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A New TDD Strategy using Caraya

At the 2016 CLA Summit, I watched Philippe's presentation on Caraya and it made me think about a deeper question - could Caraya help me do Test Driven Development (TDD) in LabVIEW?  I started exploring this idea and quickly was able to create a strategy that I think lowers the barrier for TDD enough for me to give it a shot again.

The highest level view of this approach is:

Create the test in the VI that is being developed instead of as a separate test VI.

In its simplest form, here is an example of the test template:

TDD VI Template.png

The benefits of this approach are: simplicity and usability without a run-time performance penalty.  The only downside I can see initially is that the test code itself can make it harder to read the actual functionality being tested - but I think this is not an unacceptable trade-off.  If the scaffolding gets too complex, etc, the scaffolding can be converted to a separate test VI and you will fall back to what we currently are doing in the LabVIEW community - but with the benefit that we at least *started* with a test first approach.

I've documented the entire project template (which includes dynamic setting of the "TDD" conditional symbol, and running tests as a pre-build step of the executable build).

After getting some initial feedback from CLAs including: Russel Blake, Fabiola De la Cueva (and others that I can't think of right now) and demonstrating the idea to a few more CLAs I felt pretty excited so I cleaned it up even more.  I've created a VI Package that creates a project template for doing TDD.  A quick disclaimer - I haven't yet actually used this template for TDD LabVIEW development yet, but I intend to start trying right away.  I want to know if anyone else has feedback on this idea so I created the tool on GitHub so others can contribute easily.  The Github repo for all source code to create the package is here:


I hope others are as excited as I am!  Let me know your thoughts.

Message 1 of 4

Hi Omar,

This is an interesting idea but for me seems to have some serious scalability issues when I'm using TDD:

  1. Autodetect would be really important. I have around 60-100 test cases in many of my projects.
  2. I would often have multiple test cases for the same VI. If I start with this method (that doesn't easily support this) this is going to cause friction and I will probably find shortcuts and not test properly.

This is interesting to see though and I'm excited to see some potential templates based on Caraya. It seems to handle the test cases well but the workflow is a bit more open/you have to think for yourself (which can be a good thing!)



James Mc
CLA and cRIO Fanatic
My writings on LabVIEW Development are at devs.wiresmithtech.com
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Message 2 of 4

Hi James,

Regarding your points:

1 - Autodetect - I'm assuming you mean like the comment in the build hook example ("Future version should support dynamic discovery of all callers of "Caraya.Define Test" method"?  I don't think that is too difficult to do but it wasn't my first priority for creating the initial project template.

2 - I agree that often you'll need multiple test cases - in which case here's the crazy part - you can just invert the code to go back to what you previously did - the inversion process is this:

Rename your VI to "Test ABCD" (or whatever you want - Caraya doesn't care) and then create a subVI of the code under test as ABCD.vi.  Effectively you fall back into the traditional developement path - but the potential benefit is that you started from a test first position.

The main obstacle I found so far is that in most of my coding I'm working on adding functionality to something that already exists so I almost never start from New VI and instead start most of my VIs from "Create SubVI from selection" - so I'm planning to create a scripting plugin (TBD) that can help with that part.

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Message 3 of 4


I like really this idea.  I find it similar to a python library I like a great deal, doctest https://docs.python.org/2.7/library/doctest.html.  As you can see that the tests serve a triple duty of testing, documenting, and providing use examples in one place.  Granted the set of test vectors could get unwieldy, but I think that the generat benefits outweigh that.

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Message 4 of 4