test.pl

#! /usr/bin/env perl


use strict;
use warnings;

use File::Basename;
use File::Path;
use File::Slurp;

my $channelName = "nixos-unstable";

# configuration
my $channelsDir = "/Users/samuel/tmp/tmp/data/releases/channels";

my $releasePrefix = "FOO"; # unimportant!
my $target = "https://releases.nixos.org/$releasePrefix";

# THIS IS OUT OF ORDER FROM REALITY!

# This test file tests the behaviour of re-reading the file.

# https://github.com/NixOS/nixos-channel-scripts/blob/e9587f93887292a5d7252bc60bae09ed7c3e3f27/mirror-nixos-branch.pl#L217-L221
my $channelLink = "$channelsDir/$channelName";
if ((read_file($channelLink, err_mode => 'quiet') // "") ne $target) {
    write_file("$channelLink.tmp", "$target");
    rename("$channelLink.tmp", $channelLink) or die;
}

# https://github.com/NixOS/nixos-channel-scripts/blob/e9587f93887292a5d7252bc60bae09ed7c3e3f27/mirror-nixos-branch.pl#L74-L81
my $curReleaseDir = readlink "$channelsDir/$channelName";
if (defined $curReleaseDir) {
    my $curRelease = basename($curReleaseDir);
    print "Wanted: $releasePrefix Got: $curRelease\n";
}
else {
	print "!! curReleaseDir unset!\n"
}

my @releaseUrl = split(/\//, read_file("$channelsDir/$channelName", err_mode => 'quiet') // "");
my $curRelease = pop @releaseUrl;
print "Wanted: $releasePrefix Got: $curRelease\n";

if ($curRelease eq $releasePrefix) {
	print "🎉";
}