[Simpletest-support] Testing philosophy?

[Jason S. <jsw...@ya...>]

This project that I am working on is a DataCache.  I wanted to be able to
implement it either using the file system or using a database, so I decided to
make a DAO to support either of these options, and have a DataCache class that
decides which of the DAOs to use.

When constructing a test for this kind of a system, I assume it is fine to
write unit test cases for each of the DAOs, however when it comes to the
DataCache class itself, is it better to test the DAOs first, then the DataCache
as written, or is it better to mock the DAOs and test the outer class by
itself?

Any guidlines or rules of thumb that you use in these cases?

Thanks.

Jason

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