impl conditional notification

.github/workflows/list-unhealthy-branches.yml

@@ -22,10 +22,15 @@ jobs:
     - name: List branches
       id: list-branches
       run: |
-        echo ::set-output name=SLACK_ATTACHMENTS_INACTIVE::$(node bin/github-actions/list-branches --inactive)
-        echo ::set-output name=SLACK_ATTACHMENTS_ILLEGAL::$(node bin/github-actions/list-branches --illegal)
+        export SLACK_ATTACHMENTS_ILLEGAL=`node bin/github-actions/list-branches --illegal`
+        export SLACK_ATTACHMENTS_INACTIVE=`node bin/github-actions/list-branches --inactive`
+        echo ::set-output name=SLACK_ATTACHMENTS_ILLEGAL::$SLACK_ATTACHMENTS_ILLEGAL
+        echo ::set-output name=SLACK_ATTACHMENTS_INACTIVE::$SLACK_ATTACHMENTS_INACTIVE
+        echo ::set-output name=SLACK_ATTACHMENTS_LENGTH_ILLEGAL::(echo $SLACK_ATTACHMENTS_ILLEGAL | jq '. | length')
+        echo ::set-output name=SLACK_ATTACHMENTS_LENGTH_INACTIVE::$(echo $SLACK_ATTACHMENTS_INACTIVE | jq '. | length')
 
     - name: Slack Notification for illegal named branches
+      if: steps.list-branches.outputs.SLACK_ATTACHMENTS_LENGTH_ILLEGAL > 0
       uses: tokorom/action-slack-incoming-webhook@master
       env:
         INCOMING_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL_FOR_DEV }}
@@ -34,6 +39,7 @@ jobs:
         attachments: ${{ steps.list-branches.outputs.SLACK_ATTACHMENTS_ILLEGAL }}
 
     - name: Slack Notification for inactive branches
+      if: steps.list-branches.outputs.SLACK_ATTACHMENTS_LENGTH_INACTIVE > 0
       uses: tokorom/action-slack-incoming-webhook@master
       env:
         INCOMING_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL_FOR_DEV }}