hm, i dunno if i like this

Author: NullVoxPopuli

.github/workflows/glimmer-syntax-prettier-smoke-test.yml

@@ -0,0 +1,66 @@
+name: "@glimmer/syntax Prettier Smoke Test"
+
+on:
+  push:
+    branches:
+      - main
+      - beta
+      - release
+      - release*
+      - lts*
+    paths:
+      - 'packages/@glimmer/syntax/**'
+      - 'packages/@glimmer/interfaces/**'
+      - 'packages/@glimmer/util/**'
+      - 'packages/@glimmer/wire-format/**'
+      - 'packages/@handlebars/parser/**'
+  pull_request:
+    paths:
+      - 'packages/@glimmer/syntax/**'
+      - 'packages/@glimmer/interfaces/**'
+      - 'packages/@glimmer/util/**'
+      - 'packages/@glimmer/wire-format/**'
+      - 'packages/@handlebars/parser/**'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  prettier-smoke-test:
+    name: Prettier handlebars smoke test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - name: Setup Node.js and pnpm
+        uses: ./.github/actions/setup
+
+      - name: Build @glimmer/syntax
+        working-directory: packages/@glimmer/syntax
+        run: pnpm exec rollup -c rollup.config.mjs
+
+      - name: Pack @glimmer/syntax
+        working-directory: packages/@glimmer/syntax
+        run: pnpm pack --ignore-scripts --out ${{ github.workspace }}/glimmer-syntax.tgz
+
+      - name: Checkout prettier/prettier
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          repository: prettier/prettier
+          path: prettier-repo
+
+      - name: Enable corepack (yarn 4)
+        run: corepack enable
+
+      - name: Install prettier dependencies
+        working-directory: prettier-repo
+        run: yarn install
+
+      - name: Install local @glimmer/syntax into prettier
+        working-directory: prettier-repo
+        run: yarn add "@glimmer/syntax@file:${{ github.workspace }}/glimmer-syntax.tgz"
+
+      - name: Run prettier handlebars tests
+        working-directory: prettier-repo
+        run: yarn jest tests/format/handlebars

packages/@glimmer/syntax/rollup.config.mjs

@@ -0,0 +1,74 @@
+import { dirname, resolve } from 'node:path';
+import { existsSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import { babel } from '@rollup/plugin-babel';
+import {
+  exposedDependencies,
+  hiddenDependencies,
+  externalizePackages,
+} from '../../rollup.config.mjs';
+
+// @glimmer/syntax has known internal circular dependencies.
+function onLog(level, log, handler) {
+  if (log.code === 'CIRCULAR_DEPENDENCY') {
+    return;
+  }
+  handler(level, log);
+}
+
+// Mirrors the resolveTS() helper in the root rollup config.
+function resolveTS() {
+  return {
+    name: 'resolve-ts',
+    async resolveId(source, importer) {
+      let result = await this.resolve(source, importer);
+      if (result === null && importer) {
+        let stem = resolve(dirname(importer), source);
+        for (let candidate of ['.ts', '/index.ts']) {
+          let fullPath = stem + candidate;
+          if (existsSync(fullPath)) {
+            return fullPath;
+          }
+        }
+      }
+      return result;
+    },
+  };
+}
+
+const plugins = [
+  babel({
+    babelHelpers: 'bundled',
+    extensions: ['.js', '.ts'],
+    configFile: false,
+    plugins: [['@babel/plugin-transform-typescript', { allowDeclareFields: true }]],
+  }),
+  resolveTS(),
+  externalizePackages({ ...exposedDependencies(), ...hiddenDependencies() }),
+];
+
+const sharedOutput = {
+  hoistTransitiveImports: false,
+  generatedCode: 'es2015',
+};
+
+export default [
+  {
+    onLog,
+    input: './index.ts',
+    output: { ...sharedOutput, format: 'es', file: './dist/prod/index.js' },
+    plugins,
+  },
+  {
+    onLog,
+    input: './index.ts',
+    output: { ...sharedOutput, format: 'es', file: './dist/dev/index.js' },
+    plugins,
+  },
+  {
+    onLog,
+    input: './index.ts',
+    output: { ...sharedOutput, format: 'cjs', file: './dist/dev/index.cjs' },
+    plugins,
+  },
+];