use nox to generate github job matrix for tests (#133)

Author: joshuadavidthomas

.github/workflows/test.yml

@@ -34,7 +34,7 @@ jobs:
 
       - id: set-matrix
         run: |
-          echo "matrix=$(python -m nox -l --json | jq -c '[.[] | select(.name == "tests") | {"python-version": .python, "django-version": .call_spec.django}] | {include: .}')" >> $GITHUB_OUTPUT
+          python -m nox --session "gha_matrix"
 
   test:
     name: Python ${{ matrix.python-version }}, Django ${{ matrix.django-version }}

noxfile.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import json
 import os
 from pathlib import Path
 
@@ -130,3 +131,20 @@ def demo(session):
 
     session.install("django-simple-nav[dev] @ .")
     session.run("python", "example/demo.py", "runserver", addrport)
+
+
+@nox.session
+def gha_matrix(session):
+    sessions = session.run("nox", "-l", "--json", silent=True)
+    matrix = {
+        "include": [
+            {
+                "python-version": session["python"],
+                "django-version": session["call_spec"]["django"],
+            }
+            for session in json.loads(sessions)
+            if session["name"] == "tests"
+        ]
+    }
+    with Path(os.environ["GITHUB_OUTPUT"]).open("a") as fh:
+        print(f"matrix={matrix}", file=fh)