Apply Rails/SaveBang rubocop rule

Having exceptions is better than having silent bugs.

There are a few methods I've kept the same way they were.

The `RelatedContentScore#score_with_opposite` method is a bit peculiar:
it creates scores for both itself and the opposite related content,
which means the opposite related content will try to create the same
scores as well.

We've already got a test to check `Budget::Ballot#add_investment` when
creating a line fails ("Edge case voting a non-elegible investment").

Finally, the method `User#send_oauth_confirmation_instructions` doesn't
update the record when the email address isn't already present, leading
to the test "Try to register with the email of an already existing user,
when an unconfirmed email was provided by oauth" fo fail if we raise an
exception for an invalid user. That's because updating a user's email
doesn't update the database automatically, but instead a confirmation
email is sent.

There are also a few false positives for classes which don't have bang
methods (like the GraphQL classes) or destroying attachments.

For these reasons, I'm adding the rule with a "Refactor" severity,
meaning it's a rule we can break if necessary.

spec/shared/models/acts_as_imageable.rb

@@ -67,7 +67,7 @@ shared_examples "acts as imageable" do |imageable_factory|
   end
 
   it "image destroy should remove image from file storage" do
-    image.save
+    image.save!
     image_url = image.attachment.url
     new_url = "/attachments/original/missing.png"
 

spec/shared/models/acts_as_paranoid.rb

@@ -2,7 +2,7 @@ shared_examples "acts as paranoid" do |factory_name|
   let!(:resource) { create(factory_name) }
 
   it "#{described_class} can be recovered after soft deletion" do
-    resource.destroy
+    resource.destroy!
     resource.reload
 
     expect(resource.hidden_at).not_to be_blank
@@ -15,7 +15,7 @@ shared_examples "acts as paranoid" do |factory_name|
   describe "#{described_class} translations" do
 
     it "is hidden after parent resource destroy" do
-      resource.destroy
+      resource.destroy!
       resource.reload
 
       expect(resource.translations.with_deleted.first.hidden_at).not_to be_blank
@@ -26,16 +26,16 @@ shared_examples "acts as paranoid" do |factory_name|
     end
 
     it "cannot be recovered through non recursive restore" do
-      resource.destroy
+      resource.destroy!
       resource.reload
 
       expect { resource.restore }.not_to change { resource.translations.with_deleted.first.hidden_at }
     end
 
     it "can be recovered through recursive restore after non-recursive restore" do
-      resource.destroy
+      resource.destroy!
       resource.restore
-      resource.destroy
+      resource.destroy!
       resource.reload
 
       expect { resource.restore(recursive: true) }.to change { resource.translations.with_deleted.first.hidden_at }
@@ -48,10 +48,10 @@ shared_examples "acts as paranoid" do |factory_name|
         new_translation.send("#{translated_attribute_name}=", original_translation.send(translated_attribute_name))
       end
       new_translation.locale = :fr
-      new_translation.save
+      new_translation.save!
 
       expect(resource.translations.with_deleted.count).to eq(2)
-      resource.destroy
+      resource.destroy!
       resource.reload
       expect(resource.translations.with_deleted.count).to eq(2)
       expect(resource.translations.with_deleted.first.hidden_at).not_to be_blank

spec/shared/models/document_validations.rb

@@ -47,14 +47,14 @@ shared_examples "document validations" do |documentable_factory|
   end
 
   it "is not valid without a documentable_id" do
-    document.save
+    document.save!
     document.documentable_id = nil
 
     expect(document).not_to be_valid
   end
 
   it "is not valid without a documentable_type" do
-    document.save
+    document.save!
     document.documentable_type = nil
 
     expect(document).not_to be_valid

spec/shared/models/image_validations.rb

@@ -55,14 +55,14 @@ shared_examples "image validations" do |imageable_factory|
   end
 
   it "is not valid without a imageable_id" do
-    image.save
+    image.save!
     image.imageable_id = nil
 
     expect(image).not_to be_valid
   end
 
   it "is not valid without a imageable_type" do
-    image.save
+    image.save!
     image.imageable_type = nil
 
     expect(image).not_to be_valid

spec/shared/models/map_validations.rb

@@ -51,7 +51,7 @@ shared_examples "map validations" do
     it "expires cache when the map is updated" do
       map_location = create(:map_location)
       mappable.map_location = map_location
-      mappable.save
+      mappable.save!
 
       expect { map_location.update(latitude: 12.34) }
         .to change { mappable.reload.updated_at }

spec/shared/models/notifiable.rb

@@ -78,7 +78,7 @@ shared_examples "notifiable" do
       notification = create(:notification, notifiable: notifiable)
 
       if notifiable.respond_to?(:retired_at)
-        notifiable.update(retired_at: Time.current, retired_reason: "unfeasible",
+        notifiable.update!(retired_at: Time.current, retired_reason: "unfeasible",
           retired_explanation: "Unfeasibility explanation ...")
         expect(notification.check_availability(notifiable)).to be(false)
       end