Introduce experimental chart release (#4373)

.github/workflows/gha-validate-chart.yaml

@@ -18,7 +18,7 @@ on:
   workflow_dispatch:
 env:
   KUBE_SCORE_VERSION: 1.16.1
-  HELM_VERSION: v3.17.0
+  HELM_VERSION: v3.19.4
 
 permissions:
   contents: read
@@ -61,6 +61,26 @@ jobs:
           if [[ -n "$changed" ]]; then
             echo "changed=true" >> $GITHUB_OUTPUT
           fi
+          echo "changed_charts<<EOF" >> $GITHUB_OUTPUT
+          echo "$changed" >> $GITHUB_OUTPUT
+          echo "EOF" >> $GITHUB_OUTPUT
+
+      - name: Install helm-unittest
+        if: |
+          contains(steps.list-changed.outputs.changed_charts, 'charts/gha-runner-scale-set-controller-experimental') ||
+          contains(steps.list-changed.outputs.changed_charts, 'charts/gha-runner-scale-set-experimental')
+        run: |
+          helm plugin install https://github.com/helm-unittest/helm-unittest.git
+
+      - name: Run helm-unittest (gha-runner-scale-set-controller-experimental)
+        if: contains(steps.list-changed.outputs.changed_charts, 'charts/gha-runner-scale-set-controller-experimental')
+        run: |
+          helm unittest ./charts/gha-runner-scale-set-controller-experimental/
+
+      - name: Run helm-unittest (gha-runner-scale-set-experimental)
+        if: contains(steps.list-changed.outputs.changed_charts, 'charts/gha-runner-scale-set-experimental')
+        run: |
+          helm unittest ./charts/gha-runner-scale-set-experimental/
 
       - name: Run chart-testing (lint)
         run: |