How to safely unit-test write operations in Symfony 2?

Running any kind of tests on a production server is generally a bad idea (unless it's just the production hardware that hasn't been commisioned yet).

A Unit Test does not hit the database (or any other external system). So, in order to create a unit test you need to remove the dependency on the database.

What you are calling a 'unit test' is probably an integration test. Any test that utilises an external system (such as a database, file system etc.) is an integration test.

Two common solutions to your problem are:

1. At the start of your test, restore a database backup containingknown data to a separate test database, then perform your testsagainst it.

2. Using a 'fixed' known test database, at the start of each test starta transaction, perform the test and then rollback the transaction toleave the database in the same known state.

(No. 1 is often preferable, as the database in (2) can become 'polluted').

I agree with Mitch. I would add that you should decide whether you want to do an integration test or a unit test (or both, but not in the same test). If, in fact, you do want to do a unit test, realize:

1. Your code has a "dependency" on an external database.
2. When unit testing you'll have to find a way to "fake" the database. You want to test a "unit" which means a single thing, not two or more things (i.e. your CRUD code AND your connection to a database AND the database itself).
3. Typically you'll need to refactor your code using something like dependency injection so that when unit testing you can fake things that your code depends on.

Unit testing isn't just testing your code. That's actually the easy part. The harder part is making your code testable.

I recommend going to http://artofunittesting.com/ and watching the free videos on the right side under the heading "Unit Testing Videos". Forget the fact that he's working in .NET as it's the principles that are important.

Then watch the GoogleTechTalks by Misko Hevery where he explains why you want to do dependency injection.

Design Tech Talk Series Presents: OO Design for Testability

The Clean Code Talks -- Unit Testing

(He has more too. There is a series of six GoogleTechTalks.)

I had a similar problem today and I think I've found a good solution.

• Make a copy of your database (creating a new empty database works as well).
• Edit your config_test.yml to change the database name.

A sample of my test configuration (might be different depending if you have multiple db-s etc)

doctrine:    dbal:        dbname: test_db

• Update your database to reflect the entities in your application by calling php app/console doctrine:schema:update --force --env=test (required, if you just created a new db as well as every time you change your application model).

Your application should now use the test database during unit tests. NB! Be sure to make a backup of your database before messing around with the live database.

However, as clearly mentioned before, these are not Unit Tests anymore and instead an integration tests.