1. Code Coverage Revised
EclEmma
on JaCoCo
Evgeny Mandrikov

2. Code quality
1 of 7 deadly sins of developer
Insufficient code coverage by tests
http://sonarsource.com

3. Untested Code is the
Dark Matter of Software
Apparently because it
makes up 90% of the
software universe
Robert (Uncle Bob) Martin
August 2006

4. Correctness
Test App
Completeness

7. Requirements
A Library
Tested
Framework
Agnostic Scalable
Freaking Fast
Freaking Easy

8. Code Coverage
Runtime profiling Instrumentation
Source Bytecode
Offline On-The-Fly
Replace Inject Class Loader Java Agent

9. Java Byte Code
Instrumentation
ALOAD probearray
ICONST probeid
ICONST_1
BASTORE

10. Java Agent
$ java -javaagent:jacocoagent.jar killerApp
*.exec

11. Comparison
Emma Cobertura Clover JaCoCo
License CPL GPL Commercial EPL
Latest release 13/06/2005 03/03/2010 25/04/2012 19/04/2012
Type offline offline offline online
bytecode bytecode source code bytecode
Java 1.2 — 1.6 1.3 — 1.6 1.4 — 1.7 1.5 — 1.7
Line hits partial yes yes partial
Branch no yes yes yes
coverage

12. Comparison

13. Integrations
Ant Eclipse
Maven Sonar
IntelliJ IDEA
Aquillian
GUIDancer
SBT

15. Metrics
Types
Methods
Lines
Instructions
Branches
Complexity

16. Plug-in Testing
No more
Workspace Rebuilds!

17. Intermediate Dumps
Incremental Code
Coverage

18. Showcases
Fight Dark Matter
In Your Software!

19. Future
Determine relationship code - test
Even faster with JSR 292 (Java 7)
Filters
Inject into a running JVM (Java 6)

20. Contribute
http://jacoco.org

21. ?