Attached is a script which:

- Gets all the source code it can find from sys.modules
- Looks at every node in the parsed source
- Gets source text for that node using ast.get_source_segment
- Parses the source text again
- Compares the original node with the newly parsed node
- Points out if the nodes don't match

I ran this on Python 3.8.0, and it found several issues which have now been solved. So if there was a test like this then many bugs would have been caught earlier. I haven't tried it on a build of master, so I'm actually not sure which bugs have been fixed and what new bugs have been introduced.

The script partly relies on [asttokens](https://github.com/gristlabs/asttokens) which is another way to get the source code of a node. This helps to skip some known issues and to show what the output from get_source_segment should probably be. You don't strictly need to install asttokens to run the script but it's helpful.