feat(eslint-plugin): add sort-interface-members rule

packages/eslint-plugin/src/rules/sort-interface-members.ts

@@ -0,0 +1,53 @@
+/**
+ * @fileoverview Forbids unsorted interface members
+ */
+
+import { TSESTree } from '../../../typescript-estree/dist/parser';
+import * as util from '../util';
+import {
+  Identifier,
+  TSPropertySignature
+} from '@typescript-eslint/typescript-estree/dist/ts-estree/ts-estree';
+
+type Options = [];
+type MessageIds = 'notSorted';
+
+export default util.createRule<Options, MessageIds>({
+  name: 'sort-interface-members',
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'Forbids unsorted interface members',
+      category: 'Stylistic Issues',
+      recommended: false
+    },
+    schema: [],
+    messages: {
+      notSorted: 'The interface members are not sorted alphabetically.'
+    }
+  },
+  defaultOptions: [],
+  create(context) {
+    return {
+      TSInterfaceBody(node: TSESTree.TSInterfaceBody) {
+        const members = node.body as TSPropertySignature[];
+
+        for (let i = 0; i < members.length - 1; i++) {
+          const currentItemKey = members[i].key as Identifier;
+          const nextItemKey = members[i + 1].key as Identifier;
+
+          if (currentItemKey.name > nextItemKey.name) {
+            context.report({
+              messageId: 'notSorted',
+              node: currentItemKey
+            });
+
+            return; // Leave loop immediately
+          }
+        }
+
+        return; // No rule violation found
+      }
+    };
+  }
+});

packages/eslint-plugin/tests/rules/sort-interface-members.test.ts

@@ -0,0 +1,54 @@
+import { RuleTester } from '../RuleTester';
+import rule from '../../src/rules/sort-interface-members';
+
+const ruleTester = new RuleTester({
+  parser: '@typescript-eslint/parser'
+});
+
+ruleTester.run('sort-interface-members', rule, {
+  valid: [
+    `
+interface Foo {
+    A: string;
+    B: string;
+    C: string;
+}
+    `,
+    `
+interface Foo {
+    A(): void;
+    B: string;
+    C: string;
+}
+    `
+  ],
+  invalid: [
+    {
+      code: `
+interface Foo {
+    C: string;
+    B: string;
+    A: string;
+}
+    `,
+      errors: [
+        {
+          messageId: 'notSorted'
+        }
+      ]
+    },
+    {
+      code: `
+interface Foo {
+    a: string;
+    A: string;
+}
+    `,
+      errors: [
+        {
+          messageId: 'notSorted'
+        }
+      ]
+    }
+  ]
+});