Add isolated tests for Mohawks include-default patch

t/maniskip.include-default.t

@@ -0,0 +1,44 @@
+use strict;
+use warnings;
+
+use Test::More tests => 3;
+use ExtUtils::Manifest qw( maniskip );
+
+# ABSTRACT: Ensure include-default is memory only
+
+use lib 't/tlib';
+use Test::TempDir::Tiny qw( in_tempdir );
+
+sub _spew {
+    my ( $filename, $content ) = @_;
+    open my $fh, '>', $filename or die "Can't open $filename for writing. $!";
+    print {$fh} $content or die "Error writing to $filename. $!";
+    close $fh or die "Error closing $filename. $!";
+}
+
+sub _slurp {
+    my ($filename) = @_;
+    my $content;
+    open my $fh, '<', $filename or die "Can't open $filename for reading. $!";
+    local $/ = undef;
+    $content = <$fh>;
+    close $fh or warn "Error closing $filename. $!";
+    return $content;
+}
+
+in_tempdir 'noexpansions' => sub {
+
+    _spew( 'MANIFEST.SKIP', qq[#!include_default] );
+
+    my $skipchk = maniskip();
+
+    my $skipcontents = _slurp('MANIFEST.SKIP');
+
+    unlike( $skipcontents, qr/#!start\s*included/,
+        'include_default not expanded on disk' );
+
+    ok( $skipchk->('Makefile'), 'Makefile still skipped by default' );
+    ok( !$skipchk->('Makefile.PL'),
+        'Makefile.PL still not skipped by default' );
+};
+done_testing;