fix: preserve object format dropdown options on /repo/create error (#4360)

To reproduce:
- make the repo creation form return with an error, like a duplicate name
- click on the Object format dropdown
- the options are missing as the listbox is empty

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/4360
Reviewed-by: Earl Warren <earl-warren@noreply.codeberg.org>
Co-authored-by: Solomon Victorino <git@solomonvictorino.com>
Co-committed-by: Solomon Victorino <git@solomonvictorino.com>

tests/integration/html_helper.go

@@ -5,6 +5,7 @@ package integration
 
 import (
 	"bytes"
+	"fmt"
 	"testing"
 
 	"github.com/PuerkitoBio/goquery"
@@ -36,6 +37,37 @@ func (doc *HTMLDoc) GetInputValueByName(name string) string {
 	return text
 }
 
+func (doc *HTMLDoc) AssertDropdown(t testing.TB, name string) *goquery.Selection {
+	t.Helper()
+
+	dropdownGroup := doc.Find(fmt.Sprintf(".dropdown:has(input[name='%s'])", name))
+	assert.Equal(t, dropdownGroup.Length(), 1, fmt.Sprintf("%s dropdown does not exist", name))
+	return dropdownGroup
+}
+
+// Assert that a dropdown has at least one non-empty option
+func (doc *HTMLDoc) AssertDropdownHasOptions(t testing.TB, dropdownName string) {
+	t.Helper()
+
+	options := doc.AssertDropdown(t, dropdownName).Find(".menu [data-value]:not([data-value=''])")
+	assert.Greater(t, options.Length(), 0, fmt.Sprintf("%s dropdown has no options", dropdownName))
+}
+
+func (doc *HTMLDoc) AssertDropdownHasSelectedOption(t testing.TB, dropdownName, expectedValue string) {
+	t.Helper()
+
+	dropdownGroup := doc.AssertDropdown(t, dropdownName)
+
+	selectedValue, _ := dropdownGroup.Find(fmt.Sprintf("input[name='%s']", dropdownName)).Attr("value")
+	assert.Equal(t, expectedValue, selectedValue, fmt.Sprintf("%s dropdown doesn't have expected value selected", dropdownName))
+
+	dropdownValues := dropdownGroup.Find(".menu [data-value]").Map(func(i int, s *goquery.Selection) string {
+		value, _ := s.Attr("data-value")
+		return value
+	})
+	assert.Contains(t, dropdownValues, expectedValue, fmt.Sprintf("%s dropdown doesn't have an option with expected value", dropdownName))
+}
+
 // Find gets the descendants of each element in the current set of
 // matched elements, filtered by a selector. It returns a new Selection
 // object containing these matched elements.