Add rule to enforce default import aliases

Author: mic4ael

CHANGELOG.md

@@ -4,6 +4,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This change log adheres to standards from [Keep a CHANGELOG](http://keepachangelog.com).
 
 ## [Unreleased]
+- Add [`rename-default-import`] rule: Enforce default import naming
 
 ### Added
 - [`group-exports`]: make aggregate module exports valid ([#1472], thanks [@atikenny])
@@ -606,6 +607,7 @@ for info on changes for earlier releases.
 [`order`]: ./docs/rules/order.md
 [`prefer-default-export`]: ./docs/rules/prefer-default-export.md
 [`unambiguous`]: ./docs/rules/unambiguous.md
+[`rename-default-import`]: ./docs/rules/rename-default-import.md
 
 [`memo-parser`]: ./memo-parser/README.md
 

README.md

@@ -94,6 +94,7 @@ This plugin intends to support linting of ES2015+ (ES6+) import/export syntax, a
 * Forbid anonymous values as default exports ([`no-anonymous-default-export`])
 * Prefer named exports to be grouped together in a single export declaration ([`group-exports`])
 * Enforce a leading comment with the webpackChunkName for dynamic imports ([`dynamic-import-chunkname`])
+* Enforce a specific binding name for the default package import ([`rename-default-import`])
 
 [`first`]: ./docs/rules/first.md
 [`exports-last`]: ./docs/rules/exports-last.md
@@ -111,6 +112,7 @@ This plugin intends to support linting of ES2015+ (ES6+) import/export syntax, a
 [`no-default-export`]: ./docs/rules/no-default-export.md
 [`no-named-export`]: ./docs/rules/no-named-export.md
 [`dynamic-import-chunkname`]: ./docs/rules/dynamic-import-chunkname.md
+[`rename-default-import`]: ./docs/rules/rename-default-import.md
 
 ## Support
 

docs/rules/rename-default-import.md

@@ -0,0 +1,63 @@
+# import/rename-default-import
+
+This rule will enforce a specific binding name for a default package import.
+Works for ES6 imports and CJS require.
+
+
+## Rule Details
+
+Given:
+
+There is a package `prop-types` with a default export
+
+and
+
+```json
+// .eslintrc
+{
+  "rules": {
+    "import/rename-default-import": [
+      "warn", {
+        "prop-types": "PropTypes", // key: name of the module, value: desired binding for default import
+      }
+    ]
+  }
+}
+```
+
+The following is considered valid:
+
+```js
+import {default as PropTypes} from 'prop-types'
+
+import PropTypes from 'prop-types'
+```
+
+```js
+const PropTypes = require('prop-types');
+```
+
+...and the following cases are reported:
+
+```js
+import propTypes from 'prop-types';
+import {default as propTypes} from 'prop-types';
+```
+
+```js
+const propTypes = require('prop-types');
+```
+
+## When not to use it
+
+As long as you don't want to enforce specific naming for default imports.
+
+## Options
+
+This rule accepts an object which is a mapping
+between package name and the binding name that should be used for default imports.
+For example, a configuration like the one below
+
+`{'prop-types': 'PropTypes'}`
+
+specifies that default import for the package `prop-types` should be aliased to `PropTypes`.

src/index.js

@@ -39,6 +39,7 @@ export const rules = {
   'no-unassigned-import': require('./rules/no-unassigned-import'),
   'no-useless-path-segments': require('./rules/no-useless-path-segments'),
   'dynamic-import-chunkname': require('./rules/dynamic-import-chunkname'),
+  'rename-default-import': require('./rules/rename-default-import'),
 
