You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: delete_reference_image_test.go
    path of file: ./repos/golang-samples/vision/product_search
    
    the code of the file until where you have to start completion: // Copyright 2019 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package productsearch

import (
	"bytes"
	"strings"
	"testing"

	"github.com/GoogleCloudPlatform/golang-samples/internal/testutil"
)

func TestDeleteReferenceImage(t *testing.T) {
	tc := testutil.SystemTest(t)

	const location = "us-west1"
	const productDisplayName = "fake_product_display_name_for_testing"
	const productCategory = "homegoods"
	const productID = "fake_product_id_for_testing"
	const referenceImageID = "fake
    
func TestDeleteReferenceImage(t *testing.T) {
	tc := testutil.SystemTest(t)

	const location = "us-west1"
	const productDisplayName = "fake_product_display_name_for_testing"
	const productCategory = "homegoods"
	const productID = "fake_product_id_for_testing"
	const referenceImageID = "fake_reference_image_id_for_testing"
	const gcsURI = "gs://cloud-samples-data/vision/product_search/shoes_1.jpg"

	var buf bytes.Buffer

	// Ensure re-used resource names don't exist prior to test start.
	if err := getReferenceImage(&buf, tc.ProjectID, location, productID, referenceImageID); err == nil {
		deleteReferenceImage(&buf, tc.ProjectID, location, productID, referenceImageID)
	}
	if err := getProduct(&buf, tc.ProjectID, location, productID); err == nil {
		deleteProduct(&buf, tc.ProjectID, location, productID)
	}
	buf.Reset()

	// Create a fake product.
	if err := createProduct(&buf, tc.ProjectID, location, productID, productDisplayName, productCategory); err != nil {
		t.Fatalf("createProduct: %v", err)
	}

	// Create reference image.
	if err := createReferenceImage(&buf, tc.ProjectID, location, productID, referenceImageID, gcsURI); err != nil {
		t.Fatalf("createReferenceImage: %v", err)
	}

	// Confirm the reference image exists.
	buf.Reset()
	if err := listReferenceImages(&buf, tc.ProjectID, location, productID); err != nil {
		t.Fatalf("listReferenceImages: %v", err)
	}
	if got := buf.String(); !strings.Contains(got, referenceImageID) {
		t.Errorf("Reference image ID %s does not exist", referenceImageID)
	}

	// Delete reference image.
	if err := deleteReferenceImage(&buf, tc.ProjectID, location, productID, referenceImageID); err != nil {
		t.Fatalf("deleteReferenceImage: %v", err)
	}

	// Check if the reference image is deleted.
	buf.Reset()
	if err := listReferenceImages(&buf, tc.ProjectID, location, productID); err != nil {
		t.Fatalf("listReferenceImages: %v", err)
	}
	if got := buf.String(); strings.Contains(got, referenceImageID) {
		t.Errorf("Reference image ID %s still exists", referenceImageID)
	}

	// Clean up.
	deleteProduct(&buf, tc.ProjectID, location, productID)
}