Allow users to provide an LWP::UserAgent based browser.

Makefile.PL

@@ -20,6 +20,7 @@ WriteMakefile(
 	'Carp' 	     => 0,
 	'Data::Dumper' => 0,
 	'HTTP::Request' => 0,
+	 'Safe::Isa'     => 1.000005,
 	'strict' 	=> 0,
 	'warnings'	=> 0
     },

lib/WebService/Instagram.pm

@@ -10,6 +10,7 @@ use URI;
 use Carp;
 use Data::Dumper;
 use HTTP::Request;
+use Safe::Isa;
 
 our $VERSION = '0.05';
 
@@ -18,7 +19,10 @@ use constant ACCESS_TOKEN_URL 	=> 'https://api.instagram.com/oauth/access_token?
 
 sub new {
 	my ($class, $self) = @_;
-	$self->{browser} = LWP::UserAgent->new();
+	$self->{browser} ||= LWP::UserAgent->new();
+	unless ( $self->{browser}->$_isa('LWP::UserAgent') ) {
+		carp 'Browser is not a LWP::UserAgent';
+	}
 	bless $self, $class;
 	return $self;
 }

t/01-browser.t

@@ -0,0 +1,17 @@
+package MyUserAgent;
+
+use base 'LWP::UserAgent';
+
+1;
+package main;
+
+use Test::More;
+
+use WebService::Instagram;
+my $instagram = WebService::Instagram->new( {browser => MyUserAgent->new });
+
+isa_ok( $instagram->{browser}, 'MyUserAgent' );
+use DDP;
+p $instagram;
+
+done_testing;