feat(scripts): stop caching challenges and improve build scripts

Avoid caching challenges so that changes can be hotloaded into Gatsby.  Add scripts to watch
challenges and atomically copy them to the dist directory, without minification.

ISSUES CLOSED: #68

Author: ojeytonwilliams

getChallenges.js

@@ -4,7 +4,7 @@ const fs = require('fs');
 const path = require('path');
 const omit = require('lodash/omit');
 
-const hiddenFile = /(^(\.|\/\.))|(.md$)/g;
+const hiddenFile = /(^(\.|\/\.))|(.md$)|(~$)/g;
 
 function getFilesFor(dir) {
   let targetDir = path.join(__dirname, dir);
@@ -47,7 +47,12 @@ module.exports = function getChallenges(challengesDir) {
     challengesDir = 'challenges';
   }
   return getFilesFor(challengesDir).map(function(data) {
-    const challengeSpec = require('./' + challengesDir + '/' + data.file);
+    // During development, challenge files are often read multiple times.
+    // As a result, rather than clear the require cache we read them directly.
+    const rawChallenge = fs.readFileSync(
+      path.join(__dirname, challengesDir, data.file)
+    );
+    const challengeSpec = JSON.parse(rawChallenge);
     let superInfo = superblockInfo(data.superBlock);
     challengeSpec.fileName = data.file;
     challengeSpec.superBlock = superInfo.name;

gulpfile.js

@@ -3,27 +3,56 @@ const util = require('gulp-util');
 const jsonMinify = require('gulp-json-minify');
 const babel = require('gulp-babel');
 const rename = require('gulp-rename');
+const path = require('path');
+const fs = require('fs');
 
-gulp.task('json:minify', function() {
-  return gulp.src('./challenges/**/*.json')
-      .pipe(jsonMinify())
-      .pipe(gulp.dest('dist/challenges/'))
-      .on('error', util.log);
+gulp.task('json:minify', () =>
+  gulp
+    .src('./challenges/**/*.json')
+    .pipe(jsonMinify())
+    .pipe(gulp.dest('dist/challenges/'))
+    .on('error', util.log)
+);
+
+gulp.task('json:copy', () =>
+  gulp
+    .src('./challenges/**/*.json')
+    .pipe(gulp.dest('dist/challenges/'))
+    .on('error', util.log)
+);
+
+gulp.task('json:watch', ['json:copy'], () => {
+  gulp.watch('./challenges/**/*.json', event => {
+    // Copying via streams can result in dist files being updated incrementally
+    // this means that, if it is watching, Gatsby might try to read an
+    // unfinished file.
+    util.log('Updating', event.path);
+    const src = event.path;
+    const tail = src.split(path.sep).slice(-2);
+    const dest = path.join(__dirname, 'dist', 'challenges', ...tail);
+    fs.copyFileSync(src, dest);
+  });
 });
 
 gulp.task('babel-getChallenges', () =>
-  gