Add a GitHub test workflow

.github/workflows/test.yml

@@ -0,0 +1,48 @@
+on: push
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: cachix/install-nix-action@v18
+        with:
+          nix_path: nixpkgs=channel:nixos-unstable
+          extra_nix_config: |
+            access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
+      - uses: purcell/setup-emacs@master
+        with:
+          version: 27.2
+      - run: |
+          cat << 'EOF' > script.sh
+          #!/usr/bin/env bash
+          mkdir -p $(jupyter --runtime-dir)
+          jupyter --paths
+          jupyter --version
+          jupyter kernelspec list
+
+          make dev
+          make compile
+          make test
+          EOF
+
+          cat << EOF > shell.nix
+          { pkgs ? import <nixpkgs> {} }:
+          let
+            pypkgs = p: with p; [
+              jupyter-core
+              jupyter-client
+              ipykernel
+              notebook
+            ];
+          in pkgs.mkShell {
+            packages = [
+              pkgs.pandoc
+              (pkgs.python3.withPackages pypkgs)
+            ];
+          }
+          EOF
+
+          git clone https://github.com/cask/cask ~/.cask
+          export PATH=$HOME/.cask/bin:$PATH
+          chmod +x script.sh
+          nix-shell --run ./script.sh