Labour Market and CoS question

[Syntax30]

Hello all,
My student visa expires in 10 days and I may have a job offer coming my way. Unfortunately this would occur after my visa expires, which sucks because I'll now have to do the labour market test.

Out of curiosity, how long does it take to issue a CoS if you don't need the market test? Would it be possible to get a CoS issued and complete an online tier 2 application in a week?

If I have to do the labour market test, what is the process like? Advertise for 28 days and then what? How does the company prove no one is qualified? What proof do they need? Can they dismiss everyone just so they can get me? They would be doing it to hire me, however, I'm more than sure they can find plenty of qualified workers in the IT field, but can the company dismiss them all and say they aren't what they're looking for to hire me? Again what does the company need to do to prove this? How does the process work, and how long does it take to get a CoS??

Thanks.