Fix orphaned objects deletion bug (#15657)

* Fix orphaned objects deletion bug

* extend test

Co-authored-by: 6543 <6543@obermui.de>

models/consistency_test.go

@@ -0,0 +1,32 @@
+// Copyright 2021 Gitea. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package models
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestDeleteOrphanedObjects(t *testing.T) {
+	assert.NoError(t, PrepareTestDatabase())
+
+	countBefore, err := x.Count(&PullRequest{})
+	assert.NoError(t, err)
+
+	_, err = x.Insert(&PullRequest{IssueID: 1000}, &PullRequest{IssueID: 1001}, &PullRequest{IssueID: 1003})
+	assert.NoError(t, err)
+
+	orphaned, err := CountOrphanedObjects("pull_request", "issue", "pull_request.issue_id=issue.id")
+	assert.NoError(t, err)
+	assert.EqualValues(t, 3, orphaned)
+
+	err = DeleteOrphanedObjects("pull_request", "issue", "pull_request.issue_id=issue.id")
+	assert.NoError(t, err)
+
+	countAfter, err := x.Count(&PullRequest{})
+	assert.NoError(t, err)
+	assert.EqualValues(t, countBefore, countAfter)
+}