How to determine lowest version of Python 3 to run?

[MRAB]

On 2017-10-05 03:23, Christopher Reimer wrote:
> Greetings,
> 
> I've always installed the latest and greatest version of Python 3 to develop my own programs. I'm planning to release a program to the public. I could toss in a note that the program runs on the latest version of Python 3.6 but I haven't tested on earlier versions (i.e., 3.4 and 3.5). AFAIK, I haven't written any version-specific code.
> 
> How do I determine the lowest version of Python to run?
> 
> I'm leaning towards installing the latest minor version of each available major version, running tox to run the unit tests against each one, and seeing what blows up.
> 
> Thank you,
> 
If you want to know whether it'll run on 3.4, just run it on 3.4.
There may not be much point in running it on 3.5 because if it's OK on 
3.4, then it should also be OK on 3.5.

Of course, if you're talking about stuff that needs to be compiled, such 
as an extension written in C, then you'll need to test it on every 
version that you're willing to support.