Checks the stock level for the attribute combination the user has selected before adding the product to the cart.
If the quantity is higher than the available stock the form errors with a helpful message.
Products with no attributes
Products with 1 attribute
products with multiple attributes (required and optional)
I don't know how much use this will be as a module or even if it's duplicated... perhaps someone could tell me.
I need it on a regular basis as I don't know of another way of achieving this.