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Add the foundation for the group-exports rule
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‎docs/rules/group-exports.md‎

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# @croutonn/group-exports
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> (TODO: summary)
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(TODO: why is this rule useful?)
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## Rule Details
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(TODO: how does this rule check code?)
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## Options
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(TODO: what do options exist?)

‎lib/rules/group-exports.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("eslint").Rule.RuleContext} RuleContext
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* @typedef {import("eslint").Rule.RuleListener} RuleListener
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* @typedef {import("estree").Node} ASTNode
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*/
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const errors = {
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ExportNamedDeclaration: "Multiple named export declarations; consolidate all named exports into a single export declaration",
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AssignmentExpression: "Multiple CommonJS exports; consolidate all exports into a single assignment to `module.exports`"
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};
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/**
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* Returns an array with names of the properties in the accessor chain for MemberExpression nodes
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*
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* Example:
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*
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* `module.exports = {}` => ['module', 'exports']
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* `module.exports.property = true` => ['module', 'exports', 'property']
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* @param {Node} node AST Node (MemberExpression)
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* @returns {Array} Array with the property names in the chain
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* @private
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*/
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function accessorChain(node) {
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const chain = [];
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let target = node;
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do {
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chain.unshift(target.property.name);
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if (target.object.type === "Identifier") {
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chain.unshift(target.object.name);
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break;
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}
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target = target.object;
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} while (target.type === "MemberExpression");
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return chain;
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}
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/**
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* Create Rule
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* @param {RuleContext} context rule context
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* @returns {RuleListener} rule listener
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*/
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function create(context) {
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const nodes = {
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modules: {
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set: new Set(),
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sources: {}
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},
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types: {
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set: new Set(),
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sources: {}
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},
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commonjs: {
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set: new Set()
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}
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};
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return {
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ExportNamedDeclaration(node) {
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const target = node.exportKind === "type" ? nodes.types : nodes.modules;
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if (!node.source) {
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target.set.add(node);
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} else if (Array.isArray(target.sources[node.source.value])) {
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target.sources[node.source.value].push(node);
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} else {
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target.sources[node.source.value] = [node];
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}
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},
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AssignmentExpression(node) {
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if (node.left.type !== "MemberExpression") {
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return;
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}
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const chain = accessorChain(node.left);
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// Assignments to module.exports
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// Deeper assignments are ignored since they just modify what's already being exported
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// (ie. module.exports.exported.prop = true is ignored)
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if (chain[0] === "module" && chain[1] === "exports" && chain.length <= 3) {
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nodes.commonjs.set.add(node);
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return;
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}
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// Assignments to exports (exports.* = *)
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if (chain[0] === "exports" && chain.length === 2) {
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nodes.commonjs.set.add(node);
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}
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},
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"Program:exit": function onExit() {
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// Report multiple `export` declarations (ES2015 modules)
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if (nodes.modules.set.size > 1) {
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nodes.modules.set.forEach(node => {
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context.report({
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node,
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messageId: node.type
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});
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});
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}
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// Report multiple `aggregated exports` from the same module (ES2015 modules)
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Object.values(nodes.modules.sources)
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.filter(nodesWithSource => Array.isArray(nodesWithSource) && nodesWithSource.length > 1).flat()
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.forEach(node => {
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context.report({
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node,
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messageId: node.type
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});
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});
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// Report multiple `export type` declarations (FLOW ES2015 modules)
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if (nodes.types.set.size > 1) {
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nodes.types.set.forEach(node => {
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context.report({
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node,
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messageId: node.type
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});
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});
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}
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// Report multiple `aggregated type exports` from the same module (FLOW ES2015 modules)
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Object.values(nodes.types.sources)
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.filter(nodesWithSource => Array.isArray(nodesWithSource) && nodesWithSource.length > 1).flat()
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.forEach(node => {
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context.report({
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node,
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messageId: node.type
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});
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});
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// Report multiple `module.exports` assignments (CommonJS)
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if (nodes.commonjs.set.size > 1) {
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nodes.commonjs.set.forEach(node => {
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context.report({
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node,
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messageId: node.type
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});
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});
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}
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}
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};
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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: "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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category: "Best Practices",
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recommended: true,
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url: "https://github.com/croutonn/eslint-plugin/blob/main/docs/rules/group-exports.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
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};

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