cli: remove old jest ESM transform

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/wise-camels-run.md

@@ -11,3 +11,5 @@ To counteract the slowdown of the additional transforms that have been introduce
 Another change that will speed up test execution is that the transformer for `.esm.js` files has been switched. It used to be an ESM transformer based on Babel, but it is also done by sucrase now since it is significantly faster.
 
 The changes above are not strictly breaking as all tests should still work. It may however cause excessive slowdowns in projects that have configured custom transforms in the `jest` field within `package.json` files. In this case it is either best to consider removing the custom transforms, or overriding the `transformIgnorePatterns` to instead use Jest's default `'/node_modules/'` pattern.
+
+This change also removes the `@backstage/cli/config/jestEsmTransform.js` transform, which can be replaced by using the `@backstage/cli/config/sucraseEsmTransform.js` transform instead.

packages/cli/config/jestEsmTransform.js

@@ -1,36 +0,0 @@
-/*
- * Copyright 2020 The Backstage Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-const babel = require('@babel/core');
-
-// We build .esm.js files with plugin:build, so to be able to load these in tests they need to be transformed
-// TODO: jest is working on module support, it's possible that we can remove this in the future
-module.exports = {
-  process(src) {
-    const result = babel.transform(src, {
-      babelrc: false,
-      compact: false,
-      plugins: [
-        // This transforms the regular ESM syntax, import and export statements
-        require.resolve('@babel/plugin-transform-modules-commonjs'),
-        // This transforms dynamic `import()`, which is not supported yet in the Node.js VM API
-        require.resolve('babel-plugin-dynamic-import-node'),
-      ],
-    });
-
-    return result.code;
-  },
-};

packages/cli/package.json

@@ -28,8 +28,6 @@
     "backstage-cli": "bin/backstage-cli"
   },
   "dependencies": {
-    "@babel/core": "^7.4.4",
-    "@babel/plugin-transform-modules-commonjs": "^7.4.4",
     "@backstage/cli-common": "^0.1.4",
     "@backstage/config": "^0.1.10",
     "@backstage/config-loader": "^0.6.10",
@@ -54,7 +52,6 @@
     "@typescript-eslint/eslint-plugin": "^v4.30.0",
     "@typescript-eslint/parser": "^v4.28.3",
     "@yarnpkg/lockfile": "^1.1.0",
-    "babel-plugin-dynamic-import-node": "^2.3.3",
     "bfj": "^7.0.2",
     "buffer": "^6.0.3",
     "chalk": "^4.0.0",

yarn.lock

@@ -375,7 +375,7 @@
     semver "^5.4.1"
     source-map "^0.5.0"
 
-"@babel/core@^7.0.0", "@babel/core@^7.1.0", "@babel/core@^7.12.10", "@babel/core@^7.12.3", "@babel/core@^7.13.16", "@babel/core@^7.4.4", "@babel/core@^7.7.5":
+"@babel/core@^7.0.0", "@babel/core@^7.1.0", "@babel/core@^7.12.10", "@babel/core@^7.12.3", "@babel/core@^7.13.16", "@babel/core@^7.7.5":
   version "7.14.8"
   resolved "https://registry.npmjs.org/@babel/core/-/core-7.14.8.tgz#20cdf7c84b5d86d83fac8710a8bc605a7ba3f010"
   integrity sha512-/AtaeEhT6ErpDhInbXmjHcUQXH0L0TEgscfcxk1qbOvLuKCa5aZT0SOOtDKFY96/CLROwbLSKyFor6idgNaU4Q==
@@ -1536,7 +1536,7 @@
     "@babel/helper-plugin-utils" "^7.14.5"
     babel-plugin-dynamic-import-node "^2.3.3"
 
-"@babel/plugin-transform-modules-commonjs@^7.0.0", "@babel/plugin-transform-modules-commonjs@^7.13.8", "@babel/plugin-transform-modules-commonjs@^7.14.0", "@babel/plugin-transform-modules-commonjs@^7.14.5", "@babel/plugin-transform-modules-commonjs@^7.4.4":
+"@babel/plugin-transform-modules-commonjs@^7.0.0", "@babel/plugin-transform-modules-commonjs@^7.13.8", "@babel/plugin-transform-modules-commonjs@^7.14.0", "@babel/plugin-transform-modules-commonjs@^7.14.5":
   version "7.14.5"
   resolved "https://registry.npmjs.org/@babel/plugin-transform-modules-commonjs/-/plugin-transform-modules-commonjs-7.14.5.tgz#7aaee0ea98283de94da98b28f8c35701429dad97"
   integrity sha512-en8GfBtgnydoao2PS+87mKyw62k02k7kJ9ltbKe0fXTHrQmG6QZZflYuGI1VVG7sVpx4E1n7KBpNlPb8m78J+A==