1 files changed, 137 insertions, 0 deletions
diff --git a/spec/lib/gitlab/diff/line_mapper_spec.rb b/spec/lib/gitlab/diff/line_mapper_spec.rb
new file mode 100644
index 00000000000..4e50e03bb7e
--- /dev/null
+++ b/spec/lib/gitlab/diff/line_mapper_spec.rb
@@ -0,0 +1,137 @@
+require 'spec_helper'
+
+describe Gitlab::Diff::LineMapper, lib: true do
+  include RepoHelpers
+
+  let(:project) { create(:project) }
+  let(:repository) { project.repository }
+  let(:commit) { project.commit(sample_commit.id) }
+  let(:diffs) { commit.diffs }
+  let(:diff) { diffs.first }
+  let(:diff_file) { Gitlab::Diff::File.new(diff, diff_refs: commit.diff_refs, repository: repository) }
+  subject { described_class.new(diff_file) }
+
+  describe '#old_to_new' do
+    context "with a diff file" do
+      let(:mapping) do
+        {
+          1 => 1,
+          2 => 2,
+          3 => 3,
+          4 => 4,
+          5 => 5,
+          6 => 6,
+          7 => 7,
+          8 => 8,
+          9 => nil,
+          # nil => 9,
+          10 => 10,
+          11 => 11,
+          12 => 12,
+          13 => nil,
+          14 => nil,
+          # nil => 15,
+          # nil => 16,
+          # nil => 17,
+          # nil => 18,
+          # nil => 19,
+          # nil => 20,
+          15 => 21,
+          16 => 22,
+          17 => 23,
+          18 => 24,
+          19 => 25,
+          20 => 26,
+          21 => 27,
+          # nil => 28,
+          22 => 29,
+          23 => 30,
+          24 => 31,
+          25 => 32,
+          26 => 33,
+          27 => 34,
+          28 => 35,
+          29 => 36,
+          30 => 37
+        }
+      end
+
+      it 'returns the new line number for the old line number' do
+        mapping.each do |old_line, new_line|
+          expect(subject.old_to_new(old_line)).to eq(new_line)
+        end
+      end
+    end
+
+    context "without a diff file" do
+      let(:diff_file) { nil }
+
+      it "returns the same line number" do
+        expect(subject.old_to_new(100)).to eq(100)
+      end
+    end
+  end
+
+  describe '#new_to_old' do
+    context "with a diff file" do
+      let(:mapping) do
+        {
+          1 => 1,
+          2 => 2,
+          3 => 3,
+          4 => 4,
+          5 => 5,
+          6 => 6,
+          7 => 7,
+          8 => 8,
+          # nil => 9,
+          9 => nil,
+          10 => 10,
+          11 => 11,
+          12 => 12,
+          # nil => 13,
+          # nil => 14,
+          13 => nil,
+          14 => nil,
+          15 => nil,
+          16 => nil,
+          17 => nil,
+          18 => nil,
+          19 => nil,
+          20 => nil,
+          21 => 15,
+          22 => 16,
+          23 => 17,
+          24 => 18,
+          25 => 19,
+          26 => 20,
+          27 => 21,
+          28 => nil,
+          29 => 22,
+          30 => 23,
+          31 => 24,
+          32 => 25,
+          33 => 26,
+          34 => 27,
+          35 => 28,
+          36 => 29,
+          37 => 30
+        }
+      end
+
+      it 'returns the old line number for the new line number' do
+        mapping.each do |new_line, old_line|
+          expect(subject.new_to_old(new_line)).to eq(old_line)
+        end
+      end
+    end
+
+    context "without a diff file" do
+      let(:diff_file) { nil }
+
+      it "returns the same line number" do
+        expect(subject.new_to_old(100)).to eq(100)
+      end
+    end
+  end
+end