Add printing of the lockfile after installation

Closes #783

.github/workflows/test.yml

@@ -240,6 +240,18 @@ jobs:
           ruby-version: '2.6'
       - run: ruby -v
 
+  testNoGemfileWithBundlerCache:
+    name: "Test with no Gemfile but with bundler-cache"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: rm Gemfile
+      - uses: ./
+        with:
+          ruby-version: '2.6'
+          bundler-cache: true
+      - run: ruby -v
+
   testLatestRubygemsVersion:
     name: "Test rubygems: latest on ${{ matrix.ruby }}"
     runs-on: ubuntu-latest