Upgrade RDFLib requirement

[amercader]

The current version of RDFlib won't work on Python 3.9 so we need to upgrade to RDFlib 6, which is not compatible with Python 2. The JSON-LD requirement has been integrated into the main rdflib package.

This adapts the tests so they can run across all RDFLib / Python / CKAN version 🤞

[amercader]

I finally managed to get all versions green 🙀
@seitenbau-govdata (and others) I'm fairly confident that the RDFlib upgrade won't break existing serializations and parsers but I'd be supergrateful if this PR could be tested in a real life instance with real metadata.

[seitenbau-govdata]

@amercader Sure, we can do that. We can test it in the environments CKAN 2.8 under Python 2.7 and CKAN 2.9 under Python 3.6.

[seitenbau-govdata]

@amercader Sorry, our environment (Ubuntu 18.04) is currently locked to Python 3.6. Unfortunately RDFlib 6 requires Python 3.7+, which means we cannot test this at the moment. Ubuntu 18.04 is supported until April 2023. So the only possible versions are rdflib in 5.0.0 and rdflib-jsonld in 0.6.2. But I don't know if the versions support Python 3.8+.

[amercader]

@seitenbau-govdata It's a tricky balance. I know that Ubuntu 18.04 might be supported for a while, but Python 3.6 is no longer supported and doesn't receive security updates any more. I'm keen on maximizing support for this extension but also using recent versions to minimize issues like #205.

If I understand correctly, users running on Python 3.6 can still use the extension if they install the requirements-py2.txt ones right? Obviously we need to document that on the README (and maybe rename the file to requirements-py2-py36.txt) but do you think this would be reasonable?

[seitenbau-govdata]

@amercader True, it's really tricky. Yes, the requirements in requirements-py2.txt still working under Python 3.6. I think this is a solution we can go with. Adding a hint in the documentation sounds good to me. Probably renaming the requirements file to requirements-py2-py36.txtmakes it even clearer than just documenting it on the README.

Currently we are testing the branch with the dependencies rdflib==5.0.0 and rdflib-jsonld==0.5.0 under CKAN 2.9 (Python 3.6) and CKAN 2.8 (Python 2.7). It wouldn't hurt to update the dependencies at the same time.

[seitenbau-govdata]

@amercader We have successfully tested the branch with the following environments

• CKAN 2.9.5 / Python 3.6
• CKAN 2.9.5 / Python 2.7
• CKAN 2.8.7 / Python 2.7

and the requirements rdflib==5.0.0 and rdflib-jsonld==0.5.0 in requirements-py2.txt.

But with Python 2.7 we suggest a downgrade in the dev-rquirements-py2.txt to responses==0.10.15, because there exists a version conflict with urllib3 between responses >= 0.10.15 and CKAN core Python 2 requirements.

ERROR: pip's legacy dependency resolver does not consider dependency conflicts when selecting packages. This behaviour is the source of the following dependency conflicts.
Successfully installed pytest-ckan-0.0.12 responses-0.17.0 urllib3-1.26.9
requests 2.22.0 requires urllib3!=1.25.0,!=1.25.1,<1.26,>=1.21.1, but you'll have urllib3 1.26.9 which is incompatible.

https://github.com/ckan/ckanext-dcat/runs/6289349808?check_suite_focus=true#step:5:100

This become an issue if the requirement ckanext-harvest is installed before ckanext-dcat. In the GitHub actions the ckanext-harvest is installed after ckanext-dcat so the version is replaced by a CKAN core compatible version.

Requirement already satisfied: idna<2.9,>=2.5 in /usr/lib/python2.7/site-packages (from requests>=2.11.1->-r ckanext-harvest/pip-requirements.txt (line 5)) (2.8)
Collecting urllib3!=1.25.0,!=1.25.1,<1.26,>=1.21.1
  Downloading urllib3-1.25.11-py2.py3-none-any.whl (127 kB)
Installing collected packages: pika, pyOpenSSL, urllib3
  Attempting uninstall: urllib3
    Found existing installation: urllib3 1.26.9
    Uninstalling urllib3-1.26.9:
      Successfully uninstalled urllib3-1.26.9
Successfully installed pika-1.2.1 pyOpenSSL-18.0.0 urllib3-1.25.11

https://github.com/ckan/ckanext-dcat/runs/6289349808?check_suite_focus=true#step:6:63

[seitenbau-govdata]

@amercader And we need a rebase to the current master and adding the self._add_responses_solr_passthru() to the new tests

• test_harvest_default_file_size
• test_harvest_config_file_size

[seitenbau-govdata]

@amercader 👍 LGTM, thanks!

[amercader]

Thanks @seitenbau-govdata ! I've incorporated all your suggested changes, I think that gives a good support across versions, I'll release a new version with this and your other recent changes.