Anonymous subs to the rescue:

#!/usr/bin/perl
use warnings;
use strict;

{   package MyPackage;

    sub method1 { '<?xml version="1.0"?>' }

    sub method2 { '[?xml version="2.0"?][a][/a]' }

}


use Test::More;

sub my_subtest {
    like( shift, qr/xml version=/, "XML Document");
   # more tests on XML document text here....
}

for my $method (qw/method1 method2/) {
    subtest "Checking $method" => sub { my_subtest(MyPackage->$method)
+ };
}
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Update: Unfortunately, I am not able to use a sub returning a sub as in

sub new_test {
    my ($test, $method) = @_;
    return sub { $test->(MyPackage->$method) };
}


for my $method (qw/method1 method2/) {
    subtest "Checking $method", new_test(\&my_subtest, $method);
}
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I am getting

Type of arg 2 to Test::More::subtest must be sub {} (not subroutine en
+try)
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