feature: @putout/plugin-remove-useless-export-specifiers: add

Author: coderaiser

docs/syntax-errors.md

@@ -349,3 +349,15 @@ export const rules = [
 ```
 
 </details>
+
+
+<details><summary>remove useless export specifier</summary>
+
+```diff
+export const hello = () => 'world';
+export const {
+-    hello,
+}
+```
+
+</details>

packages/plugin-esm/README.md

@@ -27,6 +27,7 @@ npm i putout @putout/plugin-esm -D
 - ✅ [remove-quotes-from-import-assertions](#remove-quotes-from-import-assertions);
 - ✅ [remove-empty-import](#remove-empty-import);
 - ✅ [remove-empty-export](#remove-empty-export);
+- ✅ [remove-useless-export-specifiers](#remove-useless-export-specifiers);
 - ✅ [sort-imports-by-specifiers](#sort-imports-by-specifiers);
 - ✅ [inline-export](#inline-export);
 
@@ -54,7 +55,8 @@ npm i putout @putout/plugin-esm -D
         "esm/sort-imports-by-specifiers": "on",
         "esm/resolve-imported-file": "off",
         "esm/apply-namespace-of-file": "off",
-        "esm/inline-export": "off"
+        "esm/inline-export": "off",
+        "esm/remove-useless-export-specifiers": "off"
     }
 }
 ```
@@ -137,6 +139,20 @@ export function sum(a, b) {
 }
 ```
 
+
+### remove-useless-export-specifiers
+
+Check out in 🐊[**Putout Editor**](https://putout.cloudcmd.io/#/gist/e5c3ea469437ade0f4467323dcec9a36/7c298c7078b004ae3aba2a29e38579bf8f48a098).
+
+#### ❌ Example of incorrect code
+
+```diff
+export const hello = () => 'world';
+export const {
+-    hello,
+}
+```
+
 ### declare-imports-first
 
 Check out in 🐊[**Putout Editor**](https://putout.cloudcmd.io/#/gist/b1c18e5d726afe4ebb69d6b7a7dda82b/8189590815a1b8adb35bb8a846e28228e3c7fadf). For **CommonJS** use [nodejs/declare-after-require](https://github.com/coderaiser/putout/tree/master/packages/plugin-nodejs#declare-after-require).

packages/plugin-esm/lib/index.js

@@ -1,3 +1,4 @@
+import * as removeUselessExportSpecifiers from './remove-useless-export-specifiers/index.js';
 import * as inlineExport from './inline-export/index.js';
 import * as applyNamespaceImportToFile from './apply-namespace-import-to-file/index.js';
 import * as resolveImportedFile from './resolve-imported-file/index.js';
@@ -28,4 +29,5 @@ export const rules = {
     'apply-namespace-import-to-file': ['off', applyNamespaceImportToFile],
     'merge-declaration-with-export': mergeDeclarationWithExport,
     'inline-export': inlineExport,
+    'remove-useless-export-specifiers': removeUselessExportSpecifiers,
 };

packages/plugin-esm/lib/remove-useless-export-specifiers/fixture/apply-export-from-fix.js

@@ -0,0 +1 @@
+export * as ns from 'x';

packages/plugin-esm/lib/remove-useless-export-specifiers/fixture/apply-export-from.js

@@ -0,0 +1,3 @@
+
+import * as ns_1 from "x";
+export { ns_1 as ns };

packages/plugin-esm/lib/remove-useless-export-specifiers/fixture/remove-useless-export-specifiers-fix.js

@@ -0,0 +1,11 @@
+export {};
+
+export const hello = () => 'world';
+
+export {};
+
+const x = 3;
+
+export {
+    x,
+};

packages/plugin-esm/lib/remove-useless-export-specifiers/fixture/remove-useless-export-specifiers.js

@@ -0,0 +1,16 @@
+export {
+    z,
+}
+
+export const hello = () => 'world';
+
+export {
+    hello,
+}
+
+const x = 3;
+
+export {
+    hello,
+    x,
+}

packages/plugin-esm/lib/remove-useless-export-specifiers/index.js

@@ -0,0 +1,29 @@
+import {types, operator} from 'putout';
+
+const {remove} = operator;
+const {isExportNamedDeclaration} = types;
+
+export const report = () => `Avoid useless export specifier`;
+
+export const fix = (path) => {
+    remove(path);
+};
+
+export const traverse = ({push}) => ({
+    ExportSpecifier(path) {
+        const {node, scope} = path;
+        const {local} = node;
+        const {name} = local;
+        
+        const binding = scope.bindings[name];
+        
+        if (binding) {
+            if (isExportNamedDeclaration(binding.path.parentPath.parentPath))
+                push(path);
+            
+            return;
+        }
+        
+        push(path);
+    },
+});

packages/plugin-esm/lib/remove-useless-export-specifiers/index.spec.js

@@ -0,0 +1,26 @@
+import {createTest} from '@putout/test';
+import * as plugin from './index.js';
+import * as applyExportFrom from '../apply-export-from/index.js';
+
+const test = createTest(import.meta.url, {
+    plugins: [
+        ['remove-useless-export-specifiers', plugin],
+    ],
+});
+
+test('esm: remove-useless-export: report: remove-useless-export-specifiers', (t) => {
+    t.report('remove-useless-export-specifiers', `Avoid useless export specifier`);
+    t.end();
+});
+
+test('esm: remove-useless-export-specifiers: transform', (t) => {
+    t.transform('remove-useless-export-specifiers');
+    t.end();
+});
+
+test('esm: remove-useless-export-specifiers: transform: apply-export-from', (t) => {
+    t.transform('apply-export-from', {
+        applyExportFrom,
+    });
+    t.end();
+});

packages/plugin-esm/test/esm.js

@@ -76,3 +76,8 @@ test('plugin-esm: transform: inline-export', (t) => {
     t.transform('inline-export');
     t.end();
 });
+
+test('plugin-esm: transform: remove-useless-export-specifiers', (t) => {
+    t.transform('remove-useless-export-specifiers');
+    t.end();
+});