1. Jester – The JUnit Test Tester
“Why just think your tests are good when you can know for sure? Sometimes Jester tells me my tests are airtight, but sometimes the changes it finds come as a bolt out of the blue. Highly recommended.” Kent Beck

2. What is Jester? tests Java code and JUnit tests
extends traditional Code Coverage
finds test-suite problems
finds untested statements
provides unique insights into the structure of a code base

3. How does Jester work? (1)
Knowing that a statement isn't executed at least
once by the test suite, proves that it isn't being
tested.
If a line of code is executed, it doesn't necessarily
follow that it's tested.

4. How does Jester work? (2)
Unlike a traditional code coverage tool, Jester doesn't watch which lines of code have been executed. Instead Jester changes the source code, recompiles it, and runs the test suite to see if anything breaks.
For instance, it will change a 1 to a 2, or change an if (x > y) to if (false). If the test suite isn't paying close enough attention to notice the change, then a test is missing.

5. How to install Jester
download Jester from
J2SE (>=1.4) and JUnit must already be installed
add Jester to the classpath
run a simple example with 'test.bat‘ (the directory
containing 'test.bat' must also be on the classpath.

6. How to run Jester (1)

7. How to run Jester (2)

8. Jester and XML

9. Jester‘s Licence Model
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, provided that the above copyright notice(s) and this permission notice appear in all copies of the Software and that both the above copyright notice(s) and this permission notice appear in supporting documentation.