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Add exports-last rule
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‎README.md‎

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| Rule ID | Description | |
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|:--------|:------------|:--:|
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| [@croutonn/exports-last](./docs/rules/exports-last.md) | This rule enforces that all exports are declared at the bottom of the file. This rule will report any export declarations that comes before any non-export statements. | ⭐️✒️ |
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| [@croutonn/group-exports](./docs/rules/group-exports.md) | Reports when named exports are not grouped together in a single export declaration or when multiple assignments to CommonJS module.exports or exports object are present in a single file | ⭐️✒️ |
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| [@croutonn/jsx-a11y-anchor-has-content](./docs/rules/jsx-a11y-anchor-has-content.md) | Enforce that anchors have content and that the content is accessible to screen readers | |
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| [@croutonn/jsx-a11y-control-has-associated-label](./docs/rules/jsx-a11y-control-has-associated-label.md) | Enforce that a control (an interactive element) has a text label | |

‎docs/rules/exports-last.md‎

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# @croutonn/exports-last
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> This rule enforces that all exports are declared at the bottom of the file. This rule will report any export declarations that comes before any non-export statements.
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> - ⭐️ This rule is included in `plugin:@croutonn/recommended` preset.
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> - ✒️ The `--fix` option on the [command line](https://eslint.org/docs/user-guide/command-line-interface#fixing-problems) can automatically fix some of the problems reported by this rule.
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## Rule Details
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## This will be reported
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```JS
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const bool = true
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export default bool
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const str = 'foo'
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```
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```JS
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export const bool = true
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const str = 'foo'
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```
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## This will not be reported
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```JS
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const arr = ['bar']
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export const bool = true
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export default bool
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export function func() {
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console.log('Hello World 🌍')
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}
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export const str = 'foo'
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```
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## Options
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No options
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## When Not To Use It
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If you don't mind exports being sprinkled throughout a file, you may not want to enable this rule.
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#### ES6 exports only
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The exports-last rule is currently only working on ES6 exports. You may not want to enable this rule if you're using CommonJS exports.
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If you need CommonJS support feel free to open an issue or create a PR.
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## Implementation
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- [Rule source](../../lib/rules/exports-last.js)
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- [Test source](../../tests/lib/rules/exports-last.js)

‎lib/configs/recommended.js‎

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"react/prop-types": "off",
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"@croutonn/func-style": ["error", "arrow"],
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"@croutonn/group-exports": ["error"],
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"@croutonn/exports-last": ["error"],
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"@croutonn/typescript-react-component-type": ["error", "raw"],
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"@croutonn/typescript-react-require-props-suffix": ["error"],
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"@croutonn/typescript-react-require-props-type": ["error"]

‎lib/index.js‎

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recommended: require("./configs/recommended")
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},
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rules: {
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"exports-last": require("./rules/exports-last"),
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"func-style": require("./rules/func-style"),
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"group-exports": require("./rules/group-exports"),
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"jsx-a11y-anchor-has-content": require("./rules/jsx-a11y-anchor-has-content"),

