[backend] Introduce tests for workers code

Test the `bs_worker` code with `require_ok`.

Add the following tests for the `getsources` subroutine:
- Return result.
- Add 'materials' key to $buildinfo variable (used in the SLSA
  provenance generation).

src/backend/bs_worker

@@ -396,6 +396,7 @@ my $exitrestart;
 my $exitrestart_timeout = 300;	# wait max 5 minuntes
 
 exit(0) if @ARGV == 1 && $ARGV[0] eq '--selftest';
+return 1 if @ARGV == 1 && $ARGV[0] eq '--testcase';
 
 while (@ARGV) {
   usage(0) if $ARGV[0] eq '--help';

src/backend/t/1000-bs_worker.t

@@ -0,0 +1,57 @@
+#!/usr/bin/env perl
+
+use strict;
+use warnings;
+
+use Test::More tests => 3;
+
+
+use FindBin;
+use lib "$FindBin::Bin/lib/";
+
+use BSUtil;
+use Test::Mock::BSConfig;
+use Test::Mock::BSRPC;
+
+
+@::ARGV = ('--testcase');
+require_ok('./bs_worker');
+
+$BSConfig::bsdir = $FindBin::Bin;
+my $tmpdir = "$FindBin::Bin/tmp/1000";
+mkdir($tmpdir);
+
+my $buildinfo = {
+  srcserver  => $BSConfig::srcserver,
+  project    => 'project1',
+  package    => 'package1',
+  srcmd5     => 'f157738ddea737a2b7479996175a6cec',
+  verifymd5  => 'f157738ddea737a2b7479996175a6cec',
+};
+
+$Test::Mock::BSRPC::fixtures_map = {
+  "srcserver/getsources?project=project1&package=package1&srcmd5=$buildinfo->{srcmd5}"
+    => 'data/1000/srcserver/getsources',
+};
+
+my (@got, @expected);
+
+
+# getsources
+
+@got = getsources($buildinfo, $tmpdir);
+@expected = ('f157738ddea737a2b7479996175a6cec  package1');
+is_deeply(\@got, \@expected, 'getsources - Return value');
+
+my $expected = [
+                 {
+                   'digest' => {
+                     'sha256' => 'e237d5c5ea2b4dd327d2e103afd09572286609fbc9bf43cc9609f1371b4c8dd2'
+                   },
+                   'uri' => 'srcserver/source/project1/package1/hello_world.spec?rev=f157738ddea737a2b7479996175a6cec'
+                 }
+               ];
+is_deeply($buildinfo->{'materials'}, $expected, "getsources - Add 'materials' key to \$buildinfo");
+
+BSUtil::cleandir($tmpdir);
+rmdir($tmpdir);

src/backend/t/lib/Test/Mock/BSRPC.pm

@@ -57,7 +57,7 @@ BEGIN {
 
       my $receiver = $param->{'receiver'};
       if ($receiver) {
-	$ret = $receiver->(BSHTTP::str2req($ret), $param, $xmlargs || $param->{'receiverarg'}) if $receiver;
+        $ret = $receiver->(BSHTTP::str2req($ret), $param, $xmlargs || $param->{'receiverarg'});
       } elsif ($xmlargs) {
 	$ret = BSUtil::fromxml($ret, $xmlargs);
       }