为什么这个输出在perl单元测试中重复？

我正在比较的输出字符串被复制，导致测试失败，但我不知道为什么

这是我的测试文件：

use lib ('./t/lib/');

use strict;
use warnings;

use Template;

use Test::More tests => 1;

# options/configuration for template
#my $config = {
     #PRE_PROCESS => 1, # means the templates processed can use the same global vars defined earlier
     #INTERPOLATE => 1,
     #EVAL_PERL => 1,
#    RELATIVE => 1,
#    OUTPUT_PATH => './out',

# };

my $template = Template->new();

# input string
my $text = "This is string number [% num %] ."; 

# template placeholder variables
my $vars = {
     num => "one",
 };

my $output = shift;

my $expected_output = "This is string number one .";

# processes input string and inserts placeholder values 
$template->process(\$text, $vars, \$output)
    || die "Template process failed: ", $template->error(), "\n";


# If process method is executed successfully it should have a return value of 1
diag($template->process(\$text, $vars, \$output));

# compares actual output with the expected output
is($output, $expected_output);

下面是我失败测试的输出：

t/68_template_test.t
t/68_template_test.t .. # 1
t/68_template_test.t .. 1/1 
#   Failed test at t/68_template_test.t line 45.
#          got: 'This is string number one .This is string number one .'
#     expected: 'This is string number one .'
# Looks like you failed 1 test of 1.
t/68_template_test.t .. Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/1 subtests 

---

我似乎无法发现这个bug，也无法找出发生这种情况的原因。

有两个调用

$template->process（\$text，\$vars，\$output）

我想你想要

my $rv = $template->process(\$text, $vars, \my $output);
ok($rv, "\$template->process ran successfully")
   and note($rv)
   or diag($template->error());

is($output, $expected_output, "\$template->process produced correct output");

---

有两个对

$template->process（\$text，\$vars，\$output）

的调用

我想你想要

my $rv = $template->process(\$text, $vars, \my $output);
ok($rv, "\$template->process ran successfully")
   and note($rv)
   or diag($template->error());

is($output, $expected_output, "\$template->process produced correct output");