1. Testing and Refactoring
Spreadsheets
Felienne Hermans
Delft University of Technology

2. Felienne Hermans
Delft University of Technology
Testing and Refactoring
Spreadsheets

3. 95% of all U.S. firms use spreadsheets for
financial reporting

4. 90% of all analysts in industry perform
calculations in spreadsheets

5. Importance can grow over time

6. And, spreadsheet exist
‘under the radar’

7. Only 33% of spreadsheets has
a manual

8. Complex spreadsheets without
documentation can lead to serious errors

9. The European Spreadsheet Risk Interest
Group (Eusprig.org) collects horror stories

20. Why?

21. No documentation, errors, long life
It looks like…?

22. No documentation, errors, long life
It looks like software!

23. For software, tools have been created to
help programmers write good code

27. We bring quality tools to spreadsheets

28. BumbleBee:
A tool for spreadsheet improvement

37. But, not all transformations have to be
behavior preserving

49. You can download BumbleBee from
my website (felienne.com)

50. The transformations are entirely
programmable, with a small language

51. Expector:
A tool for spreadsheet testing

53. These test formulas can be exploited

54. Our tool Expector can find test formulas

60. Expector helps users to understand
robustness of their spreadsheets

66. More info? Over drinks, send me an
email (f.f.j.hermans@tudelft.nl) or visit
felienne.com