fix: parameters defined as a reference in the path-params-defined rule

Author: DmitryAnansky

.changeset/evil-states-fold.md

@@ -0,0 +1,5 @@
+---
+"@redocly/openapi-core": patch
+---
+
+Fixed `path-params-defined` rule to correctly skip parameters defined via `$ref`.

packages/core/src/rules/common/__tests__/path-params-defined.test.ts

@@ -402,4 +402,30 @@ describe('Oas3 path-params-defined', () => {
       ]
     `);
   });
+
+  it('should not report on undefined params in case of reference', async () => {
+    const document = parseYamlToDocument(
+      outdent`
+        openapi: 3.0.0
+        paths:
+          /test-endpoint:
+            get:
+              operationId: testEndpoint
+              tags:
+                - Test
+              summary: Test endpoint to reproduce bug
+              parameters:
+                $ref: ./test_params.yaml
+      `,
+      'foobar.yaml'
+    );
+
+    const results = await lintDocument({
+      externalRefResolver: new BaseResolver(),
+      document,
+      config: await createConfig({ rules: { 'path-params-defined': 'error' } }),
+    });
+
+    expect(replaceSourceWithRef(results)).toMatchInlineSnapshot(`[]`);
+  });
 });

packages/core/src/rules/common/path-params-defined.ts

@@ -151,12 +151,19 @@ const extractTemplateParams = (path: string): Set<string> => {
 };
 
 const collectPathParamsFromOperation = (operation: unknown, targetSet: Set<string>): void => {
-  const op = operation as { parameters?: Array<{ in?: string; name?: string }> };
-  op?.parameters?.forEach((param) => {
-    if (param?.in === 'path' && param?.name) {
-      targetSet.add(param.name);
+  const op = operation as { parameters?: unknown };
+  const params = op?.parameters;
+
+  if (Array.isArray(params)) {
+    for (const param of params) {
+      if (param && typeof param === 'object' && 'in' in param && 'name' in param) {
+        const p = param as { in?: string; name?: string };
+        if (p.in === 'path' && p.name) {
+          targetSet.add(p.name);
+        }
+      }
     }
-  });
+  }
 };
 
 const validatePathParameter = (