Software Designers often have to face a common decision factor, that whether they need to design automated test (unit test, integration test etc) infrastructure for data access layer code, specially when the data access layer codes are written using code generator tool. Basically the straight forward answer as ‘Yes’ or ‘No’ in this regard depends of several situations/ factors such the size and budget of the project etc. Here are my 5 top reasons to write automated test (unit test, integration test etc) for generated data access layer code.

1. When the code generation template/logic itself contains bug

While using the code generators, it’s possible that the underlying code/logic of the code generators may contain bug! Having the automated test for the generated data access layer code greatly helps of indentify the ‘generated’ bugs!

2. When the code is not re-generated after to change of underlying database object

Well I swear my generated code engine is perfect (i.e. no bug on my generator engine/template logic)! Cool. I have generated the code perfectly. However I have changed the underlying database, but really forgot to re-generate the code using the code generator! Well that could be possible and can be detected if we have corresponding automated tests!

3. When the re-generated code is not perfect for the new changes of underlying database object

Well I swear my code has been re-generated after I have changed by database. Cool. But the initial version of generated code may work perfectly with the initial version of database objects. However, new bugs can be found/introduced in the generated code for the new changes of underlying database objects, which results updating the code generation logic. So, still you need automated tests for your data access layer code!

4. When custom code is added in the generated code

Sometimes custom code needs to be placed on the generated code. In those cases automated tests really helps a lot of indentify the bugs possibly placed in custom code in data access layer and/or in database stored procedure, function etc.

5. To check the perfect integration with database objects

Even the codes are generated/written for data access layer perfectly, but it’s still possible of failing the code running properly while the data access layer code and database objects are integrated. For instance using wrong connection string that points to wrong version of database etc. Having a well designed automated testing infrastructure really helps us in this regard!