fix: crash in from-map rule with identifiers as callbacks and some invalid fix suggestions. (fixes #344)

Author: freaktechnik

rules/from-map.js

@@ -4,7 +4,11 @@
  */
 "use strict";
 
-const { ARROW_FUNCTION_EXPRESSION } = require("../lib/type");
+const { ARROW_FUNCTION_EXPRESSION } = require("../lib/type"),
+    ALL_PARAMS = [
+        { name: 'item' },
+        { name: 'index' }
+    ];
 
 module.exports = {
     meta: {
@@ -21,11 +25,22 @@ module.exports = {
     },
     create(context) {
         return {
-            'CallExpression[callee.type="MemberExpression"] > MemberExpression[property.name="map"] > CallExpression[callee.type="MemberExpression"][callee.property.name="from"][callee.object.type="Identifier"][callee.object.name="Array"]'(node) {
+            'CallExpression[callee.type="MemberExpression"] > MemberExpression[property.name="map"][property] > CallExpression[callee.type="MemberExpression"][callee.property.name="from"][callee.object.type="Identifier"][callee.object.name="Array"]'(node) {
                 const parent = node,
-                    callee = node.parent;
+                    callee = node.parent,
+                    [
+                        mapCallback,
+                        mapThisArgument
+                    ] = callee.parent.arguments;
                 node = callee.parent;
 
+                if(mapCallback.type === "Identifier" ||
+                    mapCallback.params.length > ALL_PARAMS.length ||
+                    mapCallback.params.some((parameter) => parameter.type === "RestElement")
+                ) {
+                    return;
+                }
+
                 context.report({
                     node: callee.property,
                     loc: {
@@ -42,17 +57,14 @@ module.exports = {
                         // Merge the from and map callbacks
                         if(parent.arguments.length >= HAS_CBK) {
                             const OMIT_ITEM = 1,
-                                [
-                                    mapCallback,
-                                    mapThisArgument
-                                ] = node.arguments,
                                 [
                                     _, // eslint-disable-line no-unused-vars
                                     callback,
                                     thisArgument
                                 ] = parent.arguments,
-                                // Get the params names from the callback that has the most params (since the signature is identical).
-                                parameters = callback.params.length > mapCallback.params.length ? callback.params : mapCallback.params,
+                                parameters = callback.type !== "Identifier"
+                                    ? callback.params.length > mapCallback.params.length ? callback.params : mapCallback.params
+                                    : ALL_PARAMS,
                                 parameterString = parameters.map((p) => p.name).join(PARAM_SEPARATOR),
                                 getCallback = (cbk, targ, ps) => {
                                     const source = `(${sourceCode.getText(cbk)})`;

test/helpers/from-map-test-cases.mjs

@@ -2,7 +2,11 @@ export default {
     valid: [
         'array.map((t) => t.id)',
         'Array.from(iterable).some((t) => t !== "a")',
-        'Array.from(iterable, (t) => t.id)'
+        'Array.from(iterable, (t) => t.id)',
+        'Array.from(iterable, callback)',
+        'Array.from(iterable).map((u, i, a) => a[i])',
+        'Array.from(iterable).map(callback)',
+        'Array.from(iterable).map((...args) => args)'
     ],
     invalid: [
         {
@@ -58,6 +62,15 @@ export default {
                 line: 1
             } ],
             output: 'Array.from(iterable, function(u, i) { return (function(t) { return t[0]; }).call(b, (function(u, i) { return u.id; }).call(this, u, i), i); }, a)'
+        },
+        {
+            code: 'Array.from(iterable, mapper).map((u, i) => u.name)',
+            errors: [ {
+                messageId: 'useMapCb',
+                column: 1,
+                line: 1
+            } ],
+            output: 'Array.from(iterable, (item, index) => ((u, i) => u.name)((mapper).call(this, item, index), index))'
         }
     ]
 };