EDIT: Also am I right in thinking that the reason this works is because I am calling that specific module with keys %My::Package::. If i am wrong please help me understand... more better :)

As a partial answer to this question, I've changed your module as follows:

# ...
use Exporter qw(import);
@EXPORT = (keys %My::Package::);  # @EXPORT instead of @EXPORT_OK
# ...
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And then I can run the test program without specifying the list of symbols to be imported:

$ perl -e '
 use strict;
 use warnings;
 use My::Package;

 test("hello world\n");
 test_2("hello this is dog");
'
hello world
hello this is dog
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So it seems that the work is really done within the module, which is exporting its symbols.