🐛 fix(tox_env): canonicalize names when resolving dependency-group extras

docs/changelog/4061.bugfix.rst

@@ -0,0 +1,3 @@
+A ``dependency-groups`` self-reference such as ``demo_pkg[extra_1]`` now matches the project name and the
+``project.optional-dependencies`` keys after PEP 503 normalization, so a non-canonical spelling no longer fails with
+``extra not found`` nor reaches pip unresolved - by :user:`MohammedAlkindi`.

src/tox/tox_env/python/dependency_groups.py

@@ -53,9 +53,10 @@ def unwrap_nested_extras(
     if not project_name:
         return dependencies
 
+    normed_project_name = canonicalize_name(project_name)
     extras_to_unwrap: set[Requirement] = set()
     for dependency in dependencies:
-        if dependency.name == project_name:
+        if canonicalize_name(dependency.name) == normed_project_name:
             extras_to_unwrap.add(dependency)
     if not extras_to_unwrap:
         return dependencies
@@ -86,7 +87,10 @@ def resolve(root: Path, groups: set[str]) -> set[Requirement]:
         result = result.union(_resolve_dependency_group(dependency_groups, group, original_names_lookup))
 
     project_name = pyproject.get("project", {}).get("name")
-    optional_dependencies = pyproject.get("project", {}).get("optional-dependencies", {})
+    optional_dependencies: dict[str, list[str]] = {
+        canonicalize_name(name): deps
+        for name, deps in pyproject.get("project", {}).get("optional-dependencies", {}).items()
+    }
 
     return unwrap_nested_extras(optional_dependencies, project_name, result, set())
 

tests/tox_env/python/test_dependency_groups.py

@@ -0,0 +1,30 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from tox.tox_env.python.dependency_groups import resolve
+
+if TYPE_CHECKING:
+    from pathlib import Path
+
+
+def test_extra_key_not_canonical(tmp_path: Path) -> None:
+    (tmp_path / "pyproject.toml").write_text(
+        '[project]\nname = "demo-pkg"\n'
+        '[project.optional-dependencies]\nextra_1 = ["extra-pkg>=1.0"]\n'
+        '[dependency-groups]\ntest = ["demo-pkg[extra_1]"]\n',
+        encoding="utf-8",
+    )
+
+    assert sorted(str(i) for i in resolve(tmp_path, {"test"})) == ["extra-pkg>=1.0"]
+
+
+def test_project_name_not_canonical(tmp_path: Path) -> None:
+    (tmp_path / "pyproject.toml").write_text(
+        '[project]\nname = "demo-pkg"\n'
+        '[project.optional-dependencies]\nextra1 = ["extra-pkg>=1.0"]\n'
+        '[dependency-groups]\ntest = ["demo_pkg[extra1]"]\n',
+        encoding="utf-8",
+    )
+
+    assert sorted(str(i) for i in resolve(tmp_path, {"test"})) == ["extra-pkg>=1.0"]