Add a test for the minimum version of Perl

diff --git a/t/minimum-version.t b/t/minimum-version.t
new file mode 100755 (executable)
index 0000000..8872356
--- /dev/null
+++ b/t/minimum-version.t
@@ -0,0 +1,31 @@
+#!/usr/bin/perl
+#
+# Check that too-new features of Perl are not being used.
+#
+# Written by Russ Allbery <rra@stanford.edu>
+#
+# The authors hereby relinquish any claim to any copyright that they may have
+# in this work, whether granted under contract or by operation of law or
+# international treaty, and hereby commit to the public, at large, that they
+# shall not, at any time in the future, seek to enforce any copyright in this
+# work against any person or entity, or prevent any person or entity from
+# copying, publishing, distributing or creating derivative works of this work.
+
+use strict;
+use warnings;
+
+use Test::More;
+
+# Minimum version of Perl required.
+my $MINIMUM_VERSION = '5.006';
+
+# Skip tests if Test::MinimumVersion is not installed.
+if (!eval { require Test::MinimumVersion }) {
+    plan skip_all => 'Test::MinimumVersion required to test version limits';
+}
+Test::MinimumVersion->import;
+
+# Check most files in the Perl distribution.  Note that this doesn't check
+# examples or any other random directories with scripts, and there isn't any
+# simple way to add more directories.
+all_minimum_version_ok($MINIMUM_VERSION, { paths => [glob 'check_*'] });