Add import-order rule

CHANGELOG.md

@@ -9,6 +9,7 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 - add [`no-extraneous-dependencies`] rule ([#241], thanks [@jfmengels])
 - add [`extensions`] rule ([#250], thanks [@lo1tuma])
 - add [`no-nodejs-modules`] rule ([#261], thanks [@jfmengels])
+- add [`order`] rule ([#247], thanks [@jfmengels])
 - consider `resolve.fallback` config option in the webpack resolver ([#254])
 
 ### Changed
@@ -155,9 +156,6 @@ for info on changes for earlier releases.
 [`imports-first`]: ./docs/rules/imports-first.md
 [`no-nodejs-modules`]: ./docs/rules/no-nodejs-modules.md
 
-[#256]: https://github.com/benmosher/eslint-plugin-import/pull/256
-[#254]: https://github.com/benmosher/eslint-plugin-import/pull/254
-[#250]: https://github.com/benmosher/eslint-plugin-import/pull/250
 [#243]: https://github.com/benmosher/eslint-plugin-import/pull/243
 [#241]: https://github.com/benmosher/eslint-plugin-import/pull/241
 [#239]: https://github.com/benmosher/eslint-plugin-import/pull/239
@@ -198,5 +196,3 @@ for info on changes for earlier releases.
 [@singles]: https://github.com/singles
 [@jfmengels]: https://github.com/jfmengels
 [@dmnd]: https://github.com/dmnd
-[@lo1tuma]: https://github.com/lo1tuma
-[@lemonmade]: https://github.com/lemonmade

README.md

@@ -53,11 +53,13 @@ This plugin intends to support linting of ES2015+ (ES6+) import/export syntax, a
 * Report repeated import of the same module in multiple places ([`no-duplicates`])
 * Report namespace imports ([`no-namespace`])
 * Ensure consistent use of file extension within the import path ([`extensions`])
+* Enforce a convention in module import order ([`order`])
 
 [`imports-first`]: ./docs/rules/imports-first.md
 [`no-duplicates`]: ./docs/rules/no-duplicates.md
 [`no-namespace`]: ./docs/rules/no-namespace.md
 [`extensions`]: ./docs/rules/extensions.md
+[`order`]: ./docs/rules/order.md
 
 
 ## Installation

docs/rules/order.md

@@ -0,0 +1,91 @@
+# Enforce a convention in module import order
+
+Enforce a convention in the order of `require()` / `import` statements. The order is as shown in the following example:
+
+```js
+// 1. node "builtins"
+import fs from 'fs';
+import path from 'path';
+// 2. "external" modules
+import _ from 'lodash';
+import chalk from 'chalk';
+// 3. "internal" modules
+// (if you have configured your path or webpack to handle your internal paths differently)
+import foo from 'src/foo';
+// 4. modules from a "parent" directory
+import foo from '../foo';
+import qux from '../../foo/qux';
+// 5. "sibling" modules from the same or a sibling's directory
+import bar from './bar';
+import baz from './bar/baz';
+// 6. "index" of the current directory
+import main from './';
+```
+
+Unassigned imports are ignored, as the order they are imported in may be important.
+
+Statements using the ES6 `import` syntax must appear before any `require()` statements.
+
+
+## Fail
+
+```js
+import _ from 'lodash';
+import path from 'path'; // `path` import should occur before import of `lodash`
+
+// -----
+
+var _ = require('lodash');
+var path = require('path'); // `path` import should occur before import of `lodash`
+
+// -----
+
+var path = require('path');
+import foo from './foo'; // `import` statements must be before `require` statement
+```
+
+
+## Pass
+
+```js
+import path from 'path';
+import _ from 'lodash';
+
+// -----
+
+var path = require('path');
+var _ = require('lodash');
+
+// -----
+
+// Allowed as ̀`babel-register` is not assigned.
+require('babel-register');
+var path = require('path');
+
+// -----
+
+// Allowed as `import` must be before `require`
+import foo from './foo';
+var path = require('path');
+```
+
+## Options
+
+This rule supports the following options:
+
+`groups`: How groups are defined, and the order to respect. `groups` must be an array of `string` or [`string`]. The only allowed `string`s are: `"builtin"`, `"external"`, `"internal"`, `"parent"`, `"sibling"`, `"index"`. The enforced order is the same as the order of each element in a group. Omitted types are implicitly grouped together as the last element. Example:
+```js
+[
+  'builtin', // Built-in types are first
+  ['sibling', 'parent'], // Then sibling and parent types. They can be mingled together
+  'index', // Then the index file
+  // Then the rest: internal and external type
+]
+```
+The default value is `["builtin", "external", "internal", "parent", "sibling", "index"]`.
+
+You can set the options like this:
+
+```js
+"import/order": ["error", {"groups": ["index", "sibling", "parent", "internal", "external", "builtin"]}]
+```

