JUnit test classes not showing up in JMeter

You must put your junit classes in lib/junit folder as you did and dependencies in lib folder.

You shouldn't use fatjar as sometimes these tools removed files from meta-inf or only keep one from all jars, spring pûts one in each of its jars .

Add all your jars one by one in lib folder.

Check jmeter logs to see if you have any exception .

If it still fails, ask a question on jmeter user list and if you don't get any answer create a simple test case and open a bug.

Did you check the option that JUnit sampler has to search for v4 tests?

I've tried and this works for a simple project I've created with JUnit 4, it filters only tests with the @Test annotations even those classes doesn't extend TestCase class.