java - Trying to use Junit to verify console output matches a string

I'm trying to use Junit to verify that something output by
a method matches a string using assertequals, but I can't get it to work. Because it
says that the test case is undefined for (String, Void) My code for the method is
below

public void
            speciesInformation() {
 switch (species){ 


            case"Penguin":System.out.println("Penguin Trivia fact");

            break;

 default: System.out.println("There is no current
            information for that species");
 break;
 }
            
}

and
the junit code I'm attempting to use is(other tests
omitted):

public class AnimalsTest
            extends junit.framework.TestCase{
public void testSpeciesInfo() { 

            assertEquals(" Penguin Trivia fact/n",
            penguin.speciesInformation());
}
}

All
my other tests work because they're based on a return, but this one is supposed to be
based on what's printed by the public void method and I can't tell how to do it or find
information on how.