I\'ve got the following structure
lib/junit-4.10.jar
tests/Tester.java
tests/Tester.class
build/jar/jar_file.jar
(Tester belongs to package tes
Assuming this is Linux/Mac (not Windows) and your path separator is correct (:), since your test class files exist in package subdirectories under the current working directory (.) You need to add "." to your class path, for example:
java -cp .:build/jar/jar_file.jar:lib/junit-4.10.jar org.junit.runner.JUnitCore tests.Tester