Verify output of invoking pkl in action test

Author: jasongwartz

.github/workflows/ci.yml

@@ -49,6 +49,7 @@ jobs:
       matrix:
         # Right now macos-13 is amd64 while macos-14 is aarch64 (M1)
         os: [ubuntu-latest, macos-13, macos-14, windows-latest]
+        pkl_version: [0.26.0, 0.26.1, 0.26.2, 0.26.3]
     runs-on: ${{ matrix.os }}
 
     steps:
@@ -60,8 +61,28 @@ jobs:
         id: test-action
         uses: ./
         with:
-          pkl-version: 0.26.0
+          pkl-version: ${{ matrix.pkl_version }}
           github-token: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Confirm download
-        run: pkl --version
+        uses: mathiasvr/command-output@v2.0.0
+        id: check-exec
+        with:
+          run: pkl --version
+
+      - name: Verify stdout
+        uses: actions/github-script@v7
+        env:
+          RESULT: ${{ steps.check-exec.outputs.stdout }}
+          PKL_VERSION: ${{ matrix.pkl_version }}
+        with:
+          script: |
+            const output = process.env.RESULT;
+            const pklVersion = process.env.PKL_VERSION;
+            const expectedStart = `Pkl ${pklVersion}`
+            console.log(`Output from executing pkl was: ${output}`)
+            if (output.startsWith(expectedStart)) {
+              console.log('Output starts with expected string:', expectedStart);
+            } else {
+              throw new Error('Output does not start with expected string:', expectedStart);
+            }