Custom eslint rule for disallowing cross-package references

Summary:
Added infra for writing and using custom eslint rules and created a rule for disallowing cross-package file imports. Such imports are anti-pattern and they also break standalone plugin bundling.

We still have a bunch of places where Flipper core references code directly from plugins. I've ignored these places for now and added task T71355623 to revisit them.

Reviewed By: passy

Differential Revision: D22998955

fbshipit-source-id: d04cff8fc115ba1300a7e6830306ec134046e927

desktop/eslint-plugin-flipper/LICENSE

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+MIT License
+
+Copyright (c) Facebook, Inc. and its affiliates.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

desktop/eslint-plugin-flipper/jestconfig.json

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+{
+  "transform": {
+    "^.+\\.tsx?$": "ts-jest"
+  },
+  "testRegex": "(/__tests__/.*|(\\.|/)(test|spec))\\.(jsx?|tsx?)$",
+  "testPathIgnorePatterns": ["/node_modules/", "/lib/"],
+  "moduleFileExtensions": ["ts", "tsx", "js", "jsx", "json", "node"]
+}

desktop/eslint-plugin-flipper/package.json

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+{
+  "name": "eslint-plugin-flipper",
+  "version": "0.52.1",
+  "private": true,
+  "description": "Custom ESLint rules for Flipper",
+  "repository": "facebook/flipper",
+  "main": "lib/index.js",
+  "flipperBundlerEntry": "src",
+  "types": "lib/index.d.ts",
+  "license": "MIT",
+  "bugs": "https://github.com/facebook/flipper/issues",
+  "dependencies": {
+    "@typescript-eslint/experimental-utils": "^3.8.0",
+    "fs-extra": "^9.0.1"
+  },
+  "devDependencies": {
+    "@types/jest": "26",
+    "@typescript-eslint/parser": "^3.8.0",
+    "flipper-test-utils": "0.52.1",
+    "jest": "^26",
+    "metro-memory-fs": "^0.61.0",
+    "prettier": "^2.0.0",
+    "rimraf": "^3.0.2",
+    "ts-jest": "^26.0.0",
+    "ts-node": "^8",
+    "typescript": "^3.9.5"
+  },
+  "scripts": {
+    "reset": "rimraf lib *.tsbuildinfo",
+    "build": "tsc -b",
+    "prepack": "yarn reset && yarn build"
+  },
+  "files": [
+    "lib/**/*",
+    "src/**/*"
+  ],
+  "homepage": "https://github.com/facebook/flipper",
+  "keywords": [
+    "Flipper"
+  ],
+  "author": "Facebook, Inc"
+}

desktop/eslint-plugin-flipper/src/index.ts

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+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import noRelativeImportsAcrossPackages, {
+  RULE_NAME as noRelativeImportsAcrossPackagesRuleName,
+} from './rules/noRelativeImportsAcrossPackages';
+
+module.exports = {
+  rules: {
+    [noRelativeImportsAcrossPackagesRuleName]: noRelativeImportsAcrossPackages,
+  },
+};

desktop/eslint-plugin-flipper/src/rules/__tests__/noRelativeImportsAcrossPackages.node.ts

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+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {TSESLint} from '@typescript-eslint/experimental-utils';
+import rule, {RULE_NAME} from '../noRelativeImportsAcrossPackages';
+
+const tester = new TSESLint.RuleTester({
+  parser: require.resolve('@typescript-eslint/parser'),
+  parserOptions: {
+    sourceType: 'module',
+    ecmaVersion: 2020,
+  },
+});
+
+tester.run(RULE_NAME, rule, {
+  valid: [
+    {
+      code: `import * as testUtils from 'flipper-test-utils';`,
+      filename: __filename,
+    },
+    {
+      code: `const testUtils = require('flipper-test-utils');`,
+      filename: __filename,
+    },
+    {
+      code: `import rule, {RULE_NAME} from '../noRelativeImportsAcrossPackages';`,
+      filename: __filename,
+    },
+    {
+      code: `require('../noRelativeImportsAcrossPackages');`,
+      filename: __filename,
+    },
+    {
+      code: `import m from './subdir/module';`,
+      filename: __filename,
+    },
+  ],
+  invalid: [
+    {
+      code: `import * as pathUtils from '../../../../test-utils/src/pathUtils';`,
+      filename: __filename,
+      errors: [{messageId: 'noRelativeImportsAcrossPackages'}],
+    },
+    {
+      code: `require('../../../../test-utils/src/pathUtils');`,
+      filename: __filename,
+      errors: [{messageId: 'noRelativeImportsAcrossPackages'}],
+    },
+  ],
+});

