title: Add main/java classes to my test/java directory in intellij
body: <p>I am new to intellij. I am switching from eclispe Kepler.</p>
  
  <p>I do not have a maven project, but I do have a maven directory structure. My classes are in src/main/java with my tests in src/test/java.</p>
  
  <p>My unit tests are complaining because they can't find the classes from src/main/java. What is the proper way to add this to the build path so that my unit tests can find the source?</p>