How can I mock %ENV in Perl tests?

Question

I'm trying to retrofit some tests using Test::More to legacy code and I've bumped into a bit of a snag. I don't seem to be able to set %ENV in the test module. The called function definitely uses this variable so %ENV doesn't seem to be carried across to the test object.

#!/usr/bin/perl

use strict; use warnings;
use Test::More qw(no_plan);

BEGIN {
    $ENV{HTTP_WWW_AUTHENTICATE} = 
        'WWW-Authenticate: MyType realm="MyRealm",userid="123",password="abc"';
    use_ok('Util');
}

$ENV{HTTP_WWW_AUTHENTICATE} = 
    'WWW-Authenticate: MyType realm="MyRealm",userid="123",password="abc"';

printf qq{get_authentication_info = "%s"\n}, get_authentication_info();
ok(get_authentication_info(), 'Get authentication info');

I keep getting...

perl t\Util.t
ok 1 - use Util;
Use of uninitialized value in concatenation (.) or string at t\Util.t line 14.
get_authentication_info = ""

As with all things Perl, I'm pretty sure that some one has done this before.

UPDATE: Thanks to all for your help

The problem was between the keyboard & chair ... My test data was just plain wrong It needed to be

$ENV{HTTP_WWW_AUTHENTICATE} = 
    'MyType realm="MyRealm",userid="123",password="abc"';

Answer 1

Why are the lines setting $ENV{HTTP_WWW_AUTHENTICATE} commented out?

Also, what are the specs for get_authentication_info()?

Answer 2

As Sinan said, the $ENV{...} lines are commented out, so it can't work. But if you want really testable code, I'd suggest to make the get_authentication_info function take a hash as an argument. That way you can test it without setting the global variable, and in the real code you can pass the real enviromnent hash. Global state will always become a problem eventually.

Answer 3

Agreed with Lukáš -- get your global environment (and perform validity checks etc) all in one place, such as in its own method, and then pass those values to all other methods that need it. That way in your unit tests you can just drop in a replacement method that determines the environment and config variables in a different way (such as from a file, or directly set at the top of your test script).

Answer 4

Try setting the env variable before BEGIN.

If not try this:

1. First, go to a command prompt and set the env var there. Then run your script. If the tests pass. Then as you predicted, the problem is with setting the env var.

2. If the tests fail, then the problem lies some where else (probably in get_authentication_info).

Answer 5

What does

get_authentication_info()

return?

My guess is nothing.

If this is always true, then line 14 will always return the "Use of uninitialized value..." warning.

If you expect a value, you need to investigate why get_authentication_info() is failing?