Improving Spreadsheet Test Practices

Improving Spreadsheet Test Practices

Felienne Hermans (@felienne)

Improving Spreadsheet Test Practices

Felienne Hermans (@felienne)

In this slidedeck I’ll present my research on applying test practices to spreadsheets.

Improving Spreadsheet Test Practices

Felienne Hermans (@felienne)

In this slidedeck I’ll present my research on applying test practices to spreadsheets.

First of all? Why would you want or need to test a spreadsheet? It’s just that simple thing that you use to keep track of your morgage and that’s not rocket science.

My vision on this is that spreadsheets are actually software.

My vision on this is that spreadsheets are actually software.

And with that, I do not mean that a spreadsheet program is a piece of software.

Rather, I claim that the act of making a spreadsheet is similar to building a piece of code.

My vision on this is that spreadsheets are actually software.

And with that, I do not mean that a spreadsheet program is a piece of software.

Rather, I claim that the act of making a spreadsheet is similar to building a piece of code.

There are three reasons for this:

1) Structuring data is a programming act

1) Structuring data is a programming act

When spreadsheet users think about what data to put where,

for instance in what table or worksheet,

they are actually modeling their domain, just as programmers do when they decide what methods to put in what class.

2) Formulas are Turing complete

2) Formulas are Turing complete

I built a Turing machinewith spreadsheet formulas only to prove my point:

http://www.felienne.com/?p=2974

3) Spreadsheet suffer from ‘software’

problems

3) Spreadsheet suffer from ‘software’

problems

3) Spreadsheet suffer from ‘software’

problems

3) Spreadsheet suffer from ‘software’

problems

Knowing that spreadsheets are software, does that help us?

In my dissertation, I researched spreadsheet smells and

refactoring

Now I wonder: should we also test them?

Testing seems to work for software

But how do we get spreadsheet users to test?

We were looking the wrong way!

We were looking the wrong way!Spreadsheet users are great

testers

These types of tests are very common

8.8%of spreadsheets contain such tests

8.8%of spreadsheets contain such tests And spreadsheet

users are quite

good at testing

too!

35%average ‘coverage’ of the testformulas

What can we do to improve this?

We built Expector, an Excel pluginthat detects existing test formulas

This view helps users understand the

‘testedness’ of their sheets

Improving Spreadsheet Test Practices

Felienne Hermans (@felienne)