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/src/rules/noRelativeImportsAcrossPackages.ts

@@ -0,0 +1,110 @@
+/**
+ * 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,
+              },
+            });
+          }
+        }
+      },
+    };
+  },
+});