personally, i prefer eval "use $package" over manually messing with path names.

For the rest of the code, though, you don't need eval:

my $class = "Category::$classpart";
my $methodname = ....;

eval "use $class" or die; # die; propagates the current $@
my $handle = $class->new;
$handle->$methodname($key,$params,$testCase);
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