1 files changed, 77 insertions, 0 deletions
diff --git a/spec/tooling/lib/tooling/test_map_packer_spec.rb b/spec/tooling/lib/tooling/test_map_packer_spec.rb
new file mode 100644
index 00000000000..233134d2524
--- /dev/null
+++ b/spec/tooling/lib/tooling/test_map_packer_spec.rb
@@ -0,0 +1,77 @@
+# frozen_string_literal: true
+
+require_relative '../../../../tooling/lib/tooling/test_map_packer'
+
+RSpec.describe Tooling::TestMapPacker do
+  subject { described_class.new }
+
+  let(:map) do
+    {
+      'file1.rb' => [
+        './a/b/c/test_1.rb',
+        './a/b/test_2.rb',
+        './a/b/test_3.rb',
+        './a/test_4.rb',
+        './test_5.rb'
+      ],
+      'file2.rb' => [
+        './a/b/c/test_1.rb',
+        './a/test_4.rb',
+        './test_5.rb'
+      ]
+    }
+  end
+
+  let(:compact_map) do
+    {
+      'file1.rb' => {
+        '.' => {
+          'a' => {
+            'b' => {
+              'c' => {
+                'test_1.rb' => 1
+              },
+              'test_2.rb' => 1,
+              'test_3.rb' => 1
+            },
+            'test_4.rb' => 1
+          },
+          'test_5.rb' => 1
+        }
+      },
+      'file2.rb' => {
+        '.' => {
+          'a' => {
+            'b' => {
+              'c' => {
+                'test_1.rb' => 1
+              }
+            },
+            'test_4.rb' => 1
+          },
+          'test_5.rb' => 1
+        }
+      }
+    }
+  end
+
+  describe '#pack' do
+    it 'compacts list of test files into a prefix tree' do
+      expect(subject.pack(map)).to eq(compact_map)
+    end
+
+    it 'does nothing to empty hash' do
+      expect(subject.pack({})).to eq({})
+    end
+  end
+
+  describe '#unpack' do
+    it 'unpack prefix tree into list of test files' do
+      expect(subject.unpack(compact_map)).to eq(map)
+    end
+
+    it 'does nothing to empty hash' do
+      expect(subject.unpack({})).to eq({})
+    end
+  end
+end