About me
- Developer / QA Specialist / Manager
- In Switzerland for the last eight years
- Currently working at UBS
Support
- I support Manchester United
Support
- And Southampton
Code Coverage
- Tells you how much of your code you have tested
- There are various coverage criteria
- "Testing never proves the absence of faults, it only shows their presence." Edsger Dijkstra
- Trying to cover more of the testing problem space
Code coverage metrics
- Subroutine Coverage
- Statement Coverage
- Branch Coverage
- Path Coverage
- Condition Coverage
- Documentation Coverage
Methodology
- Make sure your tests all pass
- Run your tests using your coverage tool
- Check your coverage reports
- Write additional tests for uncovered code
- Or remove the code
- Or rewrite it
When the tests have run
- Only the beginning
- Any serious drive for quality takes effort and resources
- Quality is not guaranteed, merely improved
- Don't rely on code coverage
Devel::Cover
- Code coverage tool for Perl
- Mostly designed cycling up the hill from Triemli to Uitikon
runops
- Perl compiles code to an optree
- runops function walks the optree and calls appropriate functions
- Devel::Cover replaces the runops function and does evil things
- Experimental code messes with the vtable to call different functions
Back to Reality
- At the end, Devel::Cover walks the optree again, mapping the ops back to reality and associating the coverage data
- Databases containing coverage data from different runs are merged
- Finally a report outputs the data in a pretty web page
- Or in any other format
Other Languages
- Translates from other coverage tools into Devel::Cover's database format
- Currently only gcov from gcc
- Works nicely for combined Perl and C projects
Future
- Implement Path Coverage
- Mutation Coverage
- Regular Expression Coverage
- Fully buzzword compliant AJAXy GUI