Add readme and improve tests usage

__tests__/helpers/fileReader.ts

+const fs = require("fs");
+
+export const listDirectories = (testCasesPath: string): Array<string> => {
+  return fs.readdirSync(testCasesPath).filter(function (file) {
+    return fs.statSync(testCasesPath + "/" + file).isDirectory();
+  });
+};
+
+const filesCache: { [key: string]: string } = {};
+export const readFile = (path: string): string => {
+  if (!filesCache[path]) {
+    filesCache[path] = fs.readFileSync(path).toString();
+  }
+
+  return filesCache[path];
+};