   // export
   'exports-last': require('./rules/exports-last'),

src/rules/rename-default-import.js

@@ -0,0 +1,182 @@
+/**
+ * @fileoverview Rule to enforce aliases for default imports
+ * @author Michał Kołodziejski
+ */
+
+import docsUrl from '../docsUrl'
+import has from 'has'
+
+
+function isDefaultImport(specifier) {
+  if (specifier.type === 'ImportDefaultSpecifier') {
+    return true
+  }
+  if (specifier.type === 'ImportSpecifier' && specifier.imported.name === 'default') {
+    return true
+  }
+  return false
+}
+
+function isCommonJSImport(declaration) {
+  const variableInit = declaration.init
+  if (variableInit.type === 'CallExpression') {
+    return variableInit.callee.name === 'require'
+  }
+  return false
+}
+
+function handleImport(
+  context,
+  node,
+  specifierOrDeclaration,
+  packageName,
+  importAlias,
+  exportedIdentifiers
+) {
+  const mappings = context.options[0] || {}
+
+  if (!has(mappings, packageName) || mappings[packageName] === importAlias) {
+    return
+  }
+
+  let declaredVariables
+  if (specifierOrDeclaration.type === 'VariableDeclarator') {
+    declaredVariables = context.getDeclaredVariables(specifierOrDeclaration.parent)[0]
+  } else {
+    declaredVariables = context.getDeclaredVariables(specifierOrDeclaration)[0]
+  }
+
+  const references = declaredVariables ? declaredVariables.references : []
+  const skipFixing = exportedIdentifiers.indexOf(importAlias) !== -1
+
+  context.report({
+    node: node,
+    message: `Default import from '${packageName}' should be aliased to `
+            + `${mappings[packageName]}, not ${importAlias}`,
+    fix: skipFixing ? null : fixImportOrRequire(specifierOrDeclaration, mappings[packageName]),
+  })
+
+  for (const variableReference of references) {
+    if (specifierOrDeclaration.type === 'VariableDeclarator' && variableReference.init) {
+      continue
+    }
+
+    context.report({
+      node: variableReference.identifier,
+      message: `Using incorrect binding name '${variableReference.identifier.name}' `
+              + `instead of ${mappings[packageName]} for `
+              + `default import from package ${packageName}`,
+      fix: fixer => {
+        if (skipFixing) {
+          return
+        }
+
+        return fixer.replaceText(variableReference.identifier, mappings[packageName])
+      },
+    })
+  }
+}
+
+function fixImportOrRequire(node, text) {
+  return function(fixer) {
+    let newAlias = text
+    let nodeOrToken
+    if (node.type === 'VariableDeclarator') {
+      nodeOrToken = node.id
+      newAlias = text
+    } else {
+      nodeOrToken = node
+      if (node.imported && node.imported.name === 'default') {
+        newAlias = `default as ${text}`
+      } else {
+        newAlias = text
+      }
+    }
+
+    return fixer.replaceText(nodeOrToken, newAlias)
+  }
+}
+
+module.exports = {
+  meta: {
+    docs: {
+      url: docsUrl('rename-default-import'),
+      recommended: false,
+    },
+    schema: [
+      {
+        type: 'object',
+        minProperties: 1,
+        additionalProperties: {
+          type: 'string',
+        },
+      },
+    ],
+    fixable: 'code',
+  },
+  create: function(context) {
+    const exportedIdentifiers = []
+    return {
+      'Program': function(programNode) {
+        const {body} = programNode
+
+        body.forEach((node) => {
+          if (node.type === 'ExportNamedDeclaration') {
+            node.specifiers.forEach((specifier) => {
+              const {exported: {name}} = specifier
+              if (exportedIdentifiers.indexOf(name) === -1) {
+                exportedIdentifiers.push(name)
+              }
+            })
+          }
+        })
+      },
+      'ImportDeclaration:exit': function(node) {
+        const {source, specifiers} = node
+        const {options} = context
+
+        if (options.length === 0) {
+          return
+        }
+
+        for (const specifier of specifiers) {
+          if (!isDefaultImport(specifier)) {
+            continue
+          }
+
+          handleImport(
+            context,
+            source,
+            specifier,
+            source.value,
+            specifier.local.name,
+            exportedIdentifiers
+          )
+        }
+      },
+      'VariableDeclaration:exit': function(node) {
+        const {declarations} = node
+        const {options} = context
+
+        if (options.length === 0) {
+          return
+        }
+
+        for (const declaration of declarations) {
+          if (!isCommonJSImport(declaration) || context.getScope(declaration).type !== 'module') {
+            continue
+          }
+
+          handleImport(
+            context,
+            node,
+            declaration,
+            declaration.init.arguments[0].value,
+            declaration.id.name,
+            exportedIdentifiers
+          )
+        }
+      },
+    }
+  },
+}