packages: add initial codemods package

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

packages/codemods/.eslintrc.js

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+module.exports = {
+  extends: [require.resolve('@backstage/cli/config/eslint.backend')],
+  rules: {
+    'no-console': 0,
+    'import/no-extraneous-dependencies': [
+      'error',
+      {
+        devDependencies: true,
+        optionalDependencies: false,
+        peerDependencies: false,
+        bundledDependencies: false,
+      },
+    ],
+  },
+};

packages/codemods/README.md

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+# e2e-test
+
+End-to-end test for verifying Backstage packages.
+
+## Usage
+
+This package is only meant for usage within the Backstage monorepo.
+
+All packages need to be installed and built before running the test. In a fresh clone of this repo you first need to run the following from the repo root:
+
+```sh
+yarn install
+yarn tsc
+yarn build
+```
+
+Once those tasks have completed, you can now run the test using `yarn e2e-test run`.
+
+If you make changes to other packages you will need to rerun `yarn tsc && yarn build`. Changes to this package do not require a rebuild.
+
+## Documentation
+
+- [Backstage Readme](https://github.com/backstage/backstage/blob/master/README.md)
+- [Backstage Documentation](https://github.com/backstage/backstage/blob/master/docs/README.md)

packages/codemods/bin/backstage-codemods

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+#!/usr/bin/env node
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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 path = require('path');
+
+require('ts-node').register({
+  transpileOnly: true,
+  /* eslint-disable-next-line no-restricted-syntax */
+  project: path.resolve(__dirname, '../../../tsconfig.json'),
+  compilerOptions: {
+    module: 'CommonJS',
+  },
+});
+
+require('../src');

packages/codemods/package.json

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+{
+  "name": "@backstage/codemods",
+  "description": "A collection of codemods for Backstage projects",
+  "version": "0.1.0",
+  "private": true,
+  "homepage": "https://backstage.io",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/backstage/backstage",
+    "directory": "packages/codemods"
+  },
+  "keywords": [
+    "backstage"
+  ],
+  "license": "Apache-2.0",
+  "main": "src/index.ts",
+  "scripts": {
+    "start": "nodemon --",
+    "lint": "backstage-cli lint",
+    "test": "backstage-cli test",
+    "test:e2e": "yarn start"
+  },
+  "bin": {
+    "backstage-codemods": "bin/backstage-codemods"
+  },
+  "dependencies": {
+    "chalk": "^4.0.0",
+    "jscodeshift": "^0.12.0"
+  },
+  "devDependencies": {
+    "@types/node": "^14.14.32",
+    "commander": "^6.1.0",
+    "ts-node": "^9.1.1"
+  },
+  "nodemonConfig": {
+    "watch": "./src",
+    "exec": "bin/e2e-test",
+    "ext": "ts"
+  }
+}

packages/codemods/src/index.ts

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+/*
+ * Copyright 2020 Spotify AB
+ *
+ * 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.
+ */
+
+import program, { Command } from 'commander';
+import chalk from 'chalk';
+import { version } from '../package.json';
+
+const codemods = [
+  {
+    name: 'core-imports',
+    description:
+      'Updates @backstage/core imports to use @backstage/core-* imports instead.',
+  },
+];
+
+function createCodemodAction(name: string) {
+  return (cmd: Command) => {
+    console.log(`Fake codemod ${cmd} ${name}`);
+  };
+}
+
+async function main(argv: string[]) {
+  program.name('backstage-codemods').version(version);
+
+  for (const codemod of codemods) {
+    program
+      .command(codemod.name)
+      .description(codemod.description)
+      .option('-d, --dry', 'Dry run, no changes written to files')
+      .action(createCodemodAction(codemod.name));
+  }
+
+  program.on('command:*', () => {
+    console.log();
+    console.log(chalk.red(`Invalid command: ${program.args.join(' ')}`));
+    console.log();
+    program.outputHelp();
+    process.exit(1);
+  });
+
+  program.parse(argv);
+}
+
+function exitWithError(err: Error & { code?: unknown }) {
+  process.stdout.write(`${err.name}: ${err.stack || err.message}\n`);
+
+  if (typeof err.code === 'number') {
+    process.exit(err.code);
+  } else {
+    process.exit(1);
+  }
+}
+
+process.on('unhandledRejection', (rejection: unknown) => {
+  if (rejection instanceof Error) {
+    exitWithError(rejection);
+  } else {
+    exitWithError(new Error(`Unknown rejection: '${rejection}'`));
+  }
+});
+
+main(process.argv).catch(exitWithError);