Add specs for Gitlab::Diff::Highlight. #3945

spec/lib/gitlab/diff/highlight_spec.rb

+require 'spec_helper'
+
+describe Gitlab::Diff::Highlight, lib: true do
+  include RepoHelpers
+
+  let(:project) { create(:project) }
+  let(:commit) { project.commit(sample_commit.id) }
+  let(:diff) { commit.diffs.first }
+  let(:diff_file) { Gitlab::Diff::File.new(diff) }
+
+  describe '.process_diff_lines' do
+    let(:diff_lines) { Gitlab::Diff::Highlight.process_diff_lines(diff_file) }
+
+    it 'should return Gitlab::Diff::Line elements' do
+      expect(diff_lines.first).to be_an_instance_of(Gitlab::Diff::Line)
+    end
+
+    it 'should highlight the code' do
+      code = %Q{<span id="LC3" class="line">   <span class="k">def</span> <span class="nf">popen</span><span class="p">(</span><span class="n">cmd</span><span class="p">,</span> <span class="n">path</span><span class="o">=</span><span class="kp">nil</span><span class="p">)</span></span>\n}
+
+      expect(diff_lines[2].text).to eq(code)
+    end
+
+    it 'should keep the inline diff markup' do
+      expect(diff_lines[5].text).to match(Regexp.new(Regexp.escape('<span class="idiff">RuntimeError, </span>')))
+    end
+  end
+end