[EngSys] Add check ARMAutoSignoffPreview (#32457)

- Fixes #32173

.github/package.json

@@ -5,6 +5,7 @@
     "@types/github-script": "github:actions/github-script",
     "@octokit/webhooks-types": "^7.5.1",
     "@vitest/coverage-v8": "^3.0.5",
+    "memfs": "^4.17.0",
     "prettier": "^3.3.3",
     "vitest": "^3.0.5"
   },

.github/src/context.js

@@ -60,9 +60,9 @@ export async function extractInputs(github, context, core) {
       // empty for non-fork PRs.
       issue_number = pull_requests[0].number;
     } else {
-      // For fork PRs, we must call an API in the head repository to get the PR number in the target repository
+      // For fork PRs, we must call an API in the head repository to get the PR number in the base repository
 
-      // Owner and repo for the PR head (at least one should differ from target for fork PRs)
+      // Owner and repo for the PR head (at least one should differ from base for fork PRs)
       const head_owner = payload.workflow_run.head_repository.owner.login;
       const head_repo = payload.workflow_run.head_repository.name;
       const head_sha = payload.workflow_run.head_sha;

.github/src/label.js

@@ -0,0 +1,17 @@
+// @ts-check
+
+// @ts-nocheck Prevent false positive for duplicate typedef and const names
+/**
+ * @typedef {"none" | "add" | "remove"} LabelAction
+ */
+
+/**
+ * @readonly
+ * @enum {LabelAction}
+ */
+export const LabelAction = Object.freeze({
+  None: "none",
+  Add: "add",
+  Remove: "remove",
+});
+// @ts-check

.github/test/mocks.js

@@ -1,9 +1,33 @@
 import { vi } from "vitest";
 
+// Partial mock of `github` parameter passed into github-script actions
+export function createMockGithub() {
+  return {
+    rest: {
+      actions: {
+        listWorkflowRunArtifacts: vi
+          .fn()
+          .mockResolvedValue({ data: { artifacts: [] } }),
+      },
+      checks: {
+        listForRef: vi.fn().mockResolvedValue({ data: { check_runs: [] } }),
+      },
+      issues: {
+        addLabels: vi.fn(),
+        listLabelsOnIssue: vi.fn().mockRejectedValue({ data: [] }),
+        removeLabel: vi.fn(),
+      },
+    },
+  };
+}
+
 // Partial mock of `core` parameter passed into to github-script actions
 export function createMockCore() {
   return {
     debug: vi.fn(console.debug),
     info: vi.fn(console.log),
+    setOutput: vi.fn((name, value) =>
+      console.log(`setOutput('${name}', '${value}')`),
+    ),
   };
 }

.github/workflows/arm-auto-signoff-preview.yaml

@@ -0,0 +1,74 @@
+name: ARM Auto Signoff (Preview)
+
+on:
+  check_suite:
+    # Depends on check_run status, so must re-evaluate whenever a check_suite is completed.
+    # Could instead trigger on check_run events, but I think this is unnecessarily noisy.
+    types: [completed]
+  pull_request:
+    types:
+      # Depends on labels, so must re-evaluate whenever a label is manually added or removed.
+      - labeled
+      - unlabeled
+      # Depends on changed files and check_run status, so must re-evaluate whenever either could change
+      - opened
+      - reopened
+      - synchronize
+  # For manual testing
+  workflow_dispatch:
+    inputs:
+      owner:
+        description: The account owner of the repository. The name is not case sensitive.
+        required: true
+        type: string
+      repo:
+        description: The name of the repository without the .git extension. The name is not case sensitive.
+        required: true
+        type: string
+      issue_number:
+        description: The number of the pull request.
+        required: true
+        type: string
+      head_sha:
+        description: The SHA of the commit.
+        required: true
+        type: string
+
+permissions:
+  contents: read
+
+jobs:
+  arm-auto-signoff-preview:
+    name: ARM Auto Signoff (Preview)
+
+    runs-on: ubuntu-24.04
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          # Required to determine files changed in PR
+          fetch-depth: 2
+
+      # Output is "none" for no-op, "add" to add label, and "remove" to remove label
+      - id: get-label-action
+        name: ARM Auto Signoff (Preview)
+        uses: actions/github-script@v7
+        with:
+          result-encoding: string
+          script: |
+            const { default: getLabelAction } =
+              await import('${{ github.workspace }}/.github/workflows/src/arm-auto-signoff-preview.js');
+            return await getLabelAction({ github, context, core });
+        env:
+          OWNER: ${{ inputs.owner }}
+          REPO: ${{ inputs.repo }}
+          ISSUE_NUMBER: ${{ inputs.issue_number }}
+          HEAD_SHA: ${{ inputs.head_sha }}
+
+      - if: ${{ steps.get-label-action.outputs.result == 'add' || steps.get-label-action.outputs.result == 'remove' }}
+        name: Upload artifact with results
+        uses: ./.github/actions/add-label-artifact
+        with:
+          name: "ARMAutoSignoffPreview"
+          # Convert "add/remove" to "true/false"
+          value: "${{ steps.get-label-action.outputs.result == 'add' }}"