chore: Remove GetTopicByName

- Introduced in bec69f702b and removed in
the same commit (only usage was in testing code).

.deadcode-out

@@ -67,10 +67,6 @@ code.gitea.io/gitea/models/project
 code.gitea.io/gitea/models/repo
 	DeleteAttachmentsByIssue
 	FindReposMapByIDs
-	IsErrTopicNotExist
-	ErrTopicNotExist.Error
-	ErrTopicNotExist.Unwrap
-	GetTopicByName
 	WatchRepoMode
 
 code.gitea.io/gitea/models/user

models/repo/topic.go

@@ -5,14 +5,12 @@ package repo
 
 import (
 	"context"
-	"fmt"
 	"regexp"
 	"strings"
 
 	"code.gitea.io/gitea/models/db"
 	"code.gitea.io/gitea/modules/container"
 	"code.gitea.io/gitea/modules/timeutil"
-	"code.gitea.io/gitea/modules/util"
 
 	"xorm.io/builder"
 )
@@ -39,26 +37,6 @@ type RepoTopic struct { //revive:disable-line:exported
 	TopicID int64 `xorm:"pk"`
 }
 
-// ErrTopicNotExist represents an error that a topic is not exist
-type ErrTopicNotExist struct {
-	Name string
-}
-
-// IsErrTopicNotExist checks if an error is an ErrTopicNotExist.
-func IsErrTopicNotExist(err error) bool {
-	_, ok := err.(ErrTopicNotExist)
-	return ok
-}
-
-// Error implements error interface
-func (err ErrTopicNotExist) Error() string {
-	return fmt.Sprintf("topic is not exist [name: %s]", err.Name)
-}
-
-func (err ErrTopicNotExist) Unwrap() error {
-	return util.ErrNotExist
-}
-
 // ValidateTopic checks a topic by length and match pattern rules
 func ValidateTopic(topic string) bool {
 	return len(topic) <= 35 && topicPattern.MatchString(topic)
@@ -91,17 +69,6 @@ func SanitizeAndValidateTopics(topics []string) (validTopics, invalidTopics []st
 	return validTopics, invalidTopics
 }
 
-// GetTopicByName retrieves topic by name
-func GetTopicByName(ctx context.Context, name string) (*Topic, error) {
-	var topic Topic
-	if has, err := db.GetEngine(ctx).Where("name = ?", name).Get(&topic); err != nil {
-		return nil, err
-	} else if !has {
-		return nil, ErrTopicNotExist{name}
-	}
-	return &topic, nil
-}
-
 // addTopicByNameToRepo adds a topic name to a repo and increments the topic count.
 // Returns topic after the addition
 func addTopicByNameToRepo(ctx context.Context, repoID int64, topicName string) (*Topic, error) {

models/repo/topic_test.go

@@ -52,8 +52,7 @@ func TestAddTopic(t *testing.T) {
 	require.NoError(t, repo_model.SaveTopics(db.DefaultContext, 2, "golang", "gitea"))
 	repo2NrOfTopics = 2
 	totalNrOfTopics++
-	topic, err := repo_model.GetTopicByName(db.DefaultContext, "gitea")
-	require.NoError(t, err)
+	topic := unittest.AssertExistsAndLoadBean(t, &repo_model.Topic{Name: "gitea"})
 	assert.EqualValues(t, 1, topic.RepoCount)
 
 	topics, _, err = repo_model.FindTopics(db.DefaultContext, &repo_model.FindTopicOptions{})