test(avatar): deleting a user avatar and file is atomic

The avatar must not be unset in the database if there is a failure to
remove the avatar file from storage (file or S3). The two operations
are wrapped in a transaction for that purpose and this test verifies
it is effective.

See 1be797faba Fix bug on avatar

services/user/avatar_test.go

@@ -0,0 +1,47 @@
+// Copyright The Forgejo Authors.
+// SPDX-License-Identifier: MIT
+
+package user
+
+import (
+	"bytes"
+	"image"
+	"image/png"
+	"testing"
+
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/unittest"
+	user_model "code.gitea.io/gitea/models/user"
+	"code.gitea.io/gitea/modules/storage"
+	"code.gitea.io/gitea/modules/test"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestUserDeleteAvatar(t *testing.T) {
+	myImage := image.NewRGBA(image.Rect(0, 0, 1, 1))
+	var buff bytes.Buffer
+	png.Encode(&buff, myImage)
+
+	assert.NoError(t, unittest.PrepareTestDatabase())
+	user := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+
+	err := UploadAvatar(db.DefaultContext, user, buff.Bytes())
+	assert.NoError(t, err)
+	verification := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+	assert.NotEqual(t, "", verification.Avatar)
+
+	t.Run("AtomicStorageFailure", func(t *testing.T) {
+		defer test.MockVariableValue[storage.ObjectStorage](&storage.Avatars, storage.UninitializedStorage)()
+		err = DeleteAvatar(db.DefaultContext, user)
+		assert.Error(t, err)
+		verification := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+		assert.True(t, verification.UseCustomAvatar)
+	})
+
+	err = DeleteAvatar(db.DefaultContext, user)
+	assert.NoError(t, err)
+
+	verification = unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
+	assert.Equal(t, "", verification.Avatar)
+}