[Bug]: py_library instances from generated repositories are not found by py_test (bzlmod)

[wade-arista]

What happened?

I'm using bzlmod in bazel 7.0.2.

I created a basic repository_rule that creates a rules_py py_library. I then created a simple test that specifies the external repository in its deps and tries to import this py_library (foo). It doesn't find the python package. If I access other rules_py py_library instances from my _main repo, instead, those are found as expected.

graph TD;
test(:test) --> baz(direct:baz)
test --> foo("@myrepo//:foo")
test --> bar("@myrepo//bar")
    subgraph "@myrepo"
    foo
    bar
    end

Loading

Version

Development (host) and target OS/architectures: linux x86_64 "Ubuntu 22.04.3 LTS"

Output of bazel --version:

Bazelisk version: v1.19.0
Build label: 7.0.2
Build target: @@//src/main/java/com/google/devtools/build/lib/bazel:BazelServer
Build time: Thu Jan 25 16:13:35 2024 (1706199215)
Build timestamp: 1706199215
Build timestamp as int: 1706199215

Version of the Aspect rules, or other relevant rules from your
WORKSPACE or MODULE.bazel file:

bazel_dep(name = "rules_python", version = "0.31.0")
bazel_dep(name = "aspect_rules_py", version = "0.5.0")

Language(s) and/or frameworks involved:
Python3

How to reproduce

I have a minimal repro here:

https://github.com/wade-arista/bazel-demo/tree/63fc4391a7c30be0587a642649b0c16514fab302/rules_py_reporule

test:

import baz
import foo
import bar

BUILD.bazel

load("@aspect_rules_py//py:defs.bzl", "py_test")

py_test(
    name = "test",
    srcs = ["test.py"],
    deps = [
        "//rules_py_reporule/direct/baz",
        "@myrepo//:foo",
        "@myrepo//bar",
    ],
)

py_test(
    name = "all_direct",
    srcs = ["test.py"],
    main = "test.py",
    deps = [
        "//rules_py_reporule/direct/baz",
        "//rules_py_reporule/imported:foo",
        "//rules_py_reporule/imported/bar",
    ],
)

for @myrepo:

importer = use_extension("//rules_py_reporule/rules:import.bzl", "importer")
use_repo(importer, "myrepo")

Any other information?

Using ctx.label.workspace_name when making the import path, when it is non-empty, fixes the issue.

--- a/py/private/py_library.bzl
+++ b/py/private/py_library.bzl
@@ -86,7 +86,7 @@ def _make_import_path(label, workspace, base, imp):
 def _make_imports_depset(ctx):
     base = paths.dirname(ctx.build_file_path)
     import_paths = [
-        _make_import_path(ctx.label, ctx.workspace_name, base, im)
+        _make_import_path(ctx.label, ctx.label.workspace_name or ctx.workspace_name, base, im)
         for im in ctx.attr.imports
     ] + [
         # Add the workspace name in the imports such that repo-relative imports work.

Here's the contents of the test's runfiles directory:

./bazel-out/k8-fastbuild/bin/rules_py_reporule/test.runfiles/test.venv
./bazel-out/k8-fastbuild/bin/rules_py_reporule/test.runfiles/_main~importer~myrepo
./bazel-out/k8-fastbuild/bin/rules_py_reporule/test.runfiles/bazel_tools
./bazel-out/k8-fastbuild/bin/rules_py_reporule/test.runfiles/rules_python~0.31.0~python~python_3_11_x86_64-unknown-linux-gnu
./bazel-out/k8-fastbuild/bin/rules_py_reporule/test.runfiles/_main

So in this case, ctx.label.workspace_name is _main~importer~myrepo for e.g. @myrepo//bar, but ctx.workspace_name is just _main, so we need to use the former when building the runfiles import paths.