feat(yarn-plugin-eslint): Yarn plugin with integrated ESLint command

.changeset/spotty-cars-call.md

@@ -0,0 +1,5 @@
+---
+"@rnx-kit/yarn-plugin-eslint": minor
+---
+
+Introduce a Yarn plugin with integrated ESLint and opinionated defaults

.yarn/patches/eslint-npm-9.17.0-75805166d6.patch

@@ -0,0 +1,15 @@
+diff --git a/lib/config/config-loader.js b/lib/config/config-loader.js
+index 845cd0c92861353481d3369bb09e034e90f269ea..2eaaaade1e6b4949f1e38cee1c884f70b491b2d2 100644
+--- a/lib/config/config-loader.js
++++ b/lib/config/config-loader.js
+@@ -158,7 +158,9 @@ async function loadConfigFile(filePath, allowTS) {
+      * the require cache only if the file has been changed.
+      */
+     if (importedConfigFileModificationTime.get(filePath) !== mtime) {
+-        delete require.cache[filePath];
++        if (require.cache) {
++            delete require.cache[filePath];
++        }
+     }
+
+     const isTS = isFileTS(filePath);

incubator/yarn-plugin-eslint/README.md

@@ -0,0 +1,29 @@
+# @rnx-kit/yarn-plugin-eslint
+
+[![Build](https://github.com/microsoft/rnx-kit/actions/workflows/build.yml/badge.svg)](https://github.com/microsoft/rnx-kit/actions/workflows/build.yml)
+[![npm version](https://img.shields.io/npm/v/@rnx-kit/yarn-plugin-eslint)](https://www.npmjs.com/package/@rnx-kit/yarn-plugin-eslint)
+
+🚧🚧🚧🚧🚧🚧🚧🚧🚧🚧🚧
+
+### THIS TOOL IS EXPERIMENTAL — USE WITH CAUTION
+
+🚧🚧🚧🚧🚧🚧🚧🚧🚧🚧🚧
+
+This is a Yarn plugin that integrates ESLint and opinionated (but overridable)
+defaults, allowing you to run ESLint without having to install/configure it
+separately in every workspace.
+
+## Installation
+
+The plugin needs to be installed via `yarn plugin install` command. This needs
+to reference the produced bundle out of the `lib` folder.
+
+```sh
+yarn plugin import ./path/to/@rnx-kit/yarn-plugin-eslint/lib/index.js
+```
+
+## Usage
+
+```sh
+yarn rnx-lint
+```

incubator/yarn-plugin-eslint/package.json

@@ -0,0 +1,47 @@
+{
+  "name": "@rnx-kit/yarn-plugin-eslint",
+  "version": "0.0.1",
+  "description": "EXPERIMENTAL - USE WITH CAUTION - yarn-plugin-eslint",
+  "homepage": "https://github.com/microsoft/rnx-kit/tree/main/incubator/yarn-plugin-eslint#readme",
+  "license": "MIT",
+  "author": {
+    "name": "Microsoft Open Source",
+    "email": "[email protected]"
+  },
+  "files": [
+    "lib/index.js"
+  ],
+  "main": "lib/index.js",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/microsoft/rnx-kit",
+    "directory": "incubator/yarn-plugin-eslint"
+  },
+  "engines": {
+    "node": ">=18.19"
+  },
+  "scripts": {
+    "build": "rnx-kit-scripts build",
+    "bundle": "rnx-kit-scripts bundle --platform yarn --minify",
+    "format": "rnx-kit-scripts format"
+  },
+  "peerDependencies": {
+    "jiti": "*"
+  },
+  "peerDependenciesMeta": {
+    "jiti": {
+      "optional": true
+    }
+  },
+  "devDependencies": {
+    "@eslint/compat": "^1.2.8",
+    "@rnx-kit/eslint-plugin": "*",
+    "@rnx-kit/scripts": "*",
+    "@rnx-kit/tsconfig": "*",
+    "@yarnpkg/cli": "^4.6.0",
+    "@yarnpkg/core": "^4.0.0",
+    "clipanion": "^4.0.0-rc.4",
+    "eslint-formatter-pretty": "^6.0.1"
+  },
+  "experimental": true
+}

