Use nix run

.github/workflows/test-dafny.yml

@@ -9,4 +9,4 @@ jobs:
       - name: Install Nix
         uses: cachix/install-nix-action@v20
       - name: Run Dafny Tests
-        run: nix shell nixpkgs#dafny -c "scripts/dafny-test-all.sh"
+        run: nix run

flake.nix

@@ -0,0 +1,22 @@
+{
+  description = "Test dafny projects";
+
+  inputs = {
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+  };
+
+  outputs = inputs@{ flake-parts, ... }:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = [ "x86_64-linux" "aarch64-linux" "aarch64-darwin" "x86_64-darwin" ];
+      perSystem = { config, self', inputs', pkgs, system, ... }: {
+        packages.default = pkgs.writeShellScriptBin "dafny-test-all" ''
+            for f in *.dfy
+            do
+                echo "Testing $f"
+                ${pkgs.dafny}/bin/dafny verify --verification-time-limit 10 $f
+            done
+        '';
+      };
+    };
+}