private static string ReadExpected(this TestSolution solution) => solution.ReadFile("expected_representation.txt").NormalizeWhiteSpace();
private static string ReadActual(this TestSolution solution) => solution.ReadFile("representation.txt").NormalizeWhiteSpace();
private static Dictionary <string, string> ReadMapping(this TestSolution solution, string fileName) => JsonSerializer.Deserialize <Dictionary <string, string> >(solution.ReadFile(fileName));