Replace deprecated pkg_resources and pin setuptools

setuptools v82.0.0 removed the deprecated pkg_resources. Our
Dockerfile installs the most recent version of build tools, including
setuptools, which breaks tests.

We can fix the tests to use importlib instead of pkg_resources.
However, we still can't just install the latest setuptools, because
various packages also depend on a version that still includes
pkg_resources, so we pin it to <82.0.0.

Author: rebkwok

Dockerfile

@@ -36,8 +36,9 @@ RUN python3 -m venv /opt/venv
 # "activate" the venv
 ENV VIRTUAL_ENV=/opt/venv/ PATH="/opt/venv/bin:$PATH"
 # We ensure up-to-date build tools (which why we ignore DL3013)
+# Pin setuptools to <82.0.0 (which removed pkg_resources, which some dependencies require)
 # hadolint ignore=DL3013,DL3042
-RUN --mount=type=cache,target=/root/.cache python -m pip install -U pip setuptools wheel pip-tools
+RUN --mount=type=cache,target=/root/.cache python -m pip install -U pip wheel pip-tools "setuptools<82.0.0"
 
 
 #################################################

tests/test_import.py

@@ -1,11 +1,12 @@
 import os
-import subprocess
+import re
+
 from importlib import import_module
 from pathlib import Path
-import re
+from importlib.metadata import distribution
+
 
 import pytest
-from pkg_resources import Requirement, get_provider
 
 
 # packages that have no way to detect their importable name
@@ -15,33 +16,42 @@
     "qtpy": None,  # required dependency of jupyter-lab
 }
 
+
 def get_module_names(pkg_name):
-    """Load pkg metadata to find out its importable module name(s)."""
+    """Load distribution to find out its importable module name(s)."""
     # remove any extras
-    pkg_name = re.sub(r'\[.*\]', '', pkg_name)
+    pkg_name = re.sub(r"\[.*\]", "", pkg_name)
     modules = set()
-    provider = get_provider(Requirement.parse(pkg_name))
     # top level package name is typically all we need
+    dist = distribution(pkg_name)
     if pkg_name in BAD_PACKAGES:
         name = BAD_PACKAGES[pkg_name]
-        if name is None:  # unimportably package
+        if name is None:  # unimportable package
             return []
         modules.add(BAD_PACKAGES[pkg_name])
-    elif provider.has_metadata("top_level.txt"):
-        first_line = list(provider.get_metadata_lines("top_level.txt"))[0]
-        modules.add(first_line)
+    elif top_level_names := dist.read_text("top_level.txt"):
+        # Find the first non-_ prefixed module
+        if first_public_name := next(
+            (
+                name
+                for name in top_level_names.strip().split("\n")
+                if not name.startswith("_")
+            ),
+            None,
+        ):
+            modules.add(first_public_name)
     else:
         # badly packaged dependency, make an educated guess
         name = pkg_name
         if pkg_name.endswith("-cffi"):
             name = pkg_name[:-5]
         elif pkg_name.endswith("-py"):
             name = pkg_name[:-3]
-        
+
         modules.add(name.replace("-", "_"))
 
-    if provider.has_metadata("namespace_packages.txt"):
-        modules |= set(provider.get_metadata_lines("namespace_packages.txt"))
+    if namespace_packages := dist.read_text("namespace_packages.txt"):
+        modules |= set(namespace_packages.strip().split("\n"))
 
     # _ prefixed modules are typically C modules and not directly importable
     return [n for n in modules if n[0] != "_"]