Use ubuntu

.github/workflows/test-dafny.yml

@@ -3,12 +3,10 @@ name: Test All Dafny Files
 on: [push]
 jobs:
   test:
-    runs-on: nixery.dev/shell/dafny
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v4
-      - name: Test All Dafny Files
-        run: |
-          for file in $(find . -name '*.dfy'); do
-            echo "Testing $file"
-            $DAFNY_HOME/dafny /compile:0 /noVerify /timeLimit:30 /vcsCores:1 /compileTarget:cs "$file"
-          done
+      - name: Install Nix
+        uses: cachix/install-nix-action@v20
+      - name: Run Dafny Tests
+        run: nix shell nixpkgs#dafny -c "scripts/dafny-test-all.sh"

scripts/dafny-test-all.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+# This script runs all dafny tests in the current directory.
+
+for f in *.dfy
+do
+    echo "Testing $f"
+    dafny verify --verification-time-limit 10 $f
+done