Here is my mushroom farm. This one is almost a month old and it is already fruiting.
Mushroom do not use light during it colonization, like plants using it for photosynthesis. Instead, light gives signal to the fungus to start fruiting.
Colonization was done in the absent of light with the help of black nylon covered all over the wall and roof to ensure no light penetrates the room used.
The oyster mushroom fruiting: