Fix Error 500 resulting when loading network graph

`discussion_id` may not be present when the SELECT call for notes
does not include this attribute. Don't attempt to set the discussion ID
unless the model contains the attribute.

Closes #21119, #21128

1 files changed, 12 insertions, 0 deletions

diff --git a/spec/models/network/graph_spec.rb b/spec/models/network/graph_spec.rb
new file mode 100644
index 00000000000..b76513d2a3c
--- /dev/null
+++ b/spec/models/network/graph_spec.rb
@@ -0,0 +1,12 @@
+require 'spec_helper'
+
+describe Network::Graph, models: true do
+  let(:project) { create(:project) }
+  let!(:note_on_commit) { create(:note_on_commit, project: project) }
+
+  it '#initialize' do
+    graph = described_class.new(project, 'refs/heads/master', project.repository.commit, nil)
+
+    expect(graph.notes).to eq( { note_on_commit.commit_id => 1 } )
+  end
+end