Rails5 fix NoMethodError: undefined method 'message' for nil:NilClass

ee/changelogs/unreleased/rails5-fix-6605.yml

+---
+title: 'Rails5 fix NoMethodError: undefined method ''message'' for nil:NilClass'
+merge_request: 6507
+author: Jasper Maes
+type: fixed

ee/spec/lib/gitlab/database/load_balancing/load_balancer_spec.rb

@@ -12,6 +12,41 @@ describe Gitlab::Database::LoadBalancing::LoadBalancer do
     RequestStore.delete(described_class::CACHE_KEY)
   end
 
+  def raise_and_wrap(wrapper, original)
+    raise original
+  rescue original.class
+    raise wrapper.new('boop')
+  end
+
+  def wrapped_exception(wrapper, original)
+    if Gitlab.rails5?
+      begin
+        raise_and_wrap(wrapper, original.new)
+      rescue wrapper => error
+        error
+      end
+    else
+      wrapper.new('boop', original.new)
+    end
+  end
+
+  def twice_wrapped_exception(top, middle, original)
+    if Gitlab.rails5?
+      begin
+        begin
+          raise_and_wrap(middle, original.new)
+        rescue middle => middle_error
+          raise_and_wrap(top, middle_error)
+        end
+      rescue top => top_error
+        top_error
+      end
+    else
+      middle_error = middle.new('boop', original.new)
+      top.new('boop', middle_error)
+    end
+  end
+
   describe '#read' do
     let(:conflict_error) { Class.new(RuntimeError) }
 
@@ -227,23 +262,19 @@ describe Gitlab::Database::LoadBalancing::LoadBalancer do
     end
 
     it 'returns true for a wrapped connection error' do
-      original = NotImplementedError.new
-      wrapped = ActiveRecord::StatementInvalid.new('boop', original)
+      wrapped = wrapped_exception(ActiveRecord::StatementInvalid, NotImplementedError)
 
       expect(lb.connection_error?(wrapped)).to eq(true)
     end
 
     it 'returns true for a wrapped connection error from a view' do
-      original = NotImplementedError.new
-      wrapped = ActionView::Template::Error.new('boop', original)
+      wrapped = wrapped_exception(ActionView::Template::Error, NotImplementedError)
 
       expect(lb.connection_error?(wrapped)).to eq(true)
     end
 
     it 'returns true for deeply wrapped/nested errors' do
-      original = NotImplementedError.new
-      middle = ActiveRecord::StatementInvalid.new('boop', original)
-      top = ActionView::Template::Error.new('boop', middle)
+      top = twice_wrapped_exception(ActionView::Template::Error, ActiveRecord::StatementInvalid, NotImplementedError)
 
       expect(lb.connection_error?(top)).to eq(true)
     end
@@ -276,7 +307,7 @@ describe Gitlab::Database::LoadBalancing::LoadBalancer do
     end
 
     it 'returns true for a wrapped error' do
-      wrapped = ActionView::Template::Error.new('boop', conflict_error.new)
+      wrapped = wrapped_exception(ActionView::Template::Error, conflict_error)
 
       expect(lb.serialization_failure?(wrapped)).to eq(true)
     end