Add no-extraneous-dependencies rule

package.json

@@ -65,11 +65,14 @@
     "eslint": "2.x"
   },
   "dependencies": {
+    "builtin-modules": "^1.1.1",
     "doctrine": "1.2.0",
     "es6-map": "^0.1.3",
     "es6-set": "^0.1.4",
     "es6-symbol": "*",
     "eslint-import-resolver-node": "^0.2.0",
-    "object-assign": "^4.0.1"
+    "lodash.cond": "^4.3.0",
+    "object-assign": "^4.0.1",
+    "pkg-up": "^1.0.0"
   }
 }

src/core/importType.js

@@ -0,0 +1,39 @@
+'use strict'
+
+import cond from 'lodash.cond'
+import builtinModules from 'builtin-modules'
+
+function constant(value) {
+  return () => value
+}
+
+function isBuiltIn(name) {
+  return builtinModules.indexOf(name) !== -1
+}
+
+const externalModuleRegExp = /^\w/
+function isExternalModule(name) {
+  return externalModuleRegExp.test(name)
+}
+
+function isRelativeToParent(name) {
+  return name.indexOf('../') === 0
+}
+
+const indexFiles = ['.', './', './index', './index.js']
+function isIndex(name) {
+  return indexFiles.indexOf(name) !== -1
+}
+
+function isRelativeToSibling(name) {
+  return name.indexOf('./') === 0
+}
+
+export default cond([
+  [isBuiltIn, constant('builtin')],
+  [isExternalModule, constant('external')],
+  [isRelativeToParent, constant('parent')],
+  [isIndex, constant('index')],
+  [isRelativeToSibling, constant('sibling')],
+  [constant(true), constant('unknown')],
+])

src/core/staticRequire.js

@@ -0,0 +1,7 @@
+export default function isStaticRequire(node) {
+  return node &&
+    node.callee.type === 'Identifier' &&
+    node.callee.name === 'require' &&
+    node.arguments.length === 1 &&
+    node.arguments[0].type === 'Literal'
+}

src/index.js

@@ -11,6 +11,7 @@ export const rules = {
   'no-amd': require('./rules/no-amd'),
   'no-duplicates': require('./rules/no-duplicates'),
   'imports-first': require('./rules/imports-first'),
+  'no-extraneous-dependencies': require('./rules/no-extraneous-dependencies'),
 
   // metadata-based
   'no-deprecated': require('./rules/no-deprecated'),

src/rules/no-extraneous-dependencies.js

@@ -0,0 +1,76 @@
+import fs from 'fs'
+import pkgUp from 'pkg-up'
+import importType from '../core/importType'
+import isStaticRequire from '../core/staticRequire'
+
+function getDependencies() {
+  const filepath = pkgUp.sync()
+	if (!filepath) {
+		return null
+	}
+
+	try {
+		const packageContent = JSON.parse(fs.readFileSync(filepath, 'utf8'))
+		return {
+      dependencies: packageContent.dependencies || {},
+      devDependencies: packageContent.devDependencies || {},
+    }
+	} catch (e) {
+		return null
+	}
+}
+
+function missingErrorMessage(packageName) {
+	return `'${packageName}' is not listed in the project's dependencies. ` +
+		`Run 'npm i -S ${packageName}' to add it`
+}
+
+function devDepErrorMessage(packageName) {
+	return `'${packageName}' is not listed in the project's dependencies, not devDependencies.`
+}
+
+function reportIfMissing(context, deps, allowDevDeps, node, name) {
+  if (importType(name) !== 'external') {
+    return
+  }
+  const packageName = name.split('/')[0]
+
+  if (deps.dependencies[packageName] === undefined) {
+    if (!allowDevDeps) {
+      context.report(node, devDepErrorMessage(packageName))
+    } else if (deps.devDependencies[packageName] === undefined) {
+      context.report(node, missingErrorMessage(packageName))
+    }
+  }
+}
+
+module.exports = function (context) {
+  const options = context.options[0] || {}
+  const allowDevDeps = options.devDependencies !== false
+  const deps = getDependencies()
+
+  if (!deps) {
+    return {}
+  }
+
+  return {
+    ImportDeclaration: function (node) {
+      reportIfMissing(context, deps, allowDevDeps, node, node.source.value)
+    },
+    CallExpression: function handleRequires(node) {
+      if (isStaticRequire(node)) {
+        reportIfMissing(context, deps, allowDevDeps, node, node.arguments[0].value)
+      }
+    },
+  }
+}
+
+module.exports.schema = [
+  {
+    'type': 'object',
+    'properties': {
+      'devDependencies': { 'type': 'boolean' },
+    },
+    'additionalProperties': false,
+  },
+]

