.gitignore

*.class

AA.java

public class AA {
    public int func(int x) {
        return x + 2;
    }
}

Makefile

do : build
	scala test.scala
	echo :l test.scala | scala

build: AA.class

AA.class : AA.java
	javac $^

clean :
	$(RM) $(RMF) *.class

test :
	prove ./test.pl

test.pl

#!/usr/bin/env perl

use strict;
use warnings;

use Test::More tests => 2;

my $expect = <<"EOL";
12
EOL

is(`scala test.scala`, $expect);
{
    my $ret = `echo :l test.scala | scala`;
    $ret =~ s/\A.*aa:[^\n]+[\n]+//ms;
    $ret =~ s/scala> //ms;
    chomp($ret);
    is($ret, $expect);
}

test.scala

val aa = new AA;
println(aa.func(10))