Add new rule no-get-with-default

README.md

@@ -91,6 +91,7 @@ The `--fix` option on the command line automatically fixes problems reported by
 |  | [named-functions-in-promises](./docs/rules/named-functions-in-promises.md) | Enforces usage of named functions in promises |
 | :white_check_mark: | [new-module-imports](./docs/rules/new-module-imports.md) |  Use "New Module Imports" from Ember RFC #176 |
 | :white_check_mark: | [no-function-prototype-extensions](./docs/rules/no-function-prototype-extensions.md) | Prevents usage of Ember's `function` prototype extensions |
+| :car: | [no-get-with-default](./docs/rules/no-get-with-default.md) | Use the `||` operator instead of `getWithDefault` for more expected behaviors |
 | :car::wrench: | [no-get](./docs/rules/no-get.md) | Require ES5 getters instead of Ember's `get` / `getProperties` functions |
 | :white_check_mark: | [no-global-jquery](./docs/rules/no-global-jquery.md) | Prevents usage of global jQuery object |
 | :car: | [no-jquery](./docs/rules/no-jquery.md) | Disallow any usage of jQuery |

docs/rules/no-get-with-default.md

@@ -0,0 +1,41 @@
+# No `getWithDefault` (no-get-with-default)
+
+This rule attempts to catch and prevent the use of `getWithDefault`.
+
+## Rule Details
+
+Even though the behavior for `getWithDefault` is more defined such that it only falls back to the default value on `undefined`,
+its inconsistency with the native `||` is confusing to many developers who assume otherwise. This rule encourages developers to use
+the native `||` operator instead.
+
+In addition, [Nullish Coalescing Operator `??`](https://github.com/tc39/proposal-nullish-coalescing) will land in the JavaScript language soon so developers can leverage safe property access with native support instead of using `getWithDefault`.
+
+This rule **forbids** the following:
+
+```js
+const test = this.getWithDefault('key', []);
+```
+
+```js
+const test = getWithDefault(this, 'key', []);
+```
+
+This rule **allows** the following:
+
+```js
+const test = this.key === undefined ? [] : this.key;
+```
+
+```js
+ // the behavior of this is different because `test` would be assigned `[]` on any falsy value instead of on only `undefined`.
+const test = this.key || [];
+```
+
+## References
+
+- [RFC](https://github.com/emberjs/rfcs/pull/554/) to deprecate `getWithDefault`
+
+## Related Rules
+
+- [no-get](https://github.com/ember-cli/eslint-plugin-ember/blob/master/docs/rules/no-get.md)
+- [spec](http://api.emberjs.com/ember/3.13/functions/@ember%2Fobject/getWithDefault)

lib/index.js

@@ -26,6 +26,7 @@ module.exports = {
     'no-ember-testing-in-module-scope': require('./rules/no-ember-testing-in-module-scope'),
     'no-empty-attrs': require('./rules/no-empty-attrs'),
     'no-function-prototype-extensions': require('./rules/no-function-prototype-extensions'),
+    'no-get-with-default': require('./rules/no-get-with-default'),
     'no-get': require('./rules/no-get'),
     'no-global-jquery': require('./rules/no-global-jquery'),
     'no-incorrect-calls-with-inline-anonymous-functions': require('./rules/no-incorrect-calls-with-inline-anonymous-functions'),

lib/octane-rules.js

@@ -11,6 +11,7 @@ module.exports = {
   "ember/no-classic-classes": "error",
   "ember/no-classic-components": "error",
   "ember/no-computed-properties-in-native-classes": "error",
+  "ember/no-get-with-default": "error",
   "ember/no-get": "error",
   "ember/no-jquery": "error",
   "ember/require-tagless-components": "error"

lib/recommended-rules.js

@@ -29,6 +29,7 @@ module.exports = {
   "ember/no-ember-testing-in-module-scope": "error",
   "ember/no-empty-attrs": "off",
   "ember/no-function-prototype-extensions": "error",
+  "ember/no-get-with-default": "off",
   "ember/no-get": "off",
   "ember/no-global-jquery": "error",
   "ember/no-incorrect-calls-with-inline-anonymous-functions": "error",

lib/rules/no-get-with-default.js

@@ -0,0 +1,49 @@
+'use strict';
+
+const types = require('../utils/types');
+
+function makeErrorMessageForGetWithDefault(property, isImportedGetWithDefault) {
+  return isImportedGetWithDefault
+    ? 'Use `||` or the ternary operator instead of `getWithDefault()`.'
+    : 'Use `this.property || defaultValue` or the `this.property === undefined ? defaultValue : this.property` instead of `getWithDefault(this.property, defaultValue)`.';
+}
+
+module.exports = {
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'Use the `||` operator instead of `getWithDefault` for more expected behaviors',
+      category: 'Best Practices',
+      recommended: false,
+      octane: true,
+      url:
+        'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/no-get-with-default.md',
+    },
+  },
+  create(context) {
+    return {
+      CallExpression(node) {
+        if (
+          types.isMemberExpression(node.callee) &&
+          types.isThisExpression(node.callee.object) &&
+          types.isIdentifier(node.callee.property) &&
+          node.callee.property.name === 'getWithDefault' &&
+          node.arguments.length === 2
+        ) {
+          // Example: this.getWithDefault('foo', 'bar');
+          context.report(node, makeErrorMessageForGetWithDefault(node.arguments[0].value, false));
+        }
+
+        if (
+          types.isIdentifier(node.callee) &&
+          node.callee.name === 'getWithDefault' &&
+          node.arguments.length === 3 &&
+          types.isThisExpression(node.arguments[0])
+        ) {
+          // Example: getWithDefault(this, 'foo', 'bar');
+          context.report(node, makeErrorMessageForGetWithDefault(node.arguments[1].value, true));
+        }
+      },
+    };
+  },
+};

tests/lib/rules/no-get-with-default.js

@@ -0,0 +1,41 @@
+const rule = require('../../../lib/rules/no-get-with-default');
+const RuleTester = require('eslint').RuleTester;
+
+const ruleTester = new RuleTester({
+  parserOptions: {
+    ecmaVersion: 2015,
+    sourceType: 'module',
+  },
+});
+
+ruleTester.run('no-get-with-default', rule, {
+  valid: [
+    "const test = this.get('key') || [];",
+    "const test = get(this, 'target') || [];",
+    "testClass.getWithDefault('key', [])",
+    "getWithDefault.testMethod(testClass, 'key', [])",
+  ],
+  invalid: [
+    {
+      code: "const test = this.getWithDefault('key', []);",
+      errors: [
+        {
+          message:
+            'Use `this.property || defaultValue` or the `this.property === undefined ? defaultValue : this.property` instead of `getWithDefault(this.property, defaultValue)`.',
+          type: 'CallExpression',
+        },
+      ],
+      output: null,
+    },
+    {
+      code: "const test = getWithDefault(this, 'key', []);",
+      errors: [
+        {
+          message: 'Use `||` or the ternary operator instead of `getWithDefault()`.',
+          type: 'CallExpression',
+        },
+      ],
+      output: null,
+    },
+  ],
+});