feat: add @rxts/mdx/no-unused-expressions rule to replace eslint's

Author: JounQin

.eslintrc.js

@@ -28,12 +28,6 @@ module.exports = {
     {
       files: ['*.mdx'],
       extends: ['plugin:@rxts/mdx/recommended'],
-      parserOptions: {
-        parser: 'babel-eslint',
-      },
-      rules: {
-        'no-unused-expressions': 0,
-      },
     },
     {
       files: ['*.ts', '*.tsx'],

CHANGELOG.md

@@ -2,7 +2,12 @@
 
 All notable changes to this project will be documented in this file. See [standard-version](https://github.com/conventional-changelog/standard-version) for commit guidelines.
 
-### [0.4.1](https://github.com/rx-ts/eslint-plugin-mdx/compare/v0.4.0...v0.4.1) (2019-07-31)
+## [0.4.1](https://github.com/rx-ts/eslint-plugin-mdx/compare/v0.4.0...v0.4.1) (2019-07-31)
+
+
+### Features
+
+* perf: extract `parseMdx`, exports everything in package ([1f965a1](https://github.com/rx-ts/eslint-plugin-mdx/commit/1f965a1))
 
 ## [0.4.0](https://github.com/rx-ts/eslint-plugin-mdx/compare/v0.3.1...v0.4.0) (2019-07-31)
 
@@ -16,7 +21,7 @@ All notable changes to this project will be documented in this file. See [standa
 
 ### Bug Fixes
 
-* .* could not match multi lines, use [\s\S]* instead, close [#4](https://github.com/rx-ts/eslint-plugin-mdx/issues/4) ([f7e7efe](https://github.com/rx-ts/eslint-plugin-mdx/commit/f7e7efe))
+* `.*` could not match multi lines, use `[\s\S]*` instead, close [#4](https://github.com/rx-ts/eslint-plugin-mdx/issues/4) ([f7e7efe](https://github.com/rx-ts/eslint-plugin-mdx/commit/f7e7efe))
 
 ## [0.3.0](https://github.com/rx-ts/eslint-plugin-mdx/compare/v0.2.1...v0.3.0) (2019-07-30)
 
@@ -39,35 +44,27 @@ All notable changes to this project will be documented in this file. See [standa
 
 * support custom parser like babel-eslint ([b718574](https://github.com/rx-ts/eslint-plugin-mdx/commit/b718574))
 
-
-
 ### [0.1.3](https://github.com/rx-ts/eslint-plugin-mdx/compare/v0.1.2...v0.1.3) (2019-07-29)
 
 
 ### Bug Fixes
 
 * upgrade peer dependency eslint to >= 6.0.0 ([#3](https://github.com/rx-ts/eslint-plugin-mdx/issues/3) [#4](https://github.com/rx-ts/eslint-plugin-mdx/issues/4)) ([f0ab288](https://github.com/rx-ts/eslint-plugin-mdx/commit/f0ab288))
 
-
-
 ### [0.1.2](https://github.com/rx-ts/eslint-plugin-mdx/compare/v0.1.1...v0.1.2) (2019-07-29)
 
 
 ### Bug Fixes
 
 * show correct column and line on lint error ([90c5390](https://github.com/rx-ts/eslint-plugin-mdx/commit/90c5390))
 
-
-
 ### [0.1.1](https://github.com/rx-ts/eslint-plugin-mdx/compare/v0.1.0...v0.1.1) (2019-07-29)
 
 
 ### Bug Fixes
 
 * overrides in node_modules seems not working ([d2f1535](https://github.com/rx-ts/eslint-plugin-mdx/commit/d2f1535))
 
-
-
 ## 0.1.0 (2019-07-29)
 
 

README.md

@@ -57,6 +57,8 @@ npm i -D @rxts/eslint-plugin-mdx
             "parser": "@rxts/eslint-plugin-mdx",
             "plugins": ["@rxts/mdx"],
             "rules": {
+              "@rxts/mdx/no-unused-expressions": 2,
+              "no-unused-expressions": 0,
               "react/react-in-jsx-scope": 0
             }
           }
@@ -86,12 +88,9 @@ npm i -D @rxts/eslint-plugin-mdx
    }
    ```
 
-## Limitations
+## Limitation
 
-1. This parser/plugin can only handle ES syntaxes for you, markdown related syntaxes will just be ignored, you can use [markdownlint](https://github.com/markdownlint/markdownlint) to lint that part.
-
-2. `MDX` can render `jsx` block automatically without exporting them, but `eslint` will report `no-unused-expressions` issue which could be unexpected, so you may need to disable this rule for `*.mdx`.
-   I'm not going to disable this rule in the recommended config, because I'm going to add a custom `mdx/no-unused-expressions` rule to replace the incompatible one, which should not affect the `jsx` codes.
+> This parser/plugin can only handle ES syntaxes for you, markdown related syntaxes will just be ignored, you can use [markdownlint](https://github.com/markdownlint/markdownlint) to lint that part.
 
