New rule: prefer-native-method (Fixes #221)

src/rules/prefer-native-method.js

@@ -0,0 +1,39 @@
+/**
+ * @fileoverview Rule to make sure certain native functions are used instead of lodash functions.
+ */
+'use strict'
+
+// ------------------------------------------------------------------------------
+// Rule Definition
+// ------------------------------------------------------------------------------
+
+const getDocsUrl = require('../util/getDocsUrl')
+
+module.exports = {
+    meta: {
+        docs: {
+            url: getDocsUrl('prefer-native-method')
+        },
+        fixable: 'code'
+    },
+
+    create(context) {
+        const {getLodashMethodVisitors} = require('../util/lodashUtil')
+        const {isAliasOfMethod} = require('../util/methodDataUtil')
+
+        const sourceCode = context.getSourceCode()
+
+        return getLodashMethodVisitors(context, (node, iteratee, {method, version}) => {
+            if (isAliasOfMethod(version, 'map', method)) {
+                context.report({
+                    node,
+                    message: 'Prefer \'Array.prototype.map\' over the lodash function.',
+                    fix(fixer) {
+                        const [firstArg, ...restArgs] = node.arguments
+                        return fixer.replaceText(node, `(${sourceCode.getText(firstArg)}).map(${restArgs.map(arg => sourceCode.getText(arg)).join(', ')})`)
+                    }
+                })
+            }
+        })
+    }
+}

tests/lib/rules/prefer-native-method.js

@@ -0,0 +1,63 @@
+'use strict'
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+const rule = require('../../../src/rules/prefer-native-method')
+const ruleTesterUtil = require('../testUtil/ruleTesterUtil')
+
+// ------------------------------------------------------------------------------
+// Tests
+// ------------------------------------------------------------------------------
+
+const ruleTester = ruleTesterUtil.getRuleTester()
+const {withDefaultPragma, fromVersion3WithDefaultPragma} = require('../testUtil/optionsUtil')
+ruleTester.run('prefer-native-method', rule, {
+    valid: [
+        ...[
+            '[1,2,3].map((i) => i)',
+            'arr.map((i) => i)'
+        ].map(withDefaultPragma),
+        ...[
+            'var x = arr.map(something, withSomething)'
+        ].map(fromVersion3WithDefaultPragma)
+    ],
+    invalid: [{
+        code: 'var x = _.map(arr, f)',
+        errors: [{message: 'Prefer \'Array.prototype.map\' over the lodash function.'}],
+        output: 'var x = (arr).map(f)'
+    }, {
+        code: 'import {map} from "lodash"; var x = map(arr, f)',
+        errors: [{message: 'Prefer \'Array.prototype.map\' over the lodash function.'}],
+        output: 'import {map} from "lodash"; var x = (arr).map(f)',
+        parserOptions: {
+            sourceType: 'module'
+        }
+    }, {
+        code: 'var x = _.map(arr, (i) => i)',
+        errors: [{message: 'Prefer \'Array.prototype.map\' over the lodash function.'}],
+        output: 'var x = (arr).map((i) => i)'
+    }, {
+        code: 'import {map as renamedMap} from "lodash"; var x = renamedMap(arr, (i) => i)',
+        errors: [{message: 'Prefer \'Array.prototype.map\' over the lodash function.'}],
+        output: 'import {map as renamedMap} from "lodash"; var x = (arr).map((i) => i)',
+        parserOptions: {
+            sourceType: 'module'
+        }
+    }, {
+        code: 'import {map as renamedMap} from "lodash"; var x = renamedMap(compact([1,2,3,null]), (i) => i)',
+        errors: [{message: 'Prefer \'Array.prototype.map\' over the lodash function.'}],
+        output: 'import {map as renamedMap} from "lodash"; var x = (compact([1,2,3,null])).map((i) => i)',
+        parserOptions: {
+            sourceType: 'module'
+        }
+    }, {
+        code: 'import {map} from "lodash"; var x = map(a ? b : c, (i) => i)',
+        errors: [{message: 'Prefer \'Array.prototype.map\' over the lodash function.'}],
+        output: 'import {map} from "lodash"; var x = (a ? b : c).map((i) => i)',
+        parserOptions: {
+            sourceType: 'module'
+        }
+    }].map(withDefaultPragma)
+})