package.json

@@ -73,6 +73,7 @@
     "eslint-import-resolver-node": "^0.2.0",
     "lodash.cond": "^4.3.0",
     "lodash.endswith": "^4.0.1",
+    "lodash.find": "^4.3.0",
     "object-assign": "^4.0.1",
     "pkg-up": "^1.0.0"
   }

src/core/importType.js

@@ -1,6 +1,6 @@
 import cond from 'lodash.cond'
 import builtinModules from 'builtin-modules'
-import { basename, join } from 'path'
+import { join } from 'path'
 
 import resolve from './resolve'
 
@@ -18,7 +18,12 @@ function isExternalModule(name, path) {
   return (!path || -1 < path.indexOf(join('node_modules', name)))
 }
 
-function isProjectModule(name, path) {
+const scopedRegExp = /^@\w+\/\w+/
+function isScoped(name) {
+  return scopedRegExp.test(name)
+}
+
+function isInternalModule(name, path) {
   if (!externalModuleRegExp.test(name)) return false
   return (path && -1 === path.indexOf(join('node_modules', name)))
 }
@@ -28,8 +33,7 @@ function isRelativeToParent(name) {
 }
 
 const indexFiles = ['.', './', './index', './index.js']
-function isIndex(name, path) {
-  if (path) return basename(path).split('.')[0] === 'index'
+function isIndex(name) {
   return indexFiles.indexOf(name) !== -1
 }
 
@@ -40,7 +44,8 @@ function isRelativeToSibling(name) {
 const typeTest = cond([
   [isBuiltIn, constant('builtin')],
   [isExternalModule, constant('external')],
-  [isProjectModule, constant('project')],
+  [isScoped, constant('external')],
+  [isInternalModule, constant('internal')],
   [isRelativeToParent, constant('parent')],
   [isIndex, constant('index')],
   [isRelativeToSibling, constant('sibling')],

src/core/staticRequire.js

@@ -1,6 +1,7 @@
 // todo: merge with module visitor
 export default function isStaticRequire(node) {
   return node &&
+    node.callee &&
     node.callee.type === 'Identifier' &&
     node.callee.name === 'require' &&
     node.arguments.length === 1 &&

src/index.js

@@ -16,6 +16,7 @@ export const rules = {
   'imports-first': require('./rules/imports-first'),
   'no-extraneous-dependencies': require('./rules/no-extraneous-dependencies'),
   'no-nodejs-modules': require('./rules/no-nodejs-modules'),
+  'order': require('./rules/order'),
 
