+#####
+
+$customer = new_customer()->save;
+%data = (
+ customernumbers => ['a fantasy', $customer->number],
+);
+
+$db_obj = SL::DB::BackgroundJob->new();
+$db_obj->set_data(%data);
+$job = SL::BackgroundJob::ConvertTimeRecordings->new;
+
+$err_msg = '';
+eval { $ret = $job->run($db_obj); 1; } or do {$err_msg = $@};
+ok($err_msg =~ '^Not all customer numbers are valid', 'wrong customer number detected');
+
+#####
+
+%data = (
+ customernumbers => '123',
+);
+
+$db_obj = SL::DB::BackgroundJob->new();
+$db_obj->set_data(%data);
+$job = SL::BackgroundJob::ConvertTimeRecordings->new;
+
+$err_msg = '';
+eval { $ret = $job->run($db_obj); 1; } or do {$err_msg = $@};
+ok($err_msg =~ '^Customer numbers must be given in an array', 'wrong customer number data type detected');
+
+#####
+
+%data = (
+ part_id => '123',
+);
+
+$db_obj = SL::DB::BackgroundJob->new();
+$db_obj->set_data(%data);
+$job = SL::BackgroundJob::ConvertTimeRecordings->new;
+
+$err_msg = '';
+eval { $ret = $job->run($db_obj); 1; } or do {$err_msg = $@};
+ok($err_msg =~ '^No valid part found by given part id', 'invalid part id detected');
+
+#####
+
+$part = new_service(partnumber => 'Serv1', unit => 'Std', obsolete => 1)->save;
+%data = (
+ part_id => $part->id,
+);
+
+$db_obj = SL::DB::BackgroundJob->new();
+$db_obj->set_data(%data);
+$job = SL::BackgroundJob::ConvertTimeRecordings->new;
+
+$err_msg = '';
+eval { $ret = $job->run($db_obj); 1; } or do {$err_msg = $@};
+ok($err_msg =~ '^No valid part found by given part id', 'obsolete part detected');
+
+#####
+
+%data = (
+ project_id => 123,
+);
+
+$db_obj = SL::DB::BackgroundJob->new();
+$db_obj->set_data(%data);
+$job = SL::BackgroundJob::ConvertTimeRecordings->new;
+
+$err_msg = '';
+eval { $ret = $job->run($db_obj); 1; } or do {$err_msg = $@};
+ok($err_msg =~ '^No valid project found by given project id', 'invalid project id detected');
+
+#####
+
+$project = create_project(projectnumber => 'p1', description => 'Project 1', valid => 0)->save;
+%data = (
+ project_id => $project->id,
+);
+
+$db_obj = SL::DB::BackgroundJob->new();
+$db_obj->set_data(%data);
+$job = SL::BackgroundJob::ConvertTimeRecordings->new;
+
+$err_msg = '';
+eval { $ret = $job->run($db_obj); 1; } or do {$err_msg = $@};
+ok($err_msg =~ '^No valid project found by given project id', 'invalid project detected');
+
+#####
+