exception when stuff like connection to database is lost/erroneous. What's the best practice to create such kind of error? For example, changing connectionString at run time, etc.

Answer 1

I would recommend using a mocking framework to set-up your testable class (for example, a Repository with an Interface) to throw an error. For example, using Moq, you could do this in your unit test:

var mockRepo = new Mock<IRepository>();

mockRepo.Setup(x => x.GetCustomer(1))
        .Throws(new Exception("unable to connect to database"));

You can then Assert that the exception was thrown in your test.

Assert.Throws<Exception>(() => mockRepo.Object.GetCustomer(1));