Instructions to compile and run TestPasswordValidator.java:

1. Download junit-4.8.2.jar from http://github.com/KentBeck/junit/downloads to
the same directory where you have TestPasswordValidator.java and
PasswordValidator.java

2. Compile with: 
javac -classpath junit-4.8.2.jar:. TestPasswordValidator.java 

3. Run with:
java -classpath junit-4.8.2.jar:.  org.junit.runner.JUnitCore TestPasswordValidator