Add a helper script for key file format conversion tests

As tests are done until now, there are a few scripts that look almost,
but not quite the same.  tkey, tx509, tcrl, tpkcs7, treq, tsid and
probably a few more.

recipes/tconversions.pl is a helper script that generalises the
function of each of those, and can then be used in a general manner
from test recipes.
Reviewed-by: NRich Salz <rsalz@openssl.org>

test/recipes/tconversion.pl

+#! /usr/bin/perl
+
+use strict;
+use warnings;
+
+use File::Compare qw/compare_text/;
+use File::Copy;
+use Test::More;
+use lib 'testlib';
+use OpenSSL::Test qw/:DEFAULT top_file/;
+
+my %conversionforms = (
+    "*"		=> [ "d", "p" ],
+    x509	=> [ "d", "n", "p" ],
+    );
+sub tconversion {
+    my $testtype = shift;
+    my $t = shift;
+    my @conversionforms = 
+	defined($conversionforms{$testtype}) ?
+	@{$conversionforms{$testtype}} :
+	@{$conversionforms{"*"}};
+    my @openssl_args = @_;
+    if (!@openssl_args) { @openssl_args = ($testtype); }
+
+    my $n = scalar @conversionforms;
+    my $totaltests =
+	1			# for initializing
+	+ $n			# initial conversions from p to all forms (A)
+	+ $n*$n			# conversion from result of A to all forms (B)
+	+ 1			# comparing original test file to p form of A
+	+ $n*($n-1);		# comparing first conversion to each fom in A with B
+    $totaltests-- if ($testtype eq "p7d"); # no comparison of original test file
+    plan tests => $totaltests;
+
+    my @cmd = ("openssl", @openssl_args);
+
+    my $init;
+    if (scalar @openssl_args > 0 && $openssl_args[0] eq "pkey") {
+	$init = ok(run(app([@cmd, "-in", $t, "-out", "$testtype-fff.p"])),
+		   'initializing');
+    } else {
+	$init = ok(copy($t, "$testtype-fff.p"), 'initializing');
+    }
+    if (!$init) {
+	diag("Trying to copy $t to $testtype-fff.p : $!");
+    }
+
+  SKIP: {
+      skip "Not initialized, skipping...", 22 unless $init;
+
+      foreach my $to (@conversionforms) {
+	  ok(run(app([@cmd,
+		      "-in", "$testtype-fff.p",
+		      "-inform", "p",
+		      "-outform", $to],
+		     stdout => "$testtype-f.$to")), "p -> $to");
+      }
+
+      foreach my $to (@conversionforms) {
+	  foreach my $from (@conversionforms) {
+	      ok(run(app([@cmd,
+			  "-in", "$testtype-f.$from",
+			  "-inform", $from,
+			  "-outform", $to],
+			 stdout => "$testtype-ff.$from$to")), "$from -> $to");
+	  }
+      }
+
+      if ($testtype ne "p7d") {
+	  is(compare_text("$testtype-fff.p", "$testtype-f.p"), 0,
+	     'comparing orig to p');
+      }
+
+      foreach my $to (@conversionforms) {
+	  next if $to eq "d";
+	  foreach my $from (@conversionforms) {
+	      is(compare_text("$testtype-f.$to", "$testtype-ff.$from$to"), 0,
+		 "comparing $to to $from$to");
+	  }
+      }
+    }
+    unlink glob "$testtype-f.*";
+    unlink glob "$testtype-ff.*";
+    unlink glob "$testtype-fff.*";
+}
+
+1;