Fix #48537 - Update avatar only via the projects API

changelogs/unreleased/48537-update-avatar-only-via-api.yml

+---
+title: Allow updating a project's avatar without other params
+merge_request:
+author: Jamie Schembri
+type: fixed

lib/api/projects.rb

@@ -260,7 +260,8 @@ module API
             :snippets_enabled,
             :tag_list,
             :visibility,
-            :wiki_enabled
+            :wiki_enabled,
+            :avatar
           ]
         optional :name, type: String, desc: 'The name of the project'
         optional :default_branch, type: String, desc: 'The default branch of the project'

spec/requests/api/projects_spec.rb

@@ -1526,6 +1526,20 @@ describe API::Projects do
 
         expect(response).to have_gitlab_http_status(400)
       end
+
+      it 'updates avatar' do
+        project_param = {
+          avatar: fixture_file_upload('spec/fixtures/banana_sample.gif',
+                                      'image/gif')
+        }
+
+        put api("/projects/#{project3.id}", user), project_param
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(json_response['avatar_url']).to eq('http://localhost/uploads/'\
+                                                  '-/system/project/avatar/'\
+                                                  "#{project3.id}/banana_sample.gif")
+      end
     end
 
     context 'when authenticated as project master' do