Should I unit-test my grid rendering logic?

Question

Hello,

I have a simple project, mostly consisting of back-end service code. I have this fully unit-tested, including my DAL layer...

Now I have to write the front-end. I re-use what business objects I can in my front-end, and at one point I have a grid that renders some output. I have my DAL object with some function called DisplayRecords(id) which displays the records for a given ID...

All of this DAL objects are unit tested. But is it worth it to write a unit test for the DisplayRecords() function? This function is calling a stored proc, which is doing some joins. This means that my unit-test would have to set-up multiple tables, one with 15 columns, and its return value is a DataSet (this is the only function in my DAL that returns a datset - because it wasnt worth it to create an object just for this one grid)...

Is stuff like this even worth testing? What about front-end logic in general - do people tend to skip unit tests for the ASP.NET front-end, similar to how people 'skip' the logic for private functions? I know the latter is a bit different - testing behavior vs implementation and all... but, am just curious what the general rule-of-thumb is?

Thanks very much

Answer 1

I tend to make quick Selenium tests and just sit and watch the app do its thing - that's a fast validation method which avoids all the manual clicking.

Fully automated UI testing is tedious and should IMO only be done in more mature apps where the UI won't change much. Regarding the 'in-between' code, I would test it if it is reused and/or complicated/ introducing new logic, but if its just more or less a new sequence of DAL method calls and specific to a single view I would skip it.

Answer 2

There are a few things that weigh into whether you should write tests:

• It's all about confidence. You build tests so that you have confidence to make changes. Can you confidently make changes without tests?

• How important is this code to the consumers of the application? If this is critical and central to everything, test it.

• How embarrassing is it if you have regressions? On my last project, my goal was no regressions-- I didn't want the client to have to report the same bug twice. So every important bug got a test to reproduce it before it was fixed.

• How hard is it to write the test? There are many tools that can help ease the pain:

  1. Selenium is well understood and straightforward to set up. Can be a little expensive to maintain a large test suite in selenium. You'll need the fixture data for this to work.

  2. Use a mock to stub out your DAL call, assuming its tested elsewhere. That way you can save time creating all the fixture data. This is a common pattern in testing Java/Spring controllers.

  3. Break the code down in other ways simply so that it can be tested. For example, extract out the code that formats a specific grid cell, and write unit tests around that, independent of the view code or real data.