1 files changed, 44 insertions, 0 deletions
diff --git a/tooling/lib/tooling/crystalball/coverage_lines_execution_detector.rb b/tooling/lib/tooling/crystalball/coverage_lines_execution_detector.rb
new file mode 100644
index 00000000000..47ddf568fe4
--- /dev/null
+++ b/tooling/lib/tooling/crystalball/coverage_lines_execution_detector.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+require 'crystalball/map_generator/helpers/path_filter'
+
+module Tooling
+  module Crystalball
+    # Class for detecting code execution path based on coverage information diff
+    class CoverageLinesExecutionDetector
+      include ::Crystalball::MapGenerator::Helpers::PathFilter
+
+      attr_reader :exclude_prefixes
+
+      def initialize(*args, exclude_prefixes: [])
+        super(*args)
+        @exclude_prefixes = exclude_prefixes
+      end
+
+      # Detects files affected during example execution based on line coverage.
+      # Transforms absolute paths to relative.
+      # Exclude paths outside of repository and in excluded prefixes
+      #
+      # @param[Hash] hash of files affected before example execution
+      # @param[Hash] hash of files affected after example execution
+      # @return [Array<String>]
+      def detect(before, after)
+        file_names = after.keys
+        covered_files = file_names.reject { |file_name| same_coverage?(before, after, file_name) }
+        filter(covered_files)
+      end
+
+      private
+
+      def same_coverage?(before, after, file_name)
+        before[file_name] && before[file_name][:lines] == after[file_name][:lines]
+      end
+
+      def filter(paths)
+        super.reject do |file_name|
+          exclude_prefixes.any? { |prefix| file_name.start_with?(prefix) }
+        end
+      end
+    end
+  end
+end