Conditional Processing

Bill Fellows shows options for handling date-based conditional processing:

Do you see the problem? Really, there are two but the one I’m focused on is the use of GETDATE to determine which branch of logic is executed. Today is Monday and I need to test the logic that runs on Friday. Yes, I can run these steps in isolation and given that I’m not updating the logic that fiddles with the branches, my change shouldn’t have an adverse effect but by golly, that sucks from an testing perspective. It’s also really hard to develop unit tests when your input data is server date. What are you going to do, allocate 5 to 7 days for testing or change the server clock. I believe the answer is No and OH HELL NAH!

This isn’t just an SSIS thing, either. I’ve seen the above logic in TSQL as well. If you pin your logic to getdate/current_timestamp calls, then your testing is going to be painful.

I liken this to solving dependency injection problems in general:  make the caller define the date or date part.  That way, your test callers can define other dates and the “smarts” around which branch to take move up to a more swappable layer.

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