Hello team 👋 I had a question about how

install_from_resolve

works for different subsystems (namely

pytest

and

mypy

) in a repository with multiple resolves. For

pytest

, isn't it necessary for

pytest

to be installed in the same resolve as the code it is testing? What happens if the

install_from_resolve

for

pytest

conflicts with the resolve for the

pytest

target (for example, they have different interpreter constraints)? Where should type stubs be installed? Should it be installed in the

install_from_resolve

for

mypy

or in the resolve for that code? What if 2 different resolves use the same package at 2 different versions (which may have necessitated creating 2 separate resolves in the first place) and therefore need type stubs at 2 different versions? Thanks in advance!

Hi! Yes,

pytest

is ~unique among tools in that your tests might also import from it as a library. And if they do, then the versions need to be compatible. So while you could keep

pytest

in a separate resolve, and manually ensure that it is a subset of your code’s resolve, it’s probably easier to point

pytest

to your code’s resolve via `install_from_resolve`: https://www.pantsbuild.org/dev/docs/python/overview/lockfiles#sharing-lockfiles-between-tools-and-code

What happens if your code has multiple resolves? If you point to the pytest in one resolve, what is used in the other resolves? What happens if different resolves need different versions of pytest?

Yeah, that is tricky and not handled at the moment

Similar issue here...: https://pantsbuild.slack.com/archives/C046T6T9U/p1736061890760259

My code has multiple resolves and I tried to use

pytest.install_from_resolve

for one particular resolve for all resolves and this seemed to create a situations where dependencies from multiple resolves, often with conflicting versions, were installed into the same virtual environment. Suppose 2 of my resolves were named A and B. Resolve A uses

protobuf==3.7.0

and B uses

protobuf==4.25.6

. However, when running tests in resolve A, I saw

protobuf==4.25.6

installed. When I check,

google.protobuf.__path__

, I see a path in

named_caches

, which shows both directories

protobuf-3.17.2.dist-info

and

protobuf-4.25.6.dist-info

, which implies that both packages were installed and presumable 4.25.6 overwrote the install from 3.17.2. I saw this same problem with other packages (e.g.

pandas

version 1.2.4 and 1.5.3) and all other resolves other than the one used for

pytest.install_from_resolve

. Even if I wipe out all of

named_caches

and run tests in only the impacted resolve, I see the same problem. All of these problems go away if I create an additional resolve just for installing

pytest

. It appears that when using multiple resolves with conflicting versions, this is necessary.