refac: atomic merge, lost-update race, RunPurge cost, duplicated walks

test/article_test.go

@@ -25,6 +25,8 @@ type mockArticleRepo struct {
 	authors           *mockAuthorRepo
 	reportSlugRace    bool
 	createAlwaysRaces bool
+	afterFindByBody   func()
+	updateBodyIDs     []uint32
 }
 
 func newMockArticleRepo() *mockArticleRepo {
@@ -315,6 +317,7 @@ func (m *mockArticleRepo) Create(a article.Article) (article.Article, error) {
 }
 
 func (m *mockArticleRepo) UpdateBody(id uint32, body string) (article.Article, error) {
+	m.updateBodyIDs = append(m.updateBodyIDs, id)
 	if err := m.fail.trigger("UpdateBody"); err != nil {
 		return article.Article{}, err
 	}
@@ -427,6 +430,9 @@ func (m *mockArticleRepo) FindByBodyContaining(filename string) ([]article.Artic
 			result = append(result, a)
 		}
 	}
+	if m.afterFindByBody != nil {
+		defer m.afterFindByBody()
+	}
 	return result, nil
 }