feat: allow next challenge's seed to be a solution (#39145)

* feat: allow next challenge's seed to be a solution

curriculum/test/test-challenges.js

@@ -23,7 +23,7 @@ const {
 
 const { assert, AssertionError } = require('chai');
 const Mocha = require('mocha');
-const { flatten } = require('lodash');
+const { flatten, isEmpty } = require('lodash');
 
 const jsdom = require('jsdom');
 
@@ -51,6 +51,7 @@ const {
 } = require('../../client/src/templates/Challenges/utils/build');
 
 const { createPoly } = require('../../utils/polyvinyl');
+const { sortChallenges } = require('./utils/sort-challenges');
 
 const testEvaluator = require('../../client/config/test-evaluator').filename;
 
@@ -226,7 +227,9 @@ async function getChallenges(lang) {
         return [...challengeArray, ...flatten(challengesForBlock)];
       }, [])
   );
-  return challenges;
+  // This matches the order Gatsby uses (via a GraphQL query). Ideally both
+  // should be sourced and sorted using a single query, but we're not there yet.
+  return sortChallenges(challenges);
 }
 
 function validateBlock(challenge) {
@@ -245,7 +248,7 @@ function populateTestsForLang({ lang, challenges, meta }) {
 
   describe(`Check challenges (${lang})`, function() {
     this.timeout(5000);
-    challenges.forEach(challenge => {
+    challenges.forEach((challenge, id) => {
       const dashedBlockName = dasherize(challenge.block);
       describe(challenge.block || 'No block', function() {
         describe(challenge.title || 'No title', function() {
@@ -367,6 +370,15 @@ function populateTestsForLang({ lang, challenges, meta }) {
           });
 
           let { solutions = [] } = challenge;
+          // if there are no solutions in the challenge, it's assumed the next
+          // challenge's seed will be a solution to the current challenge.
+          // This is expected to happen in the project based curriculum.
+          if (isEmpty(solutions)) {
+            const nextChallenge = challenges[id + 1];
+            if (nextChallenge) {
+              solutions = [nextChallenge.files[0].contents];
+            }
+          }
           const noSolution = new RegExp('// solution required');
           solutions = solutions.filter(
             solution => !!solution && !noSolution.test(solution)

curriculum/test/utils/sort-challenges.js

@@ -0,0 +1,5 @@
+const { sortBy } = require('lodash');
+
+exports.sortChallenges = arr => {
+  return sortBy(arr, ['superOrder', 'order', 'challengeOrder']);
+};

