dossier: refactor piece_justificative specs

Use `eq` rather than `be` for integers.

spec/lib/active_storage/downloadable_file_spec.rb

@@ -13,7 +13,7 @@ describe ActiveStorage::DownloadableFile do
         dossier.champs << create(:champ, :piece_justificative, :with_piece_justificative_file)
       end
 
-      it { expect(list.length).to be 1 }
+      it { expect(list.length).to eq 1 }
     end
 
     context 'when there is a repetition bloc' do
@@ -21,7 +21,7 @@ describe ActiveStorage::DownloadableFile do
       let(:dossier) { create(:dossier, :en_construction, champs: [champ]) }
 
       it 'should have 4 piece_justificatives' do
-        expect(list.size).to eq(4)
+        expect(list.size).to eq 4
       end
     end
 
@@ -29,14 +29,14 @@ describe ActiveStorage::DownloadableFile do
       let(:commentaire) { create(:commentaire) }
       let(:dossier) { commentaire.dossier }
 
-      it { expect(list.length).to be 0 }
+      it { expect(list.length).to eq 0 }
     end
 
     context 'when there is a message with an attachment' do
       let(:commentaire) { create(:commentaire, :with_file) }
       let(:dossier) { commentaire.dossier }
 
-      it { expect(list.length).to be 1 }
+      it { expect(list.length).to eq 1 }
     end
   end
 end