单元测试。 关于独立测试

Question

Before downvote my question please listen :) I use unit test. And I know they must be independently from each other. Though how to test repository for book. First book must be created, then updated and then deleted. Three unit tests I have. Isn't it right to have dependency for these unit tests?

   [TestFixture]
    public class CompanyRepositoryTests
    {
        public void CreateCompany()
        {
           // This must be called 1
        }

        public void UpdateCompany()
        {
           // This must be called 2
        }

        public void DeleteCompany()
        {
            // This must be called 3
        }
    }

Answer 1

A thing about unit tests (as opposed to integration tests) is that they're only supposed to test a single method. So for instance, if you have a method that looks like this:

public void createCompany(Company c) {
  if (c == null) {
    throw new NullPointerException();
  }
  database.create(c);
}

A good test for it will only test two things:

1. If null is passed in, NullPointerException is thrown
2. If non- null is passed in, database.create() gets called

Whether database.create() actually does anything useful is a different question. One that has to do with unit-testing the database.

In your case, mock out the underlying storage as suggested, and write proper unit tests.

In integration tests on the other hand, having dependencies is clearly fine. Even if so, your tests should look like

• test 1: fresh database: create a company, make sure it's there.
• test 2: fresh database: create a company, delete it, make sure it's gone.
• test 3: fresh database: create a company, modify it, make sure it worked.

every test should be starting from scratch.

Answer 2

In this exercise, you will learn how to test CRUD actions that modify the database. One of the premises to take into account is that tests don't necessarily run in a specific order. Another one is that every test could be executed as many times as needed. So your tests should not depend on previous tests executions. For instance, if your test is going to delete a record in the database, the setup of the test should provide the record to be deleted. This way, the test could be executed repeatedly.

Good tutorial about unit tests

Answer 3

you could mock the dependencies.

hava a look at http://code.google.com/p/mockito/