feat: refactor and test tools steps utilities (#42693)

tools/challenge-helper-scripts/helpers/get-last-step-file-content.js

@@ -0,0 +1,35 @@
+const fs = require('fs');
+const path = require('path');
+const { getChallengeSeeds } = require('../utils');
+const { getProjectPath } = require('./get-project-path');
+
+// Looks up the last file found with format `part-###.md` in a directory and
+// returns associated information to it. At the same time validates that the
+// number of files match the names used to name these.
+function getLastStepFileContent() {
+  const filesArr = [];
+  const projectPath = getProjectPath();
+
+  fs.readdirSync(projectPath).forEach(fileName => {
+    if (
+      path.extname(fileName).toLowerCase() === '.md' &&
+      !fileName.endsWith('final.md')
+    ) {
+      filesArr.push(fileName);
+    }
+  });
+
+  const fileName = filesArr[filesArr.length - 1];
+  let lastStepFileNum = fileName.split('.')[0].split('-')[1];
+  lastStepFileNum = parseInt(lastStepFileNum, 10);
+  if (filesArr.length !== lastStepFileNum) {
+    throw `Error: The last file step is ${lastStepFileNum} and there are ${filesArr.length} files.`;
+  }
+
+  return {
+    challengeSeeds: getChallengeSeeds(projectPath + fileName),
+    nextStepNum: lastStepFileNum + 1
+  };
+}
+
+exports.getLastStepFileContent = getLastStepFileContent;