Add tests for DiffPositionUpdateService

spec/services/notes/diff_position_update_service_spec.rb

+require 'spec_helper'
+
+describe Notes::DiffPositionUpdateService, services: true do
+  let(:project) { create(:project) }
+  let(:create_commit) { project.commit("913c66a37b4a45b9769037c55c2d238bd0942d2e") }
+  let(:modify_commit) { project.commit("874797c3a73b60d2187ed6e2fcabd289ff75171e") }
+  let(:edit_commit) { project.commit("570e7b2abdd848b95f2f578043fc23bd6f6fd24d") }
+
+  let(:path) { "files/ruby/popen.rb" }
+
+  let(:old_diff_refs) do
+    Gitlab::Diff::DiffRefs.new(
+      base_sha: create_commit.parent_id,
+      head_sha: modify_commit.sha
+    )
+  end
+
+  let(:new_diff_refs) do
+    Gitlab::Diff::DiffRefs.new(
+      base_sha: create_commit.parent_id,
+      head_sha: edit_commit.sha
+    )
+  end
+
+  subject do
+    described_class.new(
+      project,
+      nil,
+      old_diff_refs: old_diff_refs,
+      new_diff_refs: new_diff_refs,
+      paths: [path]
+    )
+  end
+
+  describe "#execute" do
+    let(:note) { create(:diff_note_on_merge_request, project: project, position: old_position) }
+
+    let(:old_position) do
+      Gitlab::Diff::Position.new(
+        old_path: path,
+        new_path: path,
+        old_line: nil,
+        new_line: line,
+        diff_refs: old_diff_refs
+      )
+    end
+
+    context "when the diff line is the same" do
+      let(:line) { 16 }
+
+      it "updates the position" do
+        subject.execute(note)
+
+        expect(note.original_position).to eq(old_position)
+        expect(note.position).not_to eq(old_position)
+        expect(note.position.new_line).to eq(22)
+      end
+    end
+
+    context "when the diff line has changed" do
+      let(:line) { 9 }
+
+      it "doesn't update the position" do
+        subject.execute(note)
+
+        expect(note.original_position).to eq(old_position)
+        expect(note.position).to eq(old_position)
+      end
+    end
+  end
+end