incubator/yarn-plugin-eslint/src/index.ts

@@ -0,0 +1,131 @@
+import { includeIgnoreFile } from "@eslint/compat";
+import { BaseCommand } from "@yarnpkg/cli";
+import { Configuration, Project } from "@yarnpkg/core";
+import { Option } from "clipanion";
+import type { Linter } from "eslint";
+import { ESLint } from "eslint";
+import { spawnSync } from "node:child_process";
+import * as fs from "node:fs";
+import * as path from "node:path";
+
+type LinterConfigs = Linter.Config<Linter.RulesRecord>[];
+
+export class Lint extends BaseCommand {
+  static override paths = [["rnx-lint"]];
+
+  fix = Option.Boolean("--fix", false, {
+    description: "Automatically fix problems",
+  });
+
+  patterns = Option.Rest({ name: "file.js" });
+
+  async execute(): Promise<number | void> {
+    const cwd = this.context.cwd;
+    const configuration = await Configuration.find(cwd, this.context.plugins);
+    const { project } = await Project.find(configuration, cwd);
+
+    const [overrideConfigFile, overrideConfig] = await this.loadConfig(cwd);
+
+    const eslint = new ESLint({
+      cwd,
+      ignorePatterns: this.ignorePatterns(project),
+      warnIgnored: false,
+      overrideConfigFile,
+      overrideConfig,
+      fix: this.fix,
+    });
+
+    const results = await eslint.lintFiles(this.filePatterns());
+    await ESLint.outputFixes(results);
+
+    const formatter = await this.loadFormatter();
+    const output = formatter.format(results);
+
+    if (output) {
+      if (ESLint.getErrorResults(results).length > 0) {
+        console.error(output);
+        return 1;
+      }
+
+      console.log(output);
+    }
+
+    return 0;
+  }
+
+  private filePatterns() {
+    if (this.patterns.length > 0) {
+      return this.patterns;
+    }
+
+    const args = [
+      "ls-files",
+      "*.cjs",
+      "*.js",
+      "*.jsx",
+      "*.mjs",
+      "*.ts",
+      "*.tsx",
+    ];
+    const { stdout } = spawnSync("git", args);
+    return stdout.toString().trim().split("\n");
+  }
+
+  private ignorePatterns(project: Project): string[] {
+    const patterns: string[] = [];
+
+    const locations = [project.cwd, this.context.cwd];
+    for (const location of locations) {
+      const gitignore = path.join(location, ".gitignore");
+      if (fs.existsSync(gitignore)) {
+        const { ignores } = includeIgnoreFile(gitignore);
+        if (ignores) {
+          patterns.push(...ignores);
+        }
+      }
+    }
+
+    return patterns;
+  }
+
+  private async loadConfig(
+    cwd: string
+  ): Promise<[boolean | string, LinterConfigs | undefined]> {
+    const eslintConfigPath = path.join(cwd, "eslint.config.js");
+    const overrideConfigFile = fs.existsSync(eslintConfigPath)
+      ? eslintConfigPath
+      : true;
+
+    if (overrideConfigFile !== true) {
+      return [eslintConfigPath, undefined];
+    }
+
+    const rnx = await import("@rnx-kit/eslint-plugin");
+    const config = [
+      ...rnx.configs.strict,
+      ...rnx.configs.stylistic,
+      {
+        rules: {
+          "@typescript-eslint/consistent-type-definitions": ["error", "type"],
+        },
+      },
+    ];
+
+    return [true, config];
+  }
+
+  /**
+   * ESLint will try to dynamically import a formatter and fail. We bundle our
+   * own formatter to bypass this.
+   */
+  private async loadFormatter() {
+    const { default: format } = await import("eslint-formatter-pretty");
+    return { format };
+  }
+}
+
+// eslint-disable-next-line no-restricted-exports
+export default {
+  name: "@rnx-kit/yarn-plugin-eslint",
+  commands: [Lint],
+};

incubator/yarn-plugin-eslint/tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "extends": "@rnx-kit/tsconfig/tsconfig.json",
+  "compilerOptions": {
+    "target": "ES2021",
+    "noEmit": true
+  },
+  "include": ["src"]
+}

package.json

@@ -62,6 +62,7 @@
     "@react-native-community/cli-types": "^15.0.0",
     "@rnx-kit/react-native-host": "workspace:*",
     "@vue/compiler-sfc": "link:./incubator/ignore",
+    "eslint": "patch:eslint@npm%3A9.17.0#~/.yarn/patches/eslint-npm-9.17.0-75805166d6.patch",
     "react-native-macos/@react-native/assets-registry": "^0.76.0",
     "react-native-macos/@react-native/codegen": "^0.76.0",
     "react-native-macos/@react-native/community-cli-plugin": "^0.76.0",

packages/eslint-plugin/package.json

@@ -53,6 +53,7 @@
     "eslint": ">=8.57.0"
   },
   "devDependencies": {
+    "@eslint/js": "^9.0.0",
     "@microsoft/eslint-plugin-sdl": "^1.0.0",
     "@rnx-kit/scripts": "*",
     "@rnx-kit/tsconfig": "*",

packages/eslint-plugin/src/rules/no-export-all.js

@@ -3,7 +3,7 @@
 
 /**
  * @typedef {import("@typescript-eslint/types/dist/index").TSESTree.Node} Node
- * @typedef {import("eslint").Linter.FlatConfig} FlatConfig
+ * @typedef {import("eslint").Linter.Config} Config
  * @typedef {import("eslint").Rule.RuleContext} ESLintRuleContext
  * @typedef {import("eslint").Rule.ReportFixer} ESLintReportFixer
  * @typedef {{ exports: string[], types: string[] }} NamedExports
@@ -16,7 +16,7 @@
  *     maxDepth: number;
  *   };
  *   filename: string;
- *   languageOptions: FlatConfig["languageOptions"];
+ *   languageOptions: Config["languageOptions"];
  *   parserOptions: ESLintRuleContext["parserOptions"];
  *   parserPath: ESLintRuleContext["parserPath"];
  *   sourceCode: ESLintRuleContext["sourceCode"];

test-repos/rnx-kit-workspaces.json

@@ -48,6 +48,7 @@
       "@rnx-kit/tsconfig": "packages/tsconfig",
       "@rnx-kit/typescript-service": "packages/typescript-service",
       "@rnx-kit/yarn-plugin-dynamic-extensions": "incubator/yarn-plugin-dynamic-extensions",
+      "@rnx-kit/yarn-plugin-eslint": "incubator/yarn-plugin-eslint",
       "@rnx-kit/yarn-plugin-external-workspaces": "incubator/yarn-plugin-external-workspaces"
     }
   }