Use a src/ layout

[jwodder]

Part of #325.

The changes to the *.py files are due to isort (via pre-commit) now putting absolute nidm imports in the proper location; they were in the wrong location before because the isort config I copied assumed a src/ layout.

[jwodder]

@yarikoptic Please merge this soon.

[yarikoptic]

In general I prefer to not mess with src/'ing it and just have things straight under the packagename/. Please remind me why we would like that. E.g. is that to prevent using the nidm package without first building it, which would be needed for proper version assignment (if we are to use versioningit or alike)? or is there is more to it?

[jwodder]

@yarikoptic The src/ layout helps ensure that testing happens against an installed copy of your package rather than the copy in the repository, thereby letting you catch packaging errors. There are other benefits as well, mostly around making it easier to package exactly what you want; see https://blog.ionelmc.ro/2014/05/25/python-packaging/ and a web search for more information.

(Also, this reminded me that, when using a src/ layout, either the tests should be in their own top-level directory or else the --pyargs option has to be passed to pytest; I'm going with the former.)

[yarikoptic]

either the tests should be in their own top-level directory or else the --pyargs option has to be passed to pytest; I'm going with the former.)

I thought to argue, but since you did keep the hierarchical organization, my argument no longer holds, so ok, lets' do it your way.

[github-actions]

🚀 PR was released in v4.0.0 🚀