Laravel4 Seeding in testing environment fails using SQLite, while succeeds using mysql

In short: seeding is working fine with mysql while breaks with sqlite. The broken code is like DB::table('user')->insert($users);

Seed code:

<?php
public function run() {
    DB::table('user')->delete();
    $users = array();
    $birth = new DateTime('1980-03-12');
    while ($i++ < 50) {
        $users[$i]['email'] = "[email protected]";
        $users[$i]['password'] = User::password('test');
        $users[$i]['enabled'] = 1;
        $users[$i]['name'] = 'Name';
        $users[$i]['surname'] = 'Surname';
        $users[$i]['birthDate'] = $birth;
    }
    DB::table('user')->insert($users); //<- This line is broken when using sqlite.
}

My default database driver is mysql, now i am trying to switch to sqlite for the testing environment. So, under

app/config/testing/database.php

i have this config, inside 'connections' ('default' key is 'sqlite')

'sqlite' => array(
            'driver'   => 'sqlite',
            'database' => ':memory:',
            'prefix'   => '',
        ),

Now, if i issue

php artisan migrate --seed, this is working fine.

If i issue

php artisan migrate --seed --env=testing, this is NOT working

The DB::table('user')->insert($users); above is failing, infact when i comment that out the seeding works fine. The error at command line is

ErrorException","message":"array_keys() expects parameter 1 to be array, null given [...] /laravel/framework/src/Illuminate/Database/Query/Grammars/SQLiteGrammar.php","line":52

What's wrong here?

Copyright Notice：Content Author:「brazorf」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/19170649/laravel4-seeding-in-testing-environment-fails-using-sqlite-while-succeeds-using