Add spec for `mode` value validation
Add spec for `mode` value validation

naiyt/huginn,dsander/huginn,gautamkrishnar/huginn,breandan/huginn,cantino/huginn,mathias/huginn,huginn/huginn,breandan/huginn,virtadpt/huginn,huginn/huginn,brianpetro/huginn,gautamkrishnar/huginn,brianpetro/huginn,strugee/huginn,strugee/huginn,Ishfal/huginn,gautamkrishnar/huginn,Ishfal/huginn,virtadpt/huginn,dsander/huginn,huginn/huginn,eugenesvk/huginn,eugenesvk/huginn,naiyt/huginn,mathias/huginn,dsander/huginn,Ishfal/huginn,brianpetro/huginn,virtadpt/huginn,naiyt/huginn,eugenesvk/huginn,strugee/huginn,breandan/huginn,cantino/huginn,cantino/huginn,mathias/huginn