Add pull-request-test workflow

.github/workflows/pull-request-test.yml

@@ -0,0 +1,39 @@
+on:
+  pull_request:
+    branches: master
+    types: [opened, synchronize]
+
+jobs:
+  pull-request-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ./
+        with:
+          script: |
+            // Get the existing comments.
+            const {data: comments} = await github.issues.listComments({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.payload.number,
+            })
+
+            // Find any comment already made by the bot.
+            const botComment = comments.find(comment => comment.user.id === 41898282)
+            const commentBody = "Hello from actions/github-script! (${{ github.sha }})"
+
+            if (botComment) {
+              await github.issues.updateComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                comment_id: botComment.id,
+                body: commentBody
+              })
+            } else {
+              await github.issues.createComment({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: context.payload.number,
+                body: commentBody
+              })
+            }