refactor: prepare to decouple the "model migration" package and "models" package (#38533)

Migrations should never use model structs directly, because the model
structs can be different in different releases. e.g. if one migration uses
"User" model, it works in the early releases, then one day, when the
User model changes, the migration breaks because it will use the
new (incorrect) User model, it should only use the old User model.

The same to "modules/structs".

---------

Signed-off-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: delvh <dev.lh@web.de>

modelmigration/v1_22/v287_test.go

@@ -0,0 +1,57 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_22
+
+import (
+	"strconv"
+	"testing"
+
+	"gitea.dev/modelmigration/migrationtest"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_UpdateBadgeColName(t *testing.T) {
+	type Badge struct {
+		ID          int64 `xorm:"pk autoincr"`
+		Description string
+		ImageURL    string
+	}
+
+	// Prepare and load the testing database
+	x, deferable := migrationtest.PrepareTestEnv(t, 0, new(Badge))
+	defer deferable()
+	if x == nil || t.Failed() {
+		return
+	}
+
+	oldBadges := []*Badge{
+		{Description: "Test Badge 1", ImageURL: "https://example.com/badge1.png"},
+		{Description: "Test Badge 2", ImageURL: "https://example.com/badge2.png"},
+		{Description: "Test Badge 3", ImageURL: "https://example.com/badge3.png"},
+	}
+
+	for _, badge := range oldBadges {
+		_, err := x.Insert(badge)
+		assert.NoError(t, err)
+	}
+
+	if err := UseSlugInsteadOfIDForBadges(x); err != nil {
+		assert.NoError(t, err)
+		return
+	}
+
+	got := []BadgeUnique{}
+	if err := x.Table("badge").Asc("id").Find(&got); !assert.NoError(t, err) {
+		return
+	}
+
+	for i, e := range oldBadges {
+		got := got[i+1] // 1 is in the badge.yml
+		assert.Equal(t, e.ID, got.ID)
+		assert.Equal(t, strconv.FormatInt(e.ID, 10), got.Slug)
+	}
+
+	// TODO: check if badges have been updated
+}