1 files changed, 30 insertions, 0 deletions
diff --git a/spec/lib/gitlab/git/diff_tree_spec.rb b/spec/lib/gitlab/git/diff_tree_spec.rb
new file mode 100644
index 00000000000..614a8f03dd8
--- /dev/null
+++ b/spec/lib/gitlab/git/diff_tree_spec.rb
@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe Gitlab::Git::DiffTree, feature_category: :source_code_management do
+  let_it_be(:project) { create(:project, :repository) }
+  let_it_be(:repository) { project.repository }
+
+  describe '.from_commit' do
+    subject(:diff_tree) { described_class.from_commit(commit) }
+
+    context 'when commit is an initial commit' do
+      let(:commit) { repository.commit('1a0b36b3cdad1d2ee32457c102a8c0b7056fa863') }
+
+      it 'returns the expected diff tree object' do
+        expect(diff_tree.left_tree_id).to eq(Gitlab::Git::EMPTY_TREE_ID)
+        expect(diff_tree.right_tree_id).to eq(commit.tree_id)
+      end
+    end
+
+    context 'when commit is a regular commit' do
+      let(:commit) { repository.commit('60ecb67744cb56576c30214ff52294f8ce2def98') }
+
+      it 'returns the expected diff tree object' do
+        expect(diff_tree.left_tree_id).to eq(commit.parent.tree_id)
+        expect(diff_tree.right_tree_id).to eq(commit.tree_id)
+      end
+    end
+  end
+end