Switch to implicit (PEP 420) namespace.

[icemac]

Open issues:

• No tests are run

[dataflake]

Those small changes are all that's required?

[gforcada]

While testing it at work, I noticed the same, tests do not run.

Not sure if it is connected with zope.testrunner 🤔

[dataflake]

The problem is indeed zope.testrunner, specifically the following lines linked below. It's not compatible with implicit namespace packages because it will remove those folders from the test search path that do not contain an __init__.py, so in this particular case it will give up in the folder src/megrok because that does not contain the file anymore. Commenting out those lines will lead to a noticeable slowdown finding tests, but it does find and run them.

https://github.com/zopefoundation/zope.testrunner/blob/4f9048acb7f54677e6e6890b8491e069d136a2d6/src/zope/testrunner/find.py#L295-L299

[dataflake]

After checking again it looks like the perceived slowdown doesn't really exist. So the fix is in zope.testrunner's find.find_test_files_ function. Commenting out the offending lines breaks a number of zope.testrunner unit/doc tests, though. Unfortunately there's nothing in the local and global namespaces at that point in the code that could identify the folder named after the shared namespace so that it could be excluded from that shortcut, just like the folder where the search starts is excluded.

[icemac]

@dataflake Thank you for digging into the issue. I created a ticket for it: zopefoundation/zope.testrunner#160

[icemac]

@dataflake wrote:

Those small changes are all that's required?

Yes, I think so. But it has be done for all packages in a namespace at the same time. I chose this package to try out implicit namespaces because it is the only one in its namespace.

See also https://packaging.python.org/en/latest/guides/packaging-namespace-packages/

[dataflake]

In an experiment on a different package I had to add the following to the setup call to make it work, otherwise the release-check step could not build the package:

      package_dir={'': 'src'},

[icemac]

In an experiment on a different package I had to add the following to the setup call to make it work, otherwise the release-check step could not build the package:

      package_dir={'': 'src'},

This is what we usually do, so it is already in all setup.py files. It is also necessary for the pkg_resouces namespaces approach.

[dataflake]

I've done it the same way for my minor packages in the dataflake namespace and it worked out just fine. There's just a few so I changed them all at the same time and published releases. I am scared of doing this in the zope or Products namespace. That all needs to be closely coordinated for hundreds of packages.

[icemac]

@dataflake It will be a major update for all the packages. So not updating is still a possibility. And yes, it is a mayor effort, but it is nice to see that it is possible.