fix: preserve scalar MakeMaker test rules

docs/about/changelog.md

@@ -10,6 +10,8 @@ priorities and future plans.
 
 - Dispatch bodyless `can` stubs through their class `AUTOLOAD` when present, preserving generated class introspection (#1959).
 
+- Preserve MakeMaker test rules when `MY::test` calls `SUPER::test` in scalar context.
+
 - Recognize boolean values as dual-valued in `Scalar::Util::isdual` (#1954).
 
 - Recognize a bareword filehandle when `print`'s implicit `$_` list ends at a block close (#1948).

src/main/perl/lib/ExtUtils/MakeMaker.pm

@@ -1921,7 +1921,7 @@ sub clean     { '' }
 sub test {
     my ($self) = @_;
     my $rule = $self->{_perlonjava_test_rule} || '';
-    return split /(?<=\n)/, $rule;
+    return wantarray ? split(/(?<=\n)/, $rule) : $rule;
 }
 sub top_targets { '' }
 

src/test/resources/unit/makemaker_scalar_my_test_super.t

@@ -0,0 +1,42 @@
+use strict;
+use warnings;
+use Test::More;
+use Config;
+use Cwd qw(getcwd);
+use File::Temp qw(tempdir);
+
+my $orig_dir = getcwd();
+my $tmpdir = tempdir(CLEANUP => 1);
+END { chdir $orig_dir if defined $orig_dir }
+chdir $tmpdir or die "chdir $tmpdir: $!";
+
+open my $marker, '>', 'Makefile.PL' or die "create Makefile.PL: $!";
+close $marker or die "close Makefile.PL: $!";
+mkdir 't' or die "mkdir t: $!";
+
+{
+    package MY;
+    sub test {
+        my $inherited = shift->SUPER::test(@_);
+        $inherited =~ s/\$\(TEST_FILES\)/-Iscalar-context \$(TEST_FILES)/;
+        $inherited;
+    }
+}
+
+use ExtUtils::MakeMaker;
+WriteMakefile(NAME => 'Local::ScalarSuperProbe', VERSION => '0.001');
+
+open my $makefile_fh, '<', 'Makefile' or die "open Makefile: $!";
+my $makefile = do { local $/; <$makefile_fh> };
+close $makefile_fh or die "close Makefile: $!";
+
+like($makefile, qr/-Iscalar-context \$\(TEST_FILES\)/,
+    'scalar-context SUPER::test retains and allows edits to the inherited rule');
+unlike($makefile, qr/^\d+\s*$/m,
+    'scalar-context SUPER::test does not become a bare list count');
+
+my $make = $Config::Config{make} || 'make';
+is(system($make, '-n', 'test'), 0,
+    'scalar-context MY::test output parses as a valid make target');
+
+done_testing();