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Earlier today, Dorothy Graham presented a webinar on her thoughts about test coverage. For me, listening to this webinar was a trip down memory lane – I immediately thought of the ISTQB Foundation exam I sat in 2012 and the multi-choice questions I had to prepare for when it came to the different types of coverage (But I really enjoyed hearing Dorothy’s analogies on coverage (I find analogies are a great way to explain things). This post is not a summary of webinar, but just some of my highlights.


The travel analogy

Dorothy started off with an analogy using Scratchie maps – those ones where you (typically) scratch off the countries you have visited. She questioned “But what do I scratch off? cities? states? countries?” Initially she scratched off 74 cities in the map, but we couldn’t really see them.

She then proceeded to scratch off states then countries. But she commented that it wasn’t really representative of how much of these places she’s actually experienced – it was “rather shallow coverage”. (For example: scratching off all of Brazil when you have only been to Rio de Janeiro)


What is coverage?


“An Objective measurement of some aspect of thoroughness”

In my opinion, people should really pay attention to the “some aspect” part – that is, the person reporting the coverage has specifically chosen this type of coverage. It’s always good to check how they have defined coverage and why they chose to measure the test coverage in that specific way.

She then later explored different ways of measuring coverage: menu options, errors, lines of code etc. And then explained when you see “85% coverage or 100% coverage” that it’s one type of coverage. (Feel free to watch the webinar online if you’d like to learn more about the different types of coverage)

The butter and strawberry jam analogy

Butter (to explain width of coverage)
When you spread butter on toast it tends to go on evenly and all over the slice of bread. 

Strawberry Jam (to explain depth of coverage)
When you spread strawberry jam on jam, it doesn’t go on the toast evenly, some parts of the bread are more “well covered” than others.


My biggest takeaways:

My biggest takeaways from this webinars were the travel analogy and the butter and strawberry jam analogy. To be honest, I feel like I already have a solid understanding of the different types of coverage, but getting some interesting new ideas on how to explain coverage to clients was definitely beneficial. 
 

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