‎lib/rules/exports-last.js‎

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"use strict";
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/**
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* @typedef {import("eslint").Rule.RuleModule} RuleModule
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* @typedef {import("estree").Node} ASTNode
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* @typedef {import("eslint").Rule.RuleFixer} RuleFixer
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* @typedef {import("eslint").Rule.RuleFix} RuleFix
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*/
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const errors = {
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error: "Export statements should appear at the end of the file"
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};
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/**
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* @param {{type: string}} options
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* @returns {boolean}
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*/
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function isNonExportStatement({ type }) {
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return type !== "ExportDefaultDeclaration" &&
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type !== "ExportNamedDeclaration" &&
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type !== "ExportAllDeclaration";
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}
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/**
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* @type RuleModule
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*/
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module.exports = {
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meta: {
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docs: {
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description: "This rule enforces that all exports are declared at the bottom of the file. This rule will report any export declarations that comes before any non-export statements.",
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category: "Best Practices",
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recommended: true,
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url: "https://github.com/croutonn/eslint-plugin/blob/main/docs/rules/exports-last.md"
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},
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fixable: "code",
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messages: errors,
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schema: [],
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type: "suggestion"
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},
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create(context) {
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const sourceCode = context.getSourceCode();
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return {
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Program({ body }) {
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const lastNonExportStatementIndex = body.reduce((acc, item, index) => {
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if (isNonExportStatement(item)) {
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return index;
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}
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return acc;
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}, -1);
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if (lastNonExportStatementIndex === -1) {
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return;
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}
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const newCode = body.slice(0, lastNonExportStatementIndex + 1).map(node => ({
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node,
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code: sourceCode.getText(node),
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isNonExportStatement: isNonExportStatement(node)
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})).sort((a, b) => {
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if (!a.isNonExportStatement && b.isNonExportStatement) {
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return 1;
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}
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if (a.isNonExportStatement === b.isNonExportStatement) {
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return 0;
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}
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return -1;
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}).map(node => node.code).join("\n");
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const start = body[0].range[0];
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const end = body.slice(0, lastNonExportStatementIndex + 1).slice(-1)[0].range[1];
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let fixed = false;
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/**
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* @param {RuleFixer} fixer
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* @returns {RuleFix}
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*/
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function fix(fixer) {
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if (fixed) {
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return null;
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}
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fixed = true;
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return fixer.replaceTextRange([start, end], newCode);
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}
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body.slice(0, lastNonExportStatementIndex).forEach(node => {
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if (isNonExportStatement(node)) {
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return;
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}
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context.report({
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node,
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messageId: "error",
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fix
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});
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});
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}
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};
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}
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};

‎tests/lib/rules/exports-last.js‎

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"use strict";
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const { RuleTester } = require("eslint");
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const rule = require("../../../lib/rules/exports-last");
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/**
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* @param {string} type
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* @returns {messageId: string, type: string}
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*/
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function error(type) {
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return {
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messageId: "error",
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type
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};
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}
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new RuleTester({
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parser: require.resolve("@typescript-eslint/parser"),
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parserOptions: {
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ecmaVersion: 2015,
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ecmaFeatures: {
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jsx: true
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},
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lib: ["dom", "dom.iterable", "esnext"],
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sourceType: "module"
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}
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}).run("exports-last", rule, {
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valid: [
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// // Empty file
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// "// comment",
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// `
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// const foo = 'bar'
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// const bar = 'baz'
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// `,
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// `
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// const foo = 'bar'
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// export {foo}
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// `,
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// `
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// const foo = 'bar'
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// export default foo
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// `,
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// // Only exports
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// `
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// export default foo
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// export const bar = true
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// `,
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// `
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// const foo = 'bar'
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// export default foo
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// export const bar = true
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// `,
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// // Multiline export
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// `
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// const foo = 'bar'
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// export default function bar () {
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// const very = 'multiline'
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// }
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// export const baz = true
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// `,
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// // Many exports
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// `
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// const foo = 'bar'
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// export default foo
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// export const so = 'many'
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// export const exports = ':)'
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// export const i = 'cant'
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// export const even = 'count'
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// export const how = 'many'
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// `,
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// // Export all
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// `
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// export * from './foo'
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// `
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],
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invalid: [
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// Default export before variable declaration
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{
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code: `export default 'bar'
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const bar = true`,
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output: `const bar = true
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export default 'bar'`,
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errors: [error("ExportDefaultDeclaration")]
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},
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// Named export before variable declaration
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{
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code: `export const foo = 'bar'
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const bar = true`,
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output: `const bar = true
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export const foo = 'bar'`,
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errors: [error("ExportNamedDeclaration")]
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},
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// Export all before variable declaration
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{
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code: `export * from './foo'
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const bar = true`,
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output: `const bar = true
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export * from './foo'`,
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errors: [error("ExportAllDeclaration")]
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},
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// Many exports arround variable declaration
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{
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code: `export default 'such foo many bar'
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export const so = 'many'
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const foo = 'bar'
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export const exports = ':)'
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const hoge = 'bar'
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export const i = 'cant'
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export const even = 'count'
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export const how = 'many'`,
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output: `const foo = 'bar'
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const hoge = 'bar'
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export default 'such foo many bar'
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export const so = 'many'
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export const exports = ':)'
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export const i = 'cant'
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export const even = 'count'
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export const how = 'many'`,
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errors: [
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error("ExportDefaultDeclaration"),
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error("ExportNamedDeclaration"),
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error("ExportNamedDeclaration")
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]
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}
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]
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});

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