Code-Test-Code cycle in Amazong Cloud (AWS)

Code-Test-Code cycle in Amazong Cloud (AWS)

I new to Amazon AWS and want to create a cloud-based REST API in Node.js.
Usually I develop the program along with testing it. It means I write some
tests, and then write the code that makes those tests run successfully. So
in a typical programming session, I may run the tests or the app tens of
times.
When I do this locally it is easy and quick. But what if I want to do the
whole process on Amazon cloud? How does this code-test-code cycle look
like? Should I upload my code to AWS every time I make a change? And then
run it against some server address?
I read somewhere in the documentation that when I run a task for a few
minutes (for example 15min), Amazon rounds it up to 1hour. So if in a
typical development session I run my program 100 times in an hour, do I
end up paying for 100 hours? If yes, then what will be the solution to
avoid these huge costs?