eslint/tests/lib/rules/prefer-arrow-callback.js

   1 /**
   2  * @fileoverview Tests for prefer-arrow-callback rule.
   3  * @author Toru Nagashima
   4  */
   5
   6 "use strict";
   7
   8 //------------------------------------------------------------------------------
   9 // Requirements
  10 //------------------------------------------------------------------------------
  11
  12 const rule = require("../../../lib/rules/prefer-arrow-callback");
  13 const { RuleTester } = require("../../../lib/rule-tester");
  14
  15 //------------------------------------------------------------------------------
  16 // Tests
  17 //------------------------------------------------------------------------------
  18
  19 const errors = [{
  20     messageId: "preferArrowCallback",
  21     type: "FunctionExpression"
  22 }];
  23
  24 const ruleTester = new RuleTester({ parserOptions: { ecmaVersion: 6 } });
  25
  26 ruleTester.run("prefer-arrow-callback", rule, {
  27     valid: [
  28         "foo(a => a);",
  29         "foo(function*() {});",
  30         "foo(function() { this; });",
  31         { code: "foo(function bar() {});", options: [{ allowNamedFunctions: true }] },
  32         "foo(function() { (() => this); });",
  33         "foo(function() { this; }.bind(obj));",
  34         "foo(function() { this; }.call(this));",
  35         "foo(a => { (function() {}); });",
  36         "var foo = function foo() {};",
  37         "(function foo() {})();",
  38         "foo(function bar() { bar; });",
  39         "foo(function bar() { arguments; });",
  40         "foo(function bar() { arguments; }.bind(this));",
  41         "foo(function bar() { new.target; });",
  42         "foo(function bar() { new.target; }.bind(this));",
  43         "foo(function bar() { this; }.bind(this, somethingElse));"
  44     ],
  45     invalid: [
  46         {
  47             code: "foo(function bar() {});",
  48             output: "foo(() => {});",
  49             errors
  50         },
  51         {
  52             code: "foo(function() {});",
  53             output: "foo(() => {});",
  54             options: [{ allowNamedFunctions: true }],
  55             errors
  56         },
  57         {
  58             code: "foo(function bar() {});",
  59             output: "foo(() => {});",
  60             options: [{ allowNamedFunctions: false }],
  61             errors
  62         },
  63         {
  64             code: "foo(function() {});",
  65             output: "foo(() => {});",
  66             errors
  67         },
  68         {
  69             code: "foo(nativeCb || function() {});",
  70             output: "foo(nativeCb || (() => {}));",
  71             errors
  72         },
  73         {
  74             code: "foo(bar ? function() {} : function() {});",
  75             output: "foo(bar ? () => {} : () => {});",
  76             errors: [errors[0], errors[0]]
  77         },
  78         {
  79             code: "foo(function() { (function() { this; }); });",
  80             output: "foo(() => { (function() { this; }); });",
  81             errors
  82         },
  83         {
  84             code: "foo(function() { this; }.bind(this));",
  85             output: "foo(() => { this; });",
  86             errors
  87         },
  88         {
  89             code: "foo(bar || function() { this; }.bind(this));",
  90             output: "foo(bar || (() => { this; }));",
  91             errors
  92         },
  93         {
  94             code: "foo(function() { (() => this); }.bind(this));",
  95             output: "foo(() => { (() => this); });",
  96             errors
  97         },
  98         {
  99             code: "foo(function bar(a) { a; });",
 100             output: "foo((a) => { a; });",
 101             errors
 102         },
 103         {
 104             code: "foo(function(a) { a; });",
 105             output: "foo((a) => { a; });",
 106             errors
 107         },
 108         {
 109             code: "foo(function(arguments) { arguments; });",
 110             output: "foo((arguments) => { arguments; });",
 111             errors
 112         },
 113         {
 114             code: "foo(function() { this; });",
 115             output: null, // No fix applied
 116             options: [{ allowUnboundThis: false }],
 117             errors
 118         },
 119         {
 120             code: "foo(function() { (() => this); });",
 121             output: null, // No fix applied
 122             options: [{ allowUnboundThis: false }],
 123             errors
 124         },
 125         {
 126             code: "qux(function(foo, bar, baz) { return foo * 2; })",
 127             output: "qux((foo, bar, baz) => { return foo * 2; })",
 128             errors
 129         },
 130         {
 131             code: "qux(function(foo, bar, baz) { return foo * bar; }.bind(this))",
 132             output: "qux((foo, bar, baz) => { return foo * bar; })",
 133             errors
 134         },
 135         {
 136             code: "qux(function(foo, bar, baz) { return foo * this.qux; }.bind(this))",
 137             output: "qux((foo, bar, baz) => { return foo * this.qux; })",
 138             errors
 139         },
 140         {
 141             code: "foo(function() {}.bind(this, somethingElse))",
 142             output: "foo((() => {}).bind(this, somethingElse))",
 143             errors
 144         },
 145         {
 146             code: "qux(function(foo = 1, [bar = 2] = [], {qux: baz = 3} = {foo: 'bar'}) { return foo + bar; });",
 147             output: "qux((foo = 1, [bar = 2] = [], {qux: baz = 3} = {foo: 'bar'}) => { return foo + bar; });",
 148             errors
 149         },
 150         {
 151             code: "qux(function(baz, baz) { })",
 152             output: null, // Duplicate parameter names are a SyntaxError in arrow functions
 153             errors
 154         },
 155         {
 156             code: "qux(function( /* no params */ ) { })",
 157             output: "qux(( /* no params */ ) => { })",
 158             errors
 159         },
 160         {
 161             code: "qux(function( /* a */ foo /* b */ , /* c */ bar /* d */ , /* e */ baz /* f */ ) { return foo; })",
 162             output: "qux(( /* a */ foo /* b */ , /* c */ bar /* d */ , /* e */ baz /* f */ ) => { return foo; })",
 163             errors
 164         },
 165         {
 166             code: "qux(async function (foo = 1, bar = 2, baz = 3) { return baz; })",
 167             output: "qux(async (foo = 1, bar = 2, baz = 3) => { return baz; })",
 168             parserOptions: { ecmaVersion: 8 },
 169             errors
 170         },
 171         {
 172             code: "qux(async function (foo = 1, bar = 2, baz = 3) { return this; }.bind(this))",
 173             output: "qux(async (foo = 1, bar = 2, baz = 3) => { return this; })",
 174             parserOptions: { ecmaVersion: 8 },
 175             errors
 176         }
 177     ]
 178 });