feat: add validation rules for tags to have unique name

packages/apidom-ls/src/config/codes.ts

@@ -791,6 +791,7 @@ enum ApilintCodes {
   OPENAPI2_TAG_FIELD_NAME_REQUIRED,
   OPENAPI2_TAG_FIELD_DESCRIPTION_TYPE = 3190200,
   OPENAPI2_TAG_FIELD_EXTERNAL_DOCS_TYPE = 3190300,
+  OPENAPI2_TAG_FIELD_UNIQUE_NAME_VALUE_TYPE = 3190400,
 
   OPENAPI2_XML = 3200000,
   OPENAPI2_XML_FIELD_NAME_TYPE = 3200100,

packages/apidom-ls/src/config/openapi/tag/documentation.ts

@@ -13,6 +13,16 @@ import { OpenAPI2, OpenAPI30, OpenAPI31, OpenAPI3 } from '../target-specs.ts';
 const documentation = [
   { target: 'name', docs: '**Required.** The name of the tag.', targetSpecs: OpenAPI2 },
   { target: 'name', docs: '**REQUIRED**. The name of the tag.', targetSpecs: OpenAPI3 },
+  {
+    target: 'name',
+    docs: 'Tag Objects must have unique `name` field values.',
+    targetSpecs: OpenAPI3,
+  },
+  {
+    target: 'name',
+    docs: 'Tag Objects must have unique `name` field values.',
+    targetSpecs: OpenAPI2,
+  },
   {
     target: 'description',
     docs: 'A short description for the tag. [GFM syntax](https://guides.github.com/features/mastering-markdown/#GitHub-flavored-markdown) can be used for rich text representation.',

packages/apidom-ls/src/config/openapi/tag/lint/index.ts

@@ -3,11 +3,13 @@ import nameTypeLint from './name--type.ts';
 import nameRequiredLint from './name--required.ts';
 import descriptionTypeLint from './description--type.ts';
 import externalDocsTypeLint from './external-docs--type.ts';
+import nameUniqueLint from './name--unique.ts';
 
 const lints = [
   allowedFieldsLint,
   nameTypeLint,
   nameRequiredLint,
+  nameUniqueLint,
   descriptionTypeLint,
   externalDocsTypeLint,
 ];

packages/apidom-ls/src/config/openapi/tag/lint/name--unique.ts

@@ -0,0 +1,21 @@
+import { DiagnosticSeverity } from 'vscode-languageserver-types';
+
+import ApilintCodes from '../../../codes.ts';
+import { LinterMeta } from '../../../../apidom-language-types.ts';
+import { OpenAPI2, OpenAPI3 } from '../../target-specs.ts';
+
+const nameUniqueLint: LinterMeta = {
+  code: ApilintCodes.OPENAPI2_TAG_FIELD_UNIQUE_NAME_VALUE_TYPE,
+  source: 'apilint',
+  message: 'Tag Objects must have unique `name` field values.',
+  severity: DiagnosticSeverity.Error,
+  linterFunction: 'apilintPropertyUniqueSiblingValue',
+  linterParams: ['tags', 'name'],
+  marker: 'value',
+  target: 'name',
+  markerTarget: 'name',
+  data: {},
+  targetSpecs: [...OpenAPI2, ...OpenAPI3],
+};
+
+export default nameUniqueLint;

packages/apidom-ls/src/services/validation/linter-functions.ts

@@ -795,6 +795,30 @@ export const standardLinterfunctions: FunctionItem[] = [
       return true;
     },
   },
+  {
+    functionName: 'apilintPropertyUniqueSiblingValue',
+    function: (element, elementOrClasses, key) => {
+      const value = toValue(element);
+
+      const filterSiblingsOAS2 = (
+        el: Element & { key?: { content?: string }; content: { value?: string } },
+      ) => isString(el) && el.key?.content === key && toValue(el.content.value) === value;
+
+      const filterSiblingsOAS3 = (el: Element) =>
+        isObject(el) && el.hasKey(key) && toValue(el.get(key)) === value;
+
+      const elements = filter((el: Element) => {
+        const classes: string[] = toValue(el.getMetaProperty('classes', []));
+
+        return (
+          (elementOrClasses.includes(el.element) ||
+            classes.every((v) => elementOrClasses.includes(v))) &&
+          (filterSiblingsOAS2(el) || filterSiblingsOAS3(el))
+        );
+      }, element.parent?.parent?.parent);
+      return elements.length <= 1;
+    },
+  },
   {
     functionName: 'apilintChannelParameterExist',
     function: (element: Element): boolean => {

packages/apidom-ls/test/fixtures/validation/oas/tags-unique-name.yaml

@@ -0,0 +1,18 @@
+openapi: 3.0.0
+info:
+  title: test
+  version: 1.0.12
+tags:
+  - name: pet
+    description: Everything about your Pets
+    externalDocs:
+      description: Find out more
+      url: http://swagger.io
+  - name: pet
+    description: Access to Petstore orders
+    externalDocs:
+      description: Find out more about our store
+      url: http://swagger.io
+  - name: user
+    description: Operations about user
+paths:

packages/apidom-ls/test/validate.ts

@@ -3788,4 +3788,40 @@ describe('apidom-ls-validate', function () {
 
     languageService.terminate();
   });
+
+  it('oas - tags name should have unique values', async function () {
+    const spec = fs
+      .readFileSync(path.join(__dirname, 'fixtures', 'validation', 'oas', 'tags-unique-name.yaml'))
+      .toString();
+    const doc: TextDocument = TextDocument.create(
+      'foo://bar/tags-unique-name.yaml',
+      'yaml',
+      0,
+      spec,
+    );
+    const languageService: LanguageService = getLanguageService(contextNoSchema);
+
+    const result = await languageService.doValidation(doc);
+    const expected: Diagnostic[] = [
+      {
+        message: 'Tag Objects must have unique `name` field values.',
+        severity: 1,
+        code: 3190400,
+        source: 'apilint',
+        data: {},
+        range: { start: { line: 5, character: 10 }, end: { line: 5, character: 13 } },
+      },
+      {
+        message: 'Tag Objects must have unique `name` field values.',
+        severity: 1,
+        code: 3190400,
+        source: 'apilint',
+        data: {},
+        range: { start: { line: 10, character: 10 }, end: { line: 10, character: 13 } },
+      },
+    ];
+    assert.deepEqual(result, expected);
+
+    languageService.terminate();
+  });
 });