let's try this?

Author: joshuadavidthomas

.github/workflows/test.yml

@@ -25,8 +25,7 @@ jobs:
   generate-matrix:
     runs-on: ubuntu-latest
     outputs:
-      include: ${{ steps.set-version-matrix.outputs.include }}
-      os: ${{ steps.set-os-matrix.outputs.os }}
+      matrix: ${{ steps.set-matrix.outputs.include }}
     steps:
       - uses: actions/checkout@v4
 
@@ -36,25 +35,17 @@ jobs:
           enable-cache: true
           pyproject-file: pyproject.toml
 
-      - id: set-version-matrix
+      - id: set-matrix
         run: |
           uv run noxfile.py --session gha_matrix
 
-      - id: set-os-matrix
-        run: |
-          os_input="${{ inputs.os || 'ubuntu-latest' }}"
-          # -R reads raw string, split(",") creates array, map(gsub(...)) trims whitespace, -c outputs compact JSON
-          echo "os=$(echo '${{ inputs.os || 'ubuntu-latest' }}' | jq -R -c 'split(",") | map(gsub("^ *| *$"; ""))')" >> "$GITHUB_OUTPUT"
-
   test:
     name: Python ${{ matrix.python-version }}, Django ${{ matrix.django-version }} (${{ matrix.os }})
     runs-on: ${{ matrix.os }}
     needs: generate-matrix
     strategy:
       fail-fast: false
-      matrix:
-        os: ${{ fromJSON(needs.generate-matrix.outputs.os) }}
-        include: ${{ fromJSON(needs.generate-matrix.outputs.include) }}
+      matrix: ${{ fromJSON(needs.generate-matrix.outputs.matrix) }}
     steps:
       - uses: actions/checkout@v4
 

noxfile.py

@@ -124,17 +124,28 @@ def lint(session):
 
 @nox.session
 def gha_matrix(session):
+    os_args = session.posargs[0]
+    os_list = [os.strip() for os in os_args.split(",") if os_args.strip()] or [
+        "ubuntu-latest"
+    ]
+
     sessions = session.run("nox", "-l", "--json", external=True, silent=True)
-    matrix = [
+    versions_list = [
         {
             "django-version": session["call_spec"]["django"],
             "python-version": session["python"],
         }
         for session in json.loads(sessions)
         if session["name"] == "tests"
     ]
-    with Path(os.environ["GITHUB_OUTPUT"]).open("a") as fh:
-        print(f"include={matrix}", file=fh)
+
+    matrix = [{**combo, "os": os} for os in os_list for combo in versions_list]
+
+    if os.environ.get("GITHUB_OUTPUT"):
+        with Path(os.environ["GITHUB_OUTPUT"]).open("a") as fh:
+            print(f"matrix={matrix}", file=fh)
+    else:
+        print(matrix)
 
 
 if __name__ == "__main__":