1 files changed, 62 insertions, 0 deletions
diff --git a/spec/lib/gitlab/diff/custom_diff_spec.rb b/spec/lib/gitlab/diff/custom_diff_spec.rb
new file mode 100644
index 00000000000..246508d2e1e
--- /dev/null
+++ b/spec/lib/gitlab/diff/custom_diff_spec.rb
@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Diff::CustomDiff do
+  include RepoHelpers
+
+  let(:project) { create(:project, :repository) }
+  let(:repository) { project.repository }
+  let(:ipynb_blob) { repository.blob_at('f6b7a707', 'files/ipython/markdown-table.ipynb') }
+  let(:blob) { repository.blob_at('HEAD', 'files/ruby/regex.rb') }
+
+  describe '#preprocess_before_diff' do
+    context 'for ipynb files' do
+      it 'transforms the diff' do
+        expect(described_class.preprocess_before_diff(ipynb_blob.path, nil, ipynb_blob)).not_to include('cells')
+      end
+
+      it 'adds the blob to the list of transformed blobs' do
+        described_class.preprocess_before_diff(ipynb_blob.path, nil, ipynb_blob)
+
+        expect(described_class.transformed_for_diff?(ipynb_blob)).to be_truthy
+      end
+    end
+
+    context 'for other files' do
+      it 'returns nil' do
+        expect(described_class.preprocess_before_diff(blob.path, nil, blob)).to be_nil
+      end
+
+      it 'does not add the blob to the list of transformed blobs' do
+        described_class.preprocess_before_diff(blob.path, nil, blob)
+
+        expect(described_class.transformed_for_diff?(blob)).to be_falsey
+      end
+    end
+  end
+
+  describe '#transformed_blob_data' do
+    it 'transforms blob data if file was processed' do
+      described_class.preprocess_before_diff(ipynb_blob.path, nil, ipynb_blob)
+
+      expect(described_class.transformed_blob_data(ipynb_blob)).not_to include('cells')
+    end
+
+    it 'does not transform blob data if file was not processed' do
+      expect(described_class.transformed_blob_data(ipynb_blob)).to be_nil
+    end
+  end
+
+  describe '#transformed_blob_language' do
+    it 'is md when file was preprocessed' do
+      described_class.preprocess_before_diff(ipynb_blob.path, nil, ipynb_blob)
+
+      expect(described_class.transformed_blob_language(ipynb_blob)).to eq('md')
+    end
+
+    it 'is nil for a .ipynb blob that was not preprocessed' do
+      expect(described_class.transformed_blob_language(ipynb_blob)).to be_nil
+    end
+  end
+end