// user class
class User extends Authenticatable
{
    use Notifiable;

    protected $fillable = [
        'name', 'email', 'password',
    ];

    protected $hidden = [
        'password', 'remember_token',
    ];

    protected $casts = [
        'settings' => 'array'
    ];
}


// migration
public function up()
{
    Schema::create('users', function (Blueprint $table) {
        $table->increments('id');
        $table->string('name');
        $table->string('email')->unique();
        $table->string('password');
        $table->json('settings')->nullable();
        $table->rememberToken();
        $table->timestamps();
    });
}

// test
public function testCanVerifyJsonColumn()
{
    $expectedData = [
        'profile_picture' => 'profile picture',
    ];

    $user = factory(User::class)->create([
        'settings' => $expectedData
    ]);

    $this->assertDatabaseHas('users', [
        'settings' => json_encode($expectedData),
    ]);
}