   // metadata-based
   'no-deprecated': require('./rules/no-deprecated'),

src/rules/order.js

@@ -0,0 +1,175 @@
+'use strict'
+
+import find from 'lodash.find'
+import importType from '../core/importType'
+import isStaticRequire from '../core/staticRequire'
+
+const defaultGroups = ['builtin', 'external', 'parent', 'sibling', 'index']
+
+// REPORTING
+
+function reverse(array) {
+  return array.map(function (v) {
+    return {
+      name: v.name,
+      rank: -v.rank,
+      node: v.node,
+    }
+  }).reverse()
+}
+
+function findOutOfOrder(imported) {
+  if (imported.length === 0) {
+    return []
+  }
+  let maxSeenRankNode = imported[0]
+  return imported.filter(function (importedModule) {
+    const res = importedModule.rank < maxSeenRankNode.rank
+    if (maxSeenRankNode.rank < importedModule.rank) {
+      maxSeenRankNode = importedModule
+    }
+    return res
+  })
+}
+
+function report(context, imported, outOfOrder, order) {
+  outOfOrder.forEach(function (imp) {
+    const found = find(imported, function hasHigherRank(importedItem) {
+      return importedItem.rank > imp.rank
+    })
+    context.report(imp.node, '`' + imp.name + '` import should occur ' + order +
+      ' import of `' + found.name + '`')
+  })
+}
+
+function makeReport(context, imported) {
+  const outOfOrder = findOutOfOrder(imported)
+  if (!outOfOrder.length) {
+    return
+  }
+  // There are things to report. Try to minimize the number of reported errors.
+  const reversedImported = reverse(imported)
+  const reversedOrder = findOutOfOrder(reversedImported)
+  if (reversedOrder.length < outOfOrder.length) {
+    report(context, reversedImported, reversedOrder, 'after')
+    return
+  }
+  report(context, imported, outOfOrder, 'before')
+}
+
+// DETECTING
+
+function computeRank(context, ranks, name, type) {
+  return ranks[importType(name, context)] +
+    (type === 'import' ? 0 : 100)
+}
+
+function registerNode(context, node, name, type, ranks, imported) {
+  const rank = computeRank(context, ranks, name, type)
+  if (rank !== -1) {
+    imported.push({name, rank, node})
+  }
+}
+
+function isInVariableDeclarator(node) {
+  return node &&
+    (node.type === 'VariableDeclarator' || isInVariableDeclarator(node.parent))
+}
+
+const types = ['builtin', 'external', 'internal', 'parent', 'sibling', 'index']
+
+// Creates an object with type-rank pairs.
+// Example: { index: 0, sibling: 1, parent: 1, external: 1, builtin: 2, internal: 2 }
+// Will throw an error if it contains a type that does not exist, or has a duplicate
+function convertGroupsToRanks(groups) {
+  const rankObject = groups.reduce(function(res, group, index) {
+    if (typeof group === 'string') {
+      group = [group]
+    }
+    group.forEach(function(groupItem) {
+      if (types.indexOf(groupItem) === -1) {
+        throw new Error('Incorrect configuration of the rule: Unknown type `' +
+          JSON.stringify(groupItem) + '`')
+      }
+      if (res[groupItem] !== undefined) {
+        throw new Error('Incorrect configuration of the rule: `' + groupItem + '` is duplicated')
+      }
+      res[groupItem] = index
+    })
+    return res
+  }, {})
+
+  const omittedTypes = types.filter(function(type) {
+    return rankObject[type] === undefined
+  })
+
+  return omittedTypes.reduce(function(res, type) {
+    res[type] = groups.length
+    return res
+  }, rankObject)
+}
+
+module.exports = function importOrderRule (context) {
+  const options = context.options[0] || {}
+  let ranks
+
+  try {
+    ranks = convertGroupsToRanks(options.groups || defaultGroups)
+  } catch (error) {
+    // Malformed configuration
+    return {
+      Program: function(node) {
+        context.report(node, error.message)
+      },
+    }
+  }
+  let imported = []
+  let level = 0
+
+  function incrementLevel() {
+    level++
+  }
+  function decrementLevel() {
+    level--
+  }
+
+  return {
+    ImportDeclaration: function handleImports(node) {
+      if (node.specifiers.length) { // Ignoring unassigned imports
+        const name = node.source.value
+        registerNode(context, node, name, 'import', ranks, imported)
+      }
+    },
+    CallExpression: function handleRequires(node) {
+      if (level !== 0 || !isStaticRequire(node) || !isInVariableDeclarator(node.parent)) {
+        return
+      }
+      const name = node.arguments[0].value
+      registerNode(context, node, name, 'require', ranks, imported)
+    },
+    'Program:exit': function reportAndReset() {
+      makeReport(context, imported)
+      imported = []
+    },
+    FunctionDeclaration: incrementLevel,
+    FunctionExpression: incrementLevel,
+    ArrowFunctionExpression: incrementLevel,
+    BlockStatement: incrementLevel,
+    'FunctionDeclaration:exit': decrementLevel,
+    'FunctionExpression:exit': decrementLevel,
+    'ArrowFunctionExpression:exit': decrementLevel,
+    'BlockStatement:exit': decrementLevel,
+  }
+}
+
+module.exports.schema = [
+  {
+    type: 'object',
+    properties: {
+      groups: {
+        type: 'array',
+      },
+    },
+    additionalProperties: false,
+  },
+]