Merge pull request #2482 from NullVoxPopuli/nvp/template-lint-extract-rule-template-no-negated-comparison

Extract rule: template-no-negated-comparison

Author: NullVoxPopuli

README.md

@@ -210,6 +210,7 @@ rules in templates can be disabled with eslint directives with mustache or html
 | [template-no-input-placeholder](docs/rules/template-no-input-placeholder.md)                           | disallow placeholder attribute on input elements                        |    |    |    |
 | [template-no-input-tagname](docs/rules/template-no-input-tagname.md)                                   | disallow tagName attribute on {{input}} helper                          |    |    |    |
 | [template-no-log](docs/rules/template-no-log.md)                                                       | disallow {{log}} in templates                                           |    |    |    |
+| [template-no-negated-comparison](docs/rules/template-no-negated-comparison.md)                         | disallow negated comparisons in templates                               |    |    |    |
 | [template-no-negated-condition](docs/rules/template-no-negated-condition.md)                           | disallow negated conditions in if/unless                                |    |    |    |
 | [template-no-nested-splattributes](docs/rules/template-no-nested-splattributes.md)                     | disallow nested ...attributes usage                                     |    |    |    |
 | [template-no-obscure-array-access](docs/rules/template-no-obscure-array-access.md)                     | disallow obscure array access patterns like `objectPath.@each.property` |    |    |    |

docs/rules/template-no-negated-comparison.md

@@ -0,0 +1,51 @@
+# ember/template-no-negated-comparison
+
+<!-- end auto-generated rule header -->
+
+Disallows negated comparison operators in templates.
+
+## Rule Details
+
+Use positive comparison operators with `{{unless}}` instead of negated comparison operators like `not-eq` or `ne`.
+
+## Examples
+
+Examples of **incorrect** code for this rule:
+
+```gjs
+<template>
+  {{#if (not-eq this.value 5)}}
+    Not equal
+  {{/if}}
+</template>
+```
+
+```gjs
+<template>
+  {{#if (ne this.a this.b)}}
+    Not equal
+  {{/if}}
+</template>
+```
+
+Examples of **correct** code for this rule:
+
+```gjs
+<template>
+  {{#unless (eq this.value 5)}}
+    Not equal
+  {{/unless}}
+</template>
+```
+
+```gjs
+<template>
+  {{#if (eq this.value 5)}}
+    Equal
+  {{/if}}
+</template>
+```
+
+## References
+
+- [eslint-plugin-ember template-no-negated-condition](https://github.com/ember-cli/eslint-plugin-ember/blob/master/docs/rules/template-no-negated-condition.md)

lib/rules/template-no-negated-comparison.js

@@ -0,0 +1,34 @@
+/** @type {import('eslint').Rule.RuleModule} */
+module.exports = {
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'disallow negated comparisons in templates',
+      category: 'Best Practices',
+      url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/template-no-negated-comparison.md',
+      templateMode: 'both',
+    },
+    fixable: null,
+    schema: [],
+    messages: {
+      noNegatedComparison: 'Use positive comparison operators instead of negated ones.',
+    },
+  },
+
+  create(context) {
+    return {
+      GlimmerSubExpression(node) {
+        if (
+          node.path &&
+          node.path.type === 'GlimmerPathExpression' &&
+          (node.path.original === 'not-eq' || node.path.original === 'ne')
+        ) {
+          context.report({
+            node,
+            messageId: 'noNegatedComparison',
+          });
+        }
+      },
+    };
+  },
+};

tests/lib/rules/template-no-negated-comparison.js

@@ -0,0 +1,76 @@
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const rule = require('../../../lib/rules/template-no-negated-comparison');
+const RuleTester = require('eslint').RuleTester;
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+const ruleTester = new RuleTester({
+  parser: require.resolve('ember-eslint-parser'),
+  parserOptions: { ecmaVersion: 2022, sourceType: 'module' },
+});
+
+ruleTester.run('template-no-negated-comparison', rule, {
+  valid: [
+    `<template>
+      {{#if (eq this.value 5)}}
+        Equal
+      {{/if}}
+    </template>`,
+    `<template>
+      {{#unless (eq this.value 5)}}
+        Not equal
+      {{/unless}}
+    </template>`,
+    `<template>
+      <div></div>
+    </template>`,
+  ],
+
+  invalid: [
+    {
+      code: `<template>
+        {{#if (not-eq this.value 5)}}
+          Not equal
+        {{/if}}
+      </template>`,
+      output: null,
+      errors: [
+        {
+          message: 'Use positive comparison operators instead of negated ones.',
+          type: 'GlimmerSubExpression',
+        },
+      ],
+    },
+    {
+      code: `<template>
+        {{#if (ne this.a this.b)}}
+          Not equal
+        {{/if}}
+      </template>`,
+      output: null,
+      errors: [
+        {
+          message: 'Use positive comparison operators instead of negated ones.',
+          type: 'GlimmerSubExpression',
+        },
+      ],
+    },
+    {
+      code: `<template>
+        <div class={{if (not-eq this.state "active") "inactive"}}></div>
+      </template>`,
+      output: null,
+      errors: [
+        {
+          message: 'Use positive comparison operators instead of negated ones.',
+          type: 'GlimmerSubExpression',
+        },
+      ],
+    },
+  ],
+});