Compiling a JUnit test class is like compiling any other Java classes. The only thing you need watch out is that the JUnit JAR file must be included in the classpath. For example, to compile the test class HelloTest.java described previously, you should do this:
javac -cp junit-4.4.jar HelloTest.java
dir HelloTest.*
453 HelloTest.class
183 HelloTest.java
The compilation is ok, if you see the HelloTest.class file.