add test to make sure MANIFEST contains all the libs

Makefile.PL

@@ -41,18 +41,20 @@ WriteMakefile(
   },
 
   PREREQ_PM    => {
-    'Scalar::Util'           => 1.48,
-    'Test::More'             => '0.96', # need done_testing (0.88) and subtests (0.95_01)
-    'Digest::MD5'            => 0,
+    'Cwd'                    => 0,
     'DBM::Deep'              => 2.0008,
     'Devel::CheckOS'         => '1.83',
-    'Test::utf8'             => 0,
+    'Digest::MD5'            => 0,
+    'File::Basename'         => 0,
+    'File::Find::Rule'       => 0,
     'File::ShareDir'         => 1.104,
     'File::Spec'             => 0,
-    'File::Basename'         => 0,
-    'Cwd'                    => 0,
-    'I18N::LangTags::Detect' => 0,
     'I18N::LangTags'         => 0,
+    'I18N::LangTags::Detect' => 0,
+    'Scalar::Util'           => 1.48,
+    'Test::Differences'      => 0.62,
+    'Test::More'             => '0.96', # need done_testing (0.88) and subtests (0.95_01)
+    'Test::utf8'             => 0,
   },
   dist => {
     PREOP => "./build-data.sh --previoustag"

t/manifest-contains-all-modules.t

@@ -0,0 +1,20 @@
+use strict;
+use warnings;
+
+use File::Find::Rule;
+
+use Test::More;
+use Test::Differences;
+
+open(my $manifest_fh, '<', 'MANIFEST') || die("Couldn't open MANIFEST: $!\n");
+my @manifest = sort grep { /^lib.*\.pm$/ } map { chomp; $_ } <$manifest_fh>;
+my @files = sort File::Find::Rule->file()->name('*.pm')->in('lib');
+
+eq_or_diff(
+    \@manifest,
+    \@files,
+    "MANIFEST and lib/**/*.pm match",
+    { filename_a => 'MANIFEST', filename_b => 'lib/**/*.pm' }
+);
+
+done_testing();