[TESTS] auth LinkAccount test coverage

(cherry picked from commit e11dcc60f2)

use backticks to avoid backslash

(cherry picked from commit 34212791ee)
(cherry picked from commit bde9473c69)
(cherry picked from commit d4deb43084)
(cherry picked from commit 08e91649b0)
(cherry picked from commit 2b988e5415)

[TESTS] auth LinkAccount test coverage (squash)

(cherry picked from commit a2b2e3066b)
(cherry picked from commit 841d1b5073)
(cherry picked from commit 35da630ad8)

models/auth/source.go

@@ -5,6 +5,7 @@
 package auth
 
 import (
+	"context"
 	"fmt"
 	"reflect"
 
@@ -306,6 +307,17 @@ func GetSourceByID(id int64) (*Source, error) {
 	return source, nil
 }
 
+func GetSourceByName(ctx context.Context, name string) (*Source, error) {
+	source := &Source{}
+	has, err := db.GetEngine(ctx).Where("name = ?", name).Get(source)
+	if err != nil {
+		return nil, err
+	} else if !has {
+		return nil, ErrSourceNotExist{}
+	}
+	return source, nil
+}
+
 // UpdateSource updates a Source record in DB.
 func UpdateSource(source *Source) error {
 	var originalSource *Source