Use `let_it_be` for set up

spec/finders/todos_finder_spec.rb

@@ -4,14 +4,14 @@ require 'spec_helper'
 
 RSpec.describe TodosFinder do
   describe '#execute' do
-    let(:user) { create(:user) }
-    let(:group) { create(:group) }
-    let(:project) { create(:project, namespace: group) }
-    let(:issue) { create(:issue, project: project) }
-    let(:merge_request) { create(:merge_request, source_project: project) }
+    let_it_be(:user) { create(:user) }
+    let_it_be(:group) { create(:group) }
+    let_it_be(:project) { create(:project, :repository, namespace: group) }
+    let_it_be(:issue) { create(:issue, project: project) }
+    let_it_be(:merge_request) { create(:merge_request, source_project: project) }
     let(:finder) { described_class }
 
-    before do
+    before_all do
       group.add_developer(user)
     end
 
@@ -89,8 +89,6 @@ RSpec.describe TodosFinder do
           end
 
           it 'raises an argument error when invalid type is passed' do
-            create(:todo, user: user, group: group, target: create(:design))
-
             todos_finder = finder.new(user, { type: %w[Issue MergeRequest NotAValidType] })
 
             expect { todos_finder.execute }.to raise_error(ArgumentError)
@@ -131,8 +129,8 @@ RSpec.describe TodosFinder do
         end
 
         context 'when filtering by author' do
-          let(:author1) { create(:user) }
-          let(:author2) { create(:user) }
+          let_it_be(:author1) { create(:user) }
+          let_it_be(:author2) { create(:user) }
 
           let!(:todo1) { create(:todo, user: user, author: author1) }
           let!(:todo2) { create(:todo, user: user, author: author2) }
@@ -154,7 +152,7 @@ RSpec.describe TodosFinder do
 
         context 'by groups' do
           context 'with subgroups' do
-            let(:subgroup) { create(:group, parent: group) }
+            let_it_be(:subgroup) { create(:group, parent: group) }
             let!(:todo3) { create(:todo, user: user, group: subgroup, target: issue) }
 
             it 'returns todos from subgroups when filtered by a group' do
@@ -167,17 +165,14 @@ RSpec.describe TodosFinder do
           context 'filtering for multiple groups' do
             let_it_be(:group2) { create(:group) }
             let_it_be(:group3) { create(:group) }
+            let_it_be(:subgroup1) { create(:group, parent: group) }
+            let_it_be(:subgroup2) { create(:group, parent: group2) }
 
             let!(:todo1) { create(:todo, user: user, project: project, target: issue) }
             let!(:todo2) { create(:todo, user: user, group: group, target: merge_request) }
             let!(:todo3) { create(:todo, user: user, group: group2, target: merge_request) }
-
-            let(:subgroup1) { create(:group, parent: group) }
             let!(:todo4) { create(:todo, user: user, group: subgroup1, target: issue) }
-
-            let(:subgroup2) { create(:group, parent: group2) }
             let!(:todo5) { create(:todo, user: user, group: subgroup2, target: issue) }
-
             let!(:todo6) { create(:todo, user: user, group: group3, target: issue) }
 
             it 'returns the expected groups' do