Pulp should support more conservative dependency solving

[dparalen]

Description

Copying rpm units between repositories should only associate units that the target repository misses to satisfy any (versioned) dependencies. To give a real-life workflow example:

• create a fedora27 repository and populate it with the Fedora 27 content
• create a fedora28 repository and populate it with the Fedora 28 content
• create an empty repository foo
• recursively copy the glibc rpm from the fedora27 repository to the foo repository
• recursively copy the bash rpm from the fedora28 repository to the foo repository
• check that just the bash rpm was copied

Before pulp/pulp_rpm#1122, all the bash dependencies would have been pulled in because Pulp would have filtered the units based on their DB IDs rather than what they actually provide.

Notes

🐞 https://pulp.plan.io/issues/2478

Mind the content URLs above use a Brno Fedora content mirror

[RCMariko]

When testing this, please note original redmine issue on what repo dependencies were copied previously and will no longer would be copied - that detail is missing from the example above. Unit versions were mentioned in the original issue.

[dparalen]

@RCMariko thanks for checking!
Yeah this test would have been insufficient as the current Pulp implementation filters solver-identified units already present in the target repository: mea culpa, I haven't checked that before!

Updating the steps...

[Ichimonji10]

This is a Pulp 2 test case, correct?

[RCMariko]

Yes. 2.17.0 candidate.

[RCMariko]

@dparalen - I like those clarification - these details make more sense to me. Hopefully others agree/understand better. Thank you.

[rochacbruno]

@kersommoura @ragabala is this issue addressed by that CopyUnits test cases?

[nixocio]

There is already a test in place exploring this feature. CopyRecursiveUnitsTestCase