refac: article title rules are the same in the API request and the domain; an invalid title returns 400 instead of 500

test/article_test.go

@@ -12,10 +12,11 @@ import (
 )
 
 type mockArticleRepo struct {
-	articles map[uint32]article.Article
-	images   map[uint32]*imageDomain.Image
-	nextID   uint32
-	fail     failSwitch
+	articles     map[uint32]article.Article
+	images       map[uint32]*imageDomain.Image
+	nextID       uint32
+	fail         failSwitch
+	createCalled bool
 }
 
 func newMockArticleRepo() *mockArticleRepo {
@@ -82,6 +83,7 @@ func (m *mockArticleRepo) GetAll() []article.Article {
 }
 
 func (m *mockArticleRepo) Create(a article.Article) (article.Article, error) {
+	m.createCalled = true
 	if err := m.fail.trigger("Create"); err != nil {
 		return article.Article{}, err
 	}