Testing AWS spot inastances

My company is looking to switch to using Spot pricing when provisioning EC2 instances. I've been tasked with writing some unit tests that test things such as:

• Our Spot instance count in at a certain threshold
• When that threshold isn't met on demand replacements are brought up to replace them

I'm not an adept tester and haven't had much exposure to AWS on the whole. So my question is what approach, tools, software could I use to begin implementing this? My initial thinking is to write a bash script with AWS CLI commands and go from there.

Any pointers or recommendations would be greatly appreciated!