Fixed last commit widget not showing with Gravatar disabled

Closes https://gitlab.com/gitlab-org/gitlab/issues/207723

app/graphql/types/user_type.rb

@@ -14,7 +14,7 @@ module Types
           description: 'Human-readable name of the user'
     field :username, GraphQL::STRING_TYPE, null: false,
           description: 'Username of the user. Unique within this instance of GitLab'
-    field :avatar_url, GraphQL::STRING_TYPE, null: false,
+    field :avatar_url, GraphQL::STRING_TYPE, null: true,
           description: "URL of the user's avatar"
     field :web_url, GraphQL::STRING_TYPE, null: false,
           description: 'Web URL of the user'

changelogs/unreleased/ph-207723-userTypeGravatarDisabled.yml

+---
+title: Fixed last commit widget when Gravatar is disabled
+merge_request:
+author:
+type: fixed

doc/api/graphql/reference/gitlab_schema.graphql

@@ -8003,7 +8003,7 @@ type User {
   """
   URL of the user's avatar
   """
-  avatarUrl: String!
+  avatarUrl: String
 
   """
   Human-readable name of the user

doc/api/graphql/reference/gitlab_schema.json

@@ -6171,13 +6171,9 @@
 
               ],
               "type": {
-                "kind": "NON_NULL",
-                "name": null,
-                "ofType": {
                 "kind": "SCALAR",
                 "name": "String",
                 "ofType": null
-                }
               },
               "isDeprecated": false,
               "deprecationReason": null

doc/api/graphql/reference/index.md

@@ -1287,7 +1287,7 @@ Autogenerated return type of UpdateSnippet
 
 | Name  | Type  | Description |
 | ---   |  ---- | ----------  |
-| `avatarUrl` | String! | URL of the user's avatar |
+| `avatarUrl` | String | URL of the user's avatar |
 | `name` | String! | Human-readable name of the user |
 | `userPermissions` | UserPermissions! | Permissions for the current user on the resource |
 | `username` | String! | Username of the user. Unique within this instance of GitLab |

spec/features/projects/tree/tree_show_spec.rb

@@ -5,11 +5,14 @@ require 'spec_helper'
 describe 'Projects tree', :js do
   let(:user) { create(:user) }
   let(:project) { create(:project, :repository) }
+  let(:gravatar_enabled) { true }
 
   # This commit has a known state on the master branch of gitlab-test
   let(:test_sha) { '7975be0116940bf2ad4321f79d02a55c5f7779aa' }
 
   before do
+    stub_application_setting(gravatar_enabled: gravatar_enabled)
+
     project.add_maintainer(user)
     sign_in(user)
   end
@@ -34,6 +37,20 @@ describe 'Projects tree', :js do
     expect(page).not_to have_selector('.flash-alert')
   end
 
+  context 'gravatar disabled' do
+    let(:gravatar_enabled) { false }
+
+    it 'renders last commit' do
+      visit project_tree_path(project, test_sha)
+      wait_for_requests
+
+      page.within('.project-last-commit') do
+        expect(page).to have_selector('.user-avatar-link')
+        expect(page).to have_content('Merge branch')
+      end
+    end
+  end
+
   context 'for signed commit' do
     it 'displays a GPG badge' do
       visit project_tree_path(project, '33f3729a45c02fc67d00adb1b8bca394b0e761d9')