I'll not repeat what has been said about this operator in list or scalar context, as this is clear enough IMHO, but if you are looking for brevity, you could combine lines 3, 4 and 5 of your first code snippet this way:

print "parse = $1\n" if $test_line =~/(Happy).*/;
[download]

And notice how the syntax here is explicitly using the Boolean value returned by the regex.