Migrate to Node 20, clean up workflows (MithrilJS#2902)

Tests still appear to fail per MithrilJS#2898. Unfortunately, I need actions/runner#2347 to ignore the test failures properly - I need them to be warnings, not hard errors.

.github/actions/setup/action.yml

@@ -0,0 +1,21 @@
+# In the future, I'd like to fold this into its own action under the Mithril.js
+# org and include `actions/checkout` as well. It'd simplify maintenance a bit
+# and I could reuse it across multiple repos.
+name: Setup CI context
+description: Sets up repo and Node context and installs packages
+
+inputs:
+  # See supported Node.js release schedule here:
+  # https://github.com/nodejs/Release
+  node-version:
+    default: 20
+    description: The Node version to use
+
+runs:
+  using: composite
+  steps:
+    - uses: actions/setup-node@v4
+      with:
+        node-version: ${{ inputs.node-version }}
+    - run: npm ci
+      shell: bash

.github/workflows/merge.yml

@@ -10,25 +10,11 @@ concurrency: prr:deploy
 
 jobs:
   merge:
-
     runs-on: ubuntu-latest
 
-    strategy:
-      matrix:
-        node-version: [16.x]
-
     steps:
-    - uses: actions/checkout@v3
-      with:
-        ref: 'next'
-        fetch-depth: 0
-
-    - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v3
-      with:
-        node-version: ${{ matrix.node-version }}
-        cache: 'npm'
-    - run: npm ci
+    - run: git clone --depth=0 https://github.com/MithrilJS/mithril.js.git && cd mithril.js
+    - uses: ./.github/actions/setup
     - run: npm run build
     - run: npx pr-release merge --target master --source next --commit --force --clean --changelog ./docs/recent-changes.md --compact --minimize-semver-change
       env:

.github/workflows/push-master.yml

@@ -1,19 +1,17 @@
-name: 'Push `master`'
+name: Warn on pushing to `master`
 on:
   pull_request:
     types: [opened]
-    branches: ['master']
+    branches: [master]
+permissions:
+  issues: write
 jobs:
   comment:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/github-script@v3
-        with:
-          github-token: ${{secrets.GITHUB_TOKEN}}
-          script: |
-            await github.issues.createComment({
-              issue_number: context.issue.number,
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              body: `⚠⚠⚠ Hey @${context.actor}, did you mean to open this against \`next\`? ⚠⚠⚠`
-            })
+      - run: |
+          gh issue comment ${{ github.event.pull_request.url }} \
+            --body '⚠⚠⚠ Hey @${{ github.actor }}, did you mean to open this against `next`? ⚠⚠⚠'
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        name: Post alert comment

.github/workflows/rollback.yml

@@ -7,24 +7,11 @@ concurrency: prr:deploy
 
 jobs:
   pr:
-
     runs-on: ubuntu-latest
 
-    strategy:
-      matrix:
-        node-version: [16.x]
-
     steps:
-    - uses: actions/checkout@v3
-      with:
-        ref: 'next'
-        fetch-depth: 0
-    - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v3
-      with:
-        node-version: ${{ matrix.node-version }}
-        cache: 'npm'
-    - run: npm ci
+    - run: git clone --depth=0 https://github.com/MithrilJS/mithril.js.git && cd mithril.js
+    - uses: ./.github/actions/setup
     - run: npm run build
     - run: npx pr-release rollback --verbose --target master --source next --verbose --ignore 'package*' --ignore docs/changelog.md --ignore docs/recent-changes.md
       env:

.github/workflows/pr.yml → .github/workflows/test-next-push.yml

@@ -1,30 +1,22 @@
-name: pr
+name: test-next-push
 
 on:
   push:
     branches: [ next ]
-
   workflow_dispatch:
 
 concurrency: prr:pre-release
 
 jobs:
-  pr:
+  build:
+    uses: ./.github/workflows/test.yml
 
+  publish-prerelease:
+    needs: build
     runs-on: ubuntu-latest
-
-    strategy:
-      matrix:
-        node-version: [16.x]
-
     steps:
-    - uses: actions/checkout@v3
-    - name: Use Node.js ${{ matrix.node-version }}
-      uses: actions/setup-node@v3
-      with:
-        node-version: ${{ matrix.node-version }}
-        cache: 'npm'
-    - run: npm ci
+    - run: git clone --depth=0 https://github.com/MithrilJS/mithril.js.git && cd mithril.js
+    - uses: ./.github/actions/setup
     - run: npm run build
     - run: npx pr-release pr --verbose --target master --source next --compact --verbose --minimize-semver-change
       env:

.github/workflows/test.yml

@@ -0,0 +1,59 @@
+name: test
+
+on:
+  pull_request:
+    branches: [ next ]
+  workflow_dispatch:
+  workflow_call:
+
+permissions:
+  actions: write
+  contents: read
+
+# This uses actions/checkout instead of `git clone` directly since it's way
+# easier than parsing everything out.
+
+jobs:
+  lint-docs:
+    # https://github.com/MithrilJS/mithril.js/issues/2898
+    # Semantics aren't quite what I'd prefer. This is what I'd really want:
+    # https://github.com/actions/runner/issues/2347#issue-comment-box
+    continue-on-error: true
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: ./.github/actions/setup
+    - run: npm run lint:docs
+
+  lint-js:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: ./.github/actions/setup
+    - run: npm run lint:js
+
+  build-js:
+    needs: lint-js
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - uses: ./.github/actions/setup
+    - run: npm run build
+
+  test-js:
+    needs: build-js
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
+        node-version:
+        - 16
+        - 18
+        - 20
+        - 22
+    steps:
+    - uses: actions/checkout@v4
+    - uses: ./.github/actions/setup
+      with:
+        node-version: ${{ matrix.node-version }}
+    - run: npm run test:js