Add a test for a position without lines

spec/requests/api/graphql/mutations/notes/create/diff_note_spec.rb

@@ -9,8 +9,9 @@ RSpec.describe 'Adding a DiffNote' do
   let(:noteable) { create(:merge_request, source_project: project, target_project: project) }
   let(:project) { create(:project, :repository) }
   let(:diff_refs) { noteable.diff_refs }
-  let(:mutation) do
-    variables = {
+
+  let(:base_variables) do
+    {
       noteable_id: GitlabSchema.id_from_object(noteable).to_s,
       body: 'Body text',
       position: {
@@ -18,16 +19,16 @@ RSpec.describe 'Adding a DiffNote' do
           old_path: 'files/ruby/popen.rb',
           new_path: 'files/ruby/popen2.rb'
         },
-        new_line: 14,
         base_sha: diff_refs.base_sha,
         head_sha: diff_refs.head_sha,
         start_sha: diff_refs.start_sha
       }
     }
-
-    graphql_mutation(:create_diff_note, variables)
   end
 
+  let(:variables) { base_variables.deep_merge({ position: { new_line: 14 } }) }
+  let(:mutation) { graphql_mutation(:create_diff_note, variables) }
+
   def mutation_response
     graphql_mutation_response(:create_diff_note)
   end
@@ -42,28 +43,17 @@ RSpec.describe 'Adding a DiffNote' do
     it_behaves_like 'a Note mutation that creates a Note'
 
     context 'add comment to old line' do
-      let(:mutation) do
-        variables = {
-          noteable_id: GitlabSchema.id_from_object(noteable).to_s,
-          body: 'Body text',
-          position: {
-            paths: {
-              old_path: 'files/ruby/popen.rb',
-              new_path: 'files/ruby/popen.rb'
-            },
-            old_line: 14,
-            base_sha: diff_refs.base_sha,
-            head_sha: diff_refs.head_sha,
-            start_sha: diff_refs.start_sha
-          }
-        }
-
-        graphql_mutation(:create_diff_note, variables)
-      end
+      let(:variables) { base_variables.deep_merge({ position: { old_line: 14 } }) }
 
       it_behaves_like 'a Note mutation that creates a Note'
     end
 
+    context 'add a comment with a position without lines' do
+      let(:variables) { base_variables }
+
+      it_behaves_like 'a Note mutation that does not create a Note'
+    end
+
     it_behaves_like 'a Note mutation when there are active record validation errors', model: DiffNote
 
     it_behaves_like 'a Note mutation when there are rate limit validation errors'