 ## Changelog
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@rxts/eslint-plugin-mdx",
-  "version": "0.4.1",
+  "version": "0.5.0",
   "description": "ESLint Parser/Plugin for MDX",
   "repository": "[email protected]:rx-ts/eslint-plugin-mdx.git",
   "author": "JounQin <[email protected]>",
@@ -16,6 +16,15 @@
     "test": "jest",
     "lint": "eslint . --ext js,mdx,ts,tsx"
   },
+  "keywords": [
+    "eslint",
+    "eslint-parser",
+    "eslint-plugin",
+    "eslint-parser-mdx",
+    "eslint-plugin-mdx",
+    "mdx",
+    "eslint-mdx"
+  ],
   "peerDependencies": {
     "eslint": ">=5.0.0"
   },

src/index.ts

@@ -3,13 +3,16 @@ import path from 'path'
 export * from './helper'
 export * from './parser'
 export * from './regexp'
+export * from './rules'
 export * from './traverse'
 
 export const configs = {
   recommended: {
     parser: path.resolve(__dirname, 'parser'),
     plugins: ['@rxts/mdx'],
     rules: {
+      '@rxts/mdx/no-unused-expressions': 2,
+      'no-unused-expressions': 0,
       'react/react-in-jsx-scope': 0,
     },
   },

src/parser.ts

@@ -27,7 +27,7 @@ export const parseMdx = unified()
 
 export const parseForESLint = (
   code: string,
-  options: Linter.ParserOptions,
+  options: Linter.ParserOptions = {},
 ): Linter.ESLintParseResult => {
   let { parser } = options
 
@@ -45,7 +45,12 @@ export const parseForESLint = (
       }
     }
   } else {
-    parser = esParse
+    try {
+      // try to load babel-eslint automatically
+      parser = require(require.resolve('babel-eslint')).parse
+    } catch (e) {
+      parser = esParse
+    }
   }
 
   const root = parseMdx(code) as Parent

src/rules/index.ts

@@ -0,0 +1,5 @@
+import { noUnUsedExpressions } from './no-unused-expressions'
+
+export const rules = {
+  'no-unused-expressions': noUnUsedExpressions,
+}

src/rules/no-unused-expressions.ts

@@ -0,0 +1,34 @@
+// eslint-disable-next-line @typescript-eslint/no-triple-slash-reference
+/// <reference path="../../types.d.ts" />
+
+import ESLintNoUnUsedExpressions from 'eslint/lib/rules/no-unused-expressions'
+
+import { Rule } from 'eslint'
+import { ExpressionStatement, Node } from 'estree'
+
+export const JSX_TYPES = ['JSXElement', 'JSXFragment'] as const
+
+export type JsxType = (typeof JSX_TYPES)[number]
+
+export interface ExpressionStatementWithParent extends ExpressionStatement {
+  parent?: {
+    type: Node['type']
+  }
+}
+
+export const noUnUsedExpressions: Rule.RuleModule = {
+  create(context) {
+    const esLintRuleListener = ESLintNoUnUsedExpressions.create(context)
+    return {
+      ExpressionStatement(node: ExpressionStatementWithParent) {
+        if (
+          JSX_TYPES.includes(node.expression.type as JsxType) &&
+          node.parent.type === 'Program'
+        ) {
+          return
+        }
+        esLintRuleListener.ExpressionStatement(node)
+      },
+    }
+  },
+}

tsconfig.json

@@ -11,6 +11,7 @@
     "outDir": "dist",
     "sourceMap": true,
     "strict": true,
+    "strictFunctionTypes": false,
     "strictNullChecks": false,
     "target": "es5"
   }

types.d.ts

@@ -4,6 +4,12 @@ declare interface SyntaxError {
   lineNumber?: number
 }
 
+declare module 'eslint/lib/rules/no-unused-expressions' {
+  import { Rule } from 'eslint'
+  const noUnUsedExpressions: Rule.RuleModule
+  export = noUnUsedExpressions
+}
+
 declare module 'espree' {
   import * as estree from 'estree'