Set indexConfig.SpecAbsolutePath to "root.yaml" (theoretical root) wh…

…en the spec's root does not exist on the filesystem (either read from remote URL or []byte)

bundler/bundler_test.go

@@ -38,6 +38,7 @@ func TestBundleDocument_DigitalOcean(t *testing.T) {
 	digi, _ := os.ReadFile(spec)
 
 	doc, err := libopenapi.NewDocumentWithConfiguration([]byte(digi), &datamodel.DocumentConfiguration{
+		SpecFilePath:            spec,
 		BasePath:                tmp + "/specification",
 		ExtractRefsSequentially: true,
 		Logger: slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{

index/rolodex.go

@@ -313,7 +313,13 @@ func (r *Rolodex) IndexTheRolodex() error {
 			}
 
 			if len(r.localFS) > 0 || len(r.remoteFS) > 0 {
-				r.indexConfig.SpecAbsolutePath = filepath.Join(basePath, filepath.Base(r.indexConfig.SpecFilePath))
+				// For specs that are not read from a filesystem (either from remote URL or []byte), we need to
+				// assign a theoretical root file. Having a root file is necessary when mapping references.
+				rootFile := "root.yaml"
+				if r.indexConfig.SpecFilePath != "" {
+					rootFile = filepath.Base(r.indexConfig.SpecFilePath)
+				}
+				r.indexConfig.SpecAbsolutePath = filepath.Join(basePath, rootFile)
 			}
 		}