如何伪造输入到perl的钻石操作员？ [英] How to fake input to perl's diamond operator?

问题描述

此问题的答案描述了如何伪输入< STDIN> 。我的目标类似于这个问题：我的单元测试需要假输入<> 。

The answers to this question describe how to fake input to <STDIN>. My goal is similar to that question: my unit test needs to fake input to <>.

我使用相同的技术假冒<> 的输入，它不起作用。 <> 的介绍级解释让我相信，当命令行上没有给出文件时，它正在从STDIN读取，但这似乎没有是这样的。

When I apply the same technique to fake input to <>, it doesn't work. The introductory-level explanations of <> led me to believe that it was reading from STDIN when no files are given on the command line, but this doesn't seem to be the case.

我正在努力工作的样本：

The sample I'm trying to make work:

#!/usr/bin/perl -w

use strict;
use warnings;
use Carp;
use English qw( -no_match_vars );

sub fake1 {
    my $fakeinput = "asdf\n";
    open my $stdin, '<', \$fakeinput
      or croak "Cannot open STDIN to read from string: $ERRNO";
    local *STDIN = $stdin;

    my $line = <>;
    print "fake1 line is $line\n";

    return 0;
}

sub fake2 {
    my $fakeinput = "asdf\n";
    open my $stdin, '<', \$fakeinput
      or croak "Cannot open STDIN to read from string: $ERRNO";
    local *STDIN = $stdin;

    my $line = <STDIN>;
    print "fake2 line is $line\n";

    return 0;
}

fake1();
fake2();

fake2 有效， fake1 没有。一个示例会话（qwerty是我打字）：

fake2 works, fake1 does not. A sample session (the "qwerty" is me typing):

$ perl /tmp/diamond.pl
qwerty
fake1 line is qwerty

fake2 line is asdf

我的问题：

1. 如何伪造输入<> ？


2. <> 和< STDIN> 之间有什么区别？文件在命令行中给出？ （即为什么链接问题中的技术适用于< STDIN> 但不适用于<> ？ ）

1. How can I fake input to <>?
2. What's the difference between <> and <STDIN> when no files are given on the command line? (I.e. Why does the technique in the linked question work for <STDIN> but not for <>?)

谢谢。

推荐答案

在第一次测试中试试这个：

Try this in your first test:

open ARGV, '<', \$fakeinput
      or croak "Cannot open STDIN to read from string: $ERRNO";

my $line = <>;
print "fake1 line is $line\n";

这样做的缺点是不是本地 - 不知道你是否可以在本地制作。
（你可以多次这样做，在每次测试前重置。）

This has the disadvantage of not being "local" - no idea if you can make it local or not. (You can do that several times though, resetting before each test.)

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