1 files changed, 44 insertions, 0 deletions
diff --git a/spec/lib/api/entities/merge_request_diff_spec.rb b/spec/lib/api/entities/merge_request_diff_spec.rb
new file mode 100644
index 00000000000..a6927914316
--- /dev/null
+++ b/spec/lib/api/entities/merge_request_diff_spec.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe ::API::Entities::MergeRequestDiff, feature_category: :code_review_workflow do
+  let_it_be(:user)          { create(:user) }
+  let_it_be(:merge_request) { create(:merge_request) }
+  let_it_be(:project)       { merge_request.target_project }
+  let_it_be(:entity)        { described_class.new(merge_request.merge_request_diffs.first) }
+
+  before do
+    merge_request.merge_request_diffs.create!(head_commit_sha: '6f6d7e7ed97bb5f0054f2b1df789b39ca89b6ff9')
+    merge_request.merge_request_diffs.create!(head_commit_sha: '5937ac0a7beb003549fc5fd26fc247adbce4a52e')
+  end
+
+  subject(:json) { entity.as_json }
+
+  it "includes expected fields" do
+    expected_fields = %i[
+      id head_commit_sha base_commit_sha start_commit_sha created_at
+      merge_request_id state real_size patch_id_sha
+    ]
+
+    is_expected.to include(*expected_fields)
+  end
+
+  it "returns expected data" do
+    merge_request_diff = merge_request.merge_request_diffs.first
+
+    expect(entity.as_json).to eq(
+      {
+        id: merge_request_diff.id,
+        head_commit_sha: merge_request_diff.head_commit_sha,
+        base_commit_sha: merge_request_diff.base_commit_sha,
+        start_commit_sha: merge_request_diff.start_commit_sha,
+        created_at: merge_request_diff.created_at,
+        merge_request_id: merge_request.id,
+        state: merge_request_diff.state,
+        real_size: merge_request_diff.real_size,
+        patch_id_sha: merge_request_diff.patch_id_sha
+      }
+    )
+  end
+end