openapi3: update TestIssue601 — lxkns.yaml has description siblings to $ref

lxkns.yaml is OAS 3.0.2 and uses `description` as a sibling to $ref in
many places, which is invalid in OAS 3.0 ($ref replaces the enclosing
object; siblings are ignored). Previously this was silently accepted
because validateExtras was only invoked on top-level component refs.
Now that nested SchemaRefs are validated too, those siblings surface
as a validation error and mask the example-type mismatch this test
actually targets.

Pass AllowExtraSiblingFields("description") so validation proceeds to
the example-type assertion the test was written for (same pattern
already used in issue513_test.go:264).

Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>

Author: reuvenharrison

openapi3/issue601_test.go

@@ -17,18 +17,20 @@ func TestIssue601(t *testing.T) {
 	doc, err := sl.LoadFromFile("testdata/lxkns.yaml")
 	require.NoError(t, err)
 
-	err = doc.Validate(sl.Context)
+	// lxkns.yaml has `description` siblings alongside $ref (invalid in OAS 3.0).
+	// Allow them so we can exercise the example-type validation this test actually targets.
+	err = doc.Validate(sl.Context, AllowExtraSiblingFields("description"))
 	require.ErrorContains(t, err, `invalid components: schema "DiscoveryResult": invalid example: Error at "/type": property "type" is missing`)
 	require.ErrorContains(t, err, `| Error at "/nsid": property "nsid" is missing`)
 
-	err = doc.Validate(sl.Context, DisableExamplesValidation())
+	err = doc.Validate(sl.Context, AllowExtraSiblingFields("description"), DisableExamplesValidation())
 	require.NoError(t, err)
 
 	// Now let's remove all the invalid parts
 	for _, schema := range doc.Components.Schemas {
 		schema.Value.Example = nil
 	}
 
-	err = doc.Validate(sl.Context)
+	err = doc.Validate(sl.Context, AllowExtraSiblingFields("description"))
 	require.NoError(t, err)
 }