curriculum/test/utils/sort-challenges.test.js

@@ -0,0 +1,252 @@
+/* global expect */
+const { sortChallenges } = require('./sort-challenges');
+
+const challenges = [
+  {
+    name: 'HTML - project 1 - step 1',
+    superOrder: 1,
+    order: 1,
+    challengeOrder: 1
+  },
+  {
+    name: 'HTML - project 1 - step 2',
+    superOrder: 1,
+    order: 1,
+    challengeOrder: 2
+  },
+  {
+    name: 'HTML - project 1 - step 3',
+    superOrder: 1,
+    order: 1,
+    challengeOrder: 3
+  },
+  {
+    name: 'HTML - project 1 - step 4',
+    superOrder: 1,
+    order: 1,
+    challengeOrder: 4
+  },
+  {
+    name: 'HTML - project 2 - step 1',
+    superOrder: 1,
+    order: 2,
+    challengeOrder: 1
+  },
+  {
+    name: 'HTML - project 2 - step 2',
+    superOrder: 1,
+    order: 2,
+    challengeOrder: 2
+  },
+  {
+    name: 'HTML - project 2 - step 3',
+    superOrder: 1,
+    order: 2,
+    challengeOrder: 3
+  },
+  {
+    name: 'HTML - project 2 - step 4',
+    superOrder: 1,
+    order: 2,
+    challengeOrder: 4
+  },
+  {
+    name: 'HTML - project 3 - step 1',
+    superOrder: 1,
+    order: 3,
+    challengeOrder: 1
+  },
+  {
+    name: 'HTML - project 3 - step 2',
+    superOrder: 1,
+    order: 3,
+    challengeOrder: 2
+  },
+  {
+    name: 'HTML - project 3 - step 3',
+    superOrder: 1,
+    order: 3,
+    challengeOrder: 3
+  },
+  {
+    name: 'HTML - project 3 - step 4',
+    superOrder: 1,
+    order: 3,
+    challengeOrder: 4
+  },
+  {
+    name: 'CSS - project 1 - step 1',
+    superOrder: 2,
+    order: 1,
+    challengeOrder: 1
+  },
+  {
+    name: 'CSS - project 1 - step 2',
+    superOrder: 2,
+    order: 1,
+    challengeOrder: 2
+  },
+  {
+    name: 'CSS - project 1 - step 3',
+    superOrder: 2,
+    order: 1,
+    challengeOrder: 3
+  },
+  {
+    name: 'CSS - project 1 - step 4',
+    superOrder: 2,
+    order: 1,
+    challengeOrder: 4
+  },
+  {
+    name: 'CSS - project 2 - step 1',
+    superOrder: 2,
+    order: 2,
+    challengeOrder: 1
+  },
+  {
+    name: 'CSS - project 2 - step 2',
+    superOrder: 2,
+    order: 2,
+    challengeOrder: 2
+  },
+  {
+    name: 'CSS - project 2 - step 3',
+    superOrder: 2,
+    order: 2,
+    challengeOrder: 3
+  },
+  {
+    name: 'CSS - project 2 - step 4',
+    superOrder: 2,
+    order: 2,
+    challengeOrder: 4
+  },
+  {
+    name: 'CSS - project 3 - step 1',
+    superOrder: 2,
+    order: 3,
+    challengeOrder: 1
+  },
+  {
+    name: 'CSS - project 3 - step 2',
+    superOrder: 2,
+    order: 3,
+    challengeOrder: 2
+  },
+  {
+    name: 'CSS - project 3 - step 3',
+    superOrder: 2,
+    order: 3,
+    challengeOrder: 3
+  },
+  {
+    name: 'CSS - project 3 - step 4',
+    superOrder: 2,
+    order: 3,
+    challengeOrder: 4
+  },
+  {
+    name: 'JS - project 1 - step 1',
+    superOrder: 3,
+    order: 1,
+    challengeOrder: 1
+  },
+  {
+    name: 'JS - project 1 - step 2',
+    superOrder: 3,
+    order: 1,
+    challengeOrder: 2
+  },
+  {
+    name: 'JS - project 1 - step 3',
+    superOrder: 3,
+    order: 1,
+    challengeOrder: 3
+  },
+  {
+    name: 'JS - project 1 - step 4',
+    superOrder: 3,
+    order: 1,
+    challengeOrder: 4
+  },
+  {
+    name: 'JS - project 2 - step 1',
+    superOrder: 3,
+    order: 2,
+    challengeOrder: 1
+  },
+  {
+    name: 'JS - project 2 - step 2',
+    superOrder: 3,
+    order: 2,
+    challengeOrder: 2
+  },
+  {
+    name: 'JS - project 2 - step 3',
+    superOrder: 3,
+    order: 2,
+    challengeOrder: 3
+  },
+  {
+    name: 'JS - project 2 - step 4',
+    superOrder: 3,
+    order: 2,
+    challengeOrder: 4
+  },
+  {
+    name: 'JS - project 3 - step 1',
+    superOrder: 3,
+    order: 3,
+    challengeOrder: 1
+  },
+  {
+    name: 'JS - project 3 - step 2',
+    superOrder: 3,
+    order: 3,
+    challengeOrder: 2
+  },
+  {
+    name: 'JS - project 3 - step 3',
+    superOrder: 3,
+    order: 3,
+    challengeOrder: 3
+  },
+  {
+    name: 'JS - project 3 - step 4',
+    superOrder: 3,
+    order: 3,
+    challengeOrder: 4
+  }
+];
+
+describe('sortChallenges', () => {
+  it('sorts challenges by superblock, block and challenge order', () => {
+    const copyOfChallenges = [...challenges];
+    shuffle(copyOfChallenges);
+    const actualChallenges = sortChallenges(copyOfChallenges);
+
+    expect(actualChallenges).toEqual(challenges);
+  });
+
+  it('does not change the original array', () => {
+    const copyOfChallenges = [...challenges];
+    copyOfChallenges[0] = {
+      name: 'JS - project 3 - step 4',
+      superOrder: 3,
+      order: 3,
+      challengeOrder: 4
+    };
+    const actualChallenges = sortChallenges(copyOfChallenges);
+
+    expect(actualChallenges[0]).not.toEqual(copyOfChallenges[0]);
+  });
+});
+
+// Use the Fisher–Yates shuffle algorithm to shuffle array
+const shuffle = arr => {
+  for (let i = arr.length - 1; i > 0; i--) {
+    const j = Math.floor(Math.random() * (i + 1));
+    [arr[i], arr[j]] = [arr[j], arr[i]];
+  }
+};