diff --git a/gateway/assets/test/main.go b/gateway/assets/test/main.go
index d393c2a2d..3b955745b 100644
--- a/gateway/assets/test/main.go
+++ b/gateway/assets/test/main.go
@@ -5,15 +5,12 @@ import (
 	"html/template"
 	"net/http"
 	"net/url"
-	"os"
+	"strconv"
 
 	"github.com/ipfs/boxo/gateway/assets"
 )
 
 const (
-	directoryTemplateFile = "../directory-index.html"
-	dagTemplateFile       = "../dag-index.html"
-
 	testPath = "/ipfs/QmFooBarQXB2mzChmMeKY47C43LxUdg1NDJ5MWcKMKxDu7/a/b/c"
 )
 
@@ -67,60 +64,56 @@ var dagTestData = assets.DagTemplateData{
 	CodecHex:  "0x129",
 }
 
+var funcMap = template.FuncMap{
+	"iconFromExt": func(name string) string {
+		return "ipfs-_blank" // place-holder
+	},
+	"urlEscape": func(rawUrl string) string {
+		pathURL := url.URL{Path: rawUrl}
+		return pathURL.String()
+	},
+}
+
+func runTemplate(w http.ResponseWriter, filename string, data interface{}) {
+	tpl, err := template.New(filename).Funcs(funcMap).ParseFiles("../" + filename)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to parse template file: %s", err), http.StatusInternalServerError)
+		return
+	}
+	err = tpl.Execute(w, data)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to execute template: %s", err), http.StatusInternalServerError)
+		return
+	}
+}
+
 func main() {
 	mux := http.NewServeMux()
 	mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		switch r.URL.Path {
 		case "/dag":
-			dagTemplate, err := template.New("dag-index.html").ParseFiles(dagTemplateFile)
-			if err != nil {
-				http.Error(w, fmt.Sprintf("failed to parse template file: %s", err), http.StatusInternalServerError)
-				return
-			}
-			err = dagTemplate.Execute(w, &dagTestData)
-			if err != nil {
-				http.Error(w, fmt.Sprintf("failed to execute template: %s", err), http.StatusInternalServerError)
-				return
-			}
+			runTemplate(w, "dag-index.html", dagTestData)
 		case "/directory":
-			directoryTemplate, err := template.New("directory-index.html").Funcs(template.FuncMap{
-				"iconFromExt": func(name string) string {
-					return "ipfs-_blank" // place-holder
-				},
-				"urlEscape": func(rawUrl string) string {
-					pathURL := url.URL{Path: rawUrl}
-					return pathURL.String()
-				},
-			}).ParseFiles(directoryTemplateFile)
-			if err != nil {
-				http.Error(w, fmt.Sprintf("failed to parse template file: %s", err), http.StatusInternalServerError)
-				return
-			}
-			err = directoryTemplate.Execute(w, &directoryTestData)
+			runTemplate(w, "directory-index.html", directoryTestData)
+		case "/error":
+			statusCode, err := strconv.Atoi(r.URL.Query().Get("code"))
 			if err != nil {
-				http.Error(w, fmt.Sprintf("failed to execute template: %s", err), http.StatusInternalServerError)
-				return
+				statusCode = 500
 			}
+			runTemplate(w, "error.html", &assets.ErrorTemplateData{
+				Path:       "/ipfs/baguqeerabn4wonmz6icnk7dfckuizcsf4e4igua2ohdboecku225xxmujepa",
+				StatusCode: statusCode,
+				StatusText: http.StatusText(statusCode),
+				Error:      "this is just an example error",
+			})
 		case "/":
-			html := `<p>Test paths: <a href="/dag">DAG</a>, <a href="/directory">Directory</a>.`
+			html := `<p>Test paths: <a href="/dag">DAG</a>, <a href="/directory">Directory</a>, <a href="/error?code=500">Error</a>.`
 			_, _ = w.Write([]byte(html))
 		default:
 			http.Redirect(w, r, "/", http.StatusSeeOther)
 		}
 	})
 
-	if _, err := os.Stat(directoryTemplateFile); err != nil {
-		wd, _ := os.Getwd()
-		fmt.Printf("could not open template file %q, relative to %q: %s\n", directoryTemplateFile, wd, err)
-		os.Exit(1)
-	}
-
-	if _, err := os.Stat(dagTemplateFile); err != nil {
-		wd, _ := os.Getwd()
-		fmt.Printf("could not open template file %q, relative to %q: %s\n", dagTemplateFile, wd, err)
-		os.Exit(1)
-	}
-
-	fmt.Printf("listening on localhost:3000\n")
+	fmt.Printf("listening on http://localhost:3000/\n")
 	_ = http.ListenAndServe("localhost:3000", mux)
 }