tests/src/core/importType.js

@@ -0,0 +1,41 @@
+import { expect } from 'chai'
+import importType from 'core/importType'
+
+describe('importType(name)', function () {
+  it("should return 'builtin' for node.js modules", function() {
+    expect(importType('fs')).to.equal('builtin')
+    expect(importType('path')).to.equal('builtin')
+  })
+
+  it("should return 'external' for non-builtin modules without a relative path", function() {
+    expect(importType('lodash')).to.equal('external')
+    expect(importType('async')).to.equal('external')
+    expect(importType('chalk')).to.equal('external')
+    expect(importType('foo')).to.equal('external')
+    expect(importType('lodash.find')).to.equal('external')
+    expect(importType('lodash/fp')).to.equal('external')
+  })
+
+  it("should return 'parent' for internal modules that go through the parent", function() {
+    expect(importType('../foo')).to.equal('parent')
+    expect(importType('../../foo')).to.equal('parent')
+    expect(importType('../bar/foo')).to.equal('parent')
+  })
+
+  it("should return 'sibling' for internal modules that are connected to one of the siblings", function() {
+    expect(importType('./foo')).to.equal('sibling')
+    expect(importType('./foo/bar')).to.equal('sibling')
+  })
+
+  it("should return 'index' for sibling index file", function() {
+    expect(importType('.')).to.equal('index')
+    expect(importType('./')).to.equal('index')
+    expect(importType('./index')).to.equal('index')
+    expect(importType('./index.js')).to.equal('index')
+  })
+
+  it("should return 'unknown' for any unhandled cases", function() {
+    expect(importType('/malformed')).to.equal('unknown')
+    expect(importType('   foo')).to.equal('unknown')
+  })
+})

tests/src/rules/no-extraneous-dependencies.js

@@ -0,0 +1,55 @@
+import { test } from '../utils'
+
+import { RuleTester } from 'eslint'
+
+const ruleTester = new RuleTester()
+    , rule = require('rules/no-extraneous-dependencies')
+
+ruleTester.run('no-extraneous-dependencies', rule, {
+  valid: [
+    test({ code: 'import "lodash.cond"'}),
+    test({ code: 'import "pkg-up"'}),
+    test({ code: 'import foo, { bar } from "lodash.cond"'}),
+    test({ code: 'import foo, { bar } from "pkg-up"'}),
+    test({ code: 'import "eslint"'}),
+    test({ code: 'import "eslint/lib/api"'}),
+    test({ code: 'require("lodash.cond")'}),
+    test({ code: 'require("pkg-up")'}),
+    test({ code: 'var foo = require("lodash.cond")'}),
+    test({ code: 'var foo = require("pkg-up")'}),
+    test({ code: 'import "fs"'}),
+    test({ code: 'import "./foo"'}),
+  ],
+  invalid: [
+    test({
+      code: 'import "not-a-dependency"',
+      errors: [{
+        ruleId: 'no-extraneous-dependencies',
+        message: '\'not-a-dependency\' is not listed in the project\'s dependencies. Run \'npm i -S not-a-dependency\' to add it',
+      }],
+    }),
+    test({
+      code: 'import "eslint"',
+      options: [{devDependencies: false}],
+      errors: [{
+        ruleId: 'no-extraneous-dependencies',
+        message: '\'eslint\' is not listed in the project\'s dependencies, not devDependencies.',
+      }],
+    }),
+    test({
+      code: 'var foo = require("not-a-dependency");',
+      errors: [{
+        ruleId: 'no-extraneous-dependencies',
+        message: '\'not-a-dependency\' is not listed in the project\'s dependencies. Run \'npm i -S not-a-dependency\' to add it',
+      }],
+    }),
+    test({
+      code: 'var eslint = require("eslint");',
+      options: [{devDependencies: false}],
+      errors: [{
+        ruleId: 'no-extraneous-dependencies',
+        message: '\'eslint\' is not listed in the project\'s dependencies, not devDependencies.',
+      }],
+    }),
+  ],
+})