feat: test page structure (#59113)

Co-authored-by: Naomi <accounts+github@nhcarrigan.com>
Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>

tools/challenge-parser/parser/__fixtures__/with-subsection.md

@@ -0,0 +1,19 @@
+# --description--
+
+Paragraph 1
+
+```html
+code example
+```
+
+## --not-allowed--
+
+should not be allowed
+
+# --instructions--
+
+Paragraph 0
+
+```html
+code example 0
+```

tools/challenge-parser/parser/plugins/add-text.js

@@ -1,5 +1,7 @@
 const { isEmpty } = require('lodash');
-const { getSection } = require('./utils/get-section');
+const find = require('unist-util-find');
+const { root } = require('mdast-builder');
+const { getSection, isMarker } = require('./utils/get-section');
 const mdastToHTML = require('./utils/mdast-to-html');
 
 function addText(sectionIds) {
@@ -9,6 +11,13 @@ function addText(sectionIds) {
   function transformer(tree, file) {
     for (const sectionId of sectionIds) {
       const textNodes = getSection(tree, `--${sectionId}--`);
+      const subSection = find(root(textNodes), isMarker);
+      if (subSection) {
+        throw Error(
+          `The --${sectionId}-- section should not have any subsections. Found subsection ${subSection.children[0].value}`
+        );
+      }
+
       const sectionText = mdastToHTML(textNodes);
 
       if (!isEmpty(sectionText)) {

tools/challenge-parser/parser/plugins/add-text.test.js

@@ -2,7 +2,7 @@ const parseFixture = require('../__fixtures__/parse-fixture');
 const addText = require('./add-text');
 
 describe('add-text', () => {
-  let realisticAST, mockAST;
+  let realisticAST, mockAST, withSubSectionAST;
   const descriptionId = 'description';
   const instructionsId = 'instructions';
   const missingId = 'missing';
@@ -11,6 +11,7 @@ describe('add-text', () => {
   beforeAll(async () => {
     realisticAST = await parseFixture('realistic.md');
     mockAST = await parseFixture('simple.md');
+    withSubSectionAST = await parseFixture('with-subsection.md');
   });
 
   beforeEach(() => {
@@ -43,6 +44,16 @@ describe('add-text', () => {
     }).toThrow(expectedError);
   });
 
+  it('throws when there is a sub-section in one of the sections', () => {
+    const plugin = addText([instructionsId, descriptionId]);
+
+    expect(() => {
+      plugin(withSubSectionAST, file);
+    }).toThrow(
+      'The --description-- section should not have any subsections. Found subsection --not-allowed--'
+    );
+  });
+
   it('should add a string relating to the section id to `file.data`', () => {
     const plugin = addText([descriptionId]);
     plugin(mockAST, file);

tools/challenge-parser/parser/plugins/utils/get-section.js

@@ -4,27 +4,25 @@ const findAllAfter = require('unist-util-find-all-after');
 const between = require('unist-util-find-all-between');
 const { findAll } = require('./find-all');
 
+const isMarker = node => {
+  if (node.children && node.children[0]) {
+    const child = node.children[0];
+    return (
+      child.type === 'text' &&
+      child.value.startsWith('--') &&
+      child.value.endsWith('--') &&
+      node.type === 'heading'
+    );
+  }
+  return false;
+};
+
 function _getSection(tree) {
   return start => {
     if (!start) return [];
 
     const isEnd = node => {
-      return (
-        node.type === 'heading' && node.depth <= start.depth && isMarker(node)
-      );
-    };
-
-    const isMarker = node => {
-      if (node.children && node.children[0]) {
-        const child = node.children[0];
-        return (
-          child.type === 'text' &&
-          child.value.startsWith('--') &&
-          child.value.endsWith('--')
-        );
-      } else {
-        return false;
-      }
+      return node.depth <= start.depth && isMarker(node);
     };
 
     const end = findAfter(tree, start, isEnd);
@@ -56,4 +54,4 @@ function getAllSections(tree, marker) {
   return starts.map(_getSection(tree));
 }
 
-module.exports = { getSection, getAllSections };
+module.exports = { getSection, getAllSections, isMarker };