desktop/eslint-plugin-flipper/src/rules/noRelativeImportsAcrossPackages.ts

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+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {resolve, dirname, join} from 'path';
+import fs from 'fs-extra';
+import {TSESTree} from '@typescript-eslint/experimental-utils';
+import {createESLintRule} from '../utils/createEslintRule';
+
+const rootDirs = new Map<string, string>();
+function findRootDir(path: string): string {
+  const cachedRoot = rootDirs.get(path);
+  if (cachedRoot) {
+    return cachedRoot;
+  }
+  if (fs.pathExistsSync(join(path, 'package.json'))) {
+    rootDirs.set(path, path);
+    return path;
+  }
+  const parentRoot = findRootDir(dirname(path));
+  rootDirs.set(path, parentRoot);
+  return parentRoot;
+}
+
+type Options = [];
+
+export type MessageIds = 'noRelativeImportsAcrossPackages';
+export const RULE_NAME = 'no-relative-imports-across-packages';
+
+export default createESLintRule<Options, MessageIds>({
+  name: RULE_NAME,
+  meta: {
+    type: 'problem',
+    docs: {
+      description: `Ensure that package boundaries are respected within monorepo`,
+      category: 'Possible Errors',
+      recommended: 'error',
+    },
+    schema: [],
+    messages: {
+      noRelativeImportsAcrossPackages: `Attempted to require "{{requiredPath}}" from file "{{filename}}" resolved to "{{resolvedPath}}" which is outside the package root dir "{{root}}".`,
+    },
+  },
+  defaultOptions: [],
+  create(context) {
+    const filename = context.getFilename();
+    const dir = dirname(filename);
+    const root = findRootDir(dir);
+    return {
+      ImportDeclaration(node: TSESTree.ImportDeclaration) {
+        if (typeof node.source.value === 'string') {
+          const requiredPath = node.source.value;
+          const resolvedPath = resolve(dir, requiredPath);
+          if (
+            // imported a file not a package
+            requiredPath.startsWith('.') &&
+            // the resolved path for the imported file is outside the package root
+            !resolvedPath.startsWith(root)
+          ) {
+            context.report({
+              node,
+              messageId: 'noRelativeImportsAcrossPackages',
+              data: {
+                filename,
+                root,
+                requiredPath,
+                resolvedPath,
+              },
+            });
+          }
+        }
+      },
+      CallExpression(node: TSESTree.CallExpression) {
+        const args = node.arguments || [];
+        if (
+          node.callee.type === 'Identifier' &&
+          node.callee.name === 'require' &&
+          args.length === 1 &&
+          args[0].type === 'Literal' &&
+          typeof args[0].value === 'string'
+        ) {
+          const requiredPath = args[0].value;
+          const resolvedPath = resolve(dir, requiredPath);
+          if (
+            // required a file not a package
+            requiredPath.startsWith('.') &&
+            // the resolved path for the required file is outside the package root
+            !resolvedPath.startsWith(root)
+          ) {
+            context.report({
+              node,
+              messageId: 'noRelativeImportsAcrossPackages',
+              data: {
+                filename,
+                root,
+                requiredPath,
+                resolvedPath,
+              },
+            });
+          }
+        }
+      },
+    };
+  },
+});

desktop/eslint-plugin-flipper/src/utils/createEslintRule.ts

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+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {ESLintUtils} from '@typescript-eslint/experimental-utils';
+
+export const createESLintRule = ESLintUtils.RuleCreator(() => ``);

desktop/eslint-plugin-flipper/tsconfig.json

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+{
+  "extends": "../tsconfig.base.json",
+  "compilerOptions": {
+    "outDir": "lib",
+    "rootDir": "src"
+  },
+  "include": ["src"],
+  "exclude": ["node_modules", "**/__tests__/*"]
+}

desktop/eslint-plugin-flipper/tslint.json

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+{
+  "extends": ["tslint:recommended", "tslint-config-prettier"],
+  "rules": {
+    "interface-name": false,
+    "variable-name": false
+  }
+}