1 files changed, 58 insertions, 0 deletions
diff --git a/tooling/lib/tooling/test_map_packer.rb b/tooling/lib/tooling/test_map_packer.rb
new file mode 100644
index 00000000000..520d69610eb
--- /dev/null
+++ b/tooling/lib/tooling/test_map_packer.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+module Tooling
+  class TestMapPacker
+    SEPARATOR = '/'.freeze
+    MARKER = 1
+
+    def pack(map)
+      map.transform_values(&method(:create_tree_from_tests))
+    end
+
+    def unpack(compact_map)
+      compact_map.transform_values(&method(:retrieve_tests_from_tree))
+    end
+
+    private
+
+    def create_tree_from_tests(tests)
+      tests.inject({}) do |tree, test|
+        segments = test.split(SEPARATOR)
+        branch = create_branch_from_segments(segments)
+        deep_merge(tree, branch)
+      end
+    end
+
+    def create_branch_from_segments(segments)
+      segments.reverse.inject(MARKER) { |node, parent| { parent => node } }
+    end
+
+    def deep_merge(hash, other)
+      hash.merge(other) do |_, this_val, other_val|
+        if this_val.is_a?(Hash) && other_val.is_a?(Hash)
+          deep_merge(this_val, other_val)
+        else
+          other_val
+        end
+      end
+    end
+
+    def retrieve_tests_from_tree(tree)
+      traverse(tree).inject([]) do |tests, test|
+        tests << test
+      end
+    end
+
+    def traverse(tree, segments = [], &block)
+      return to_enum(__method__, tree, segments) unless block_given?
+
+      if tree == MARKER
+        return yield segments.join(SEPARATOR)
+      end
+
+      tree.each do |key, value|
+        traverse(value, segments + [key], &block)
+      end
+    end
+  end
+end