Laravel gate error, no such table: permissions (SQL: select * from “permissions”)

For laravel testing environment, Laravel gate is not working. In phpunit.xml file, I am using sqlite connection and :memory: as database.

<env name="DB_CONNECTION" value="sqlite"/>
<env name="DB_DATABASE" value=":memory:"/>

In AuthServiceProvider, I am defining gate as in this code below.

public function boot(GateContract $gate)
{
    $this->registerPolicies($gate);


    foreach($this->getPermissions() as $permission) {
        $gate->define($permission->name, function($user) {
            $user->hasRole($permission->roles);
        });
    }
}

protected function getPermissions() {
    return Permission::with('roles')->get();
}

So, when ever I run phpunit. It shows error no such table: permissions (SQL: select * from "permissions").

So, please guide how can I define gate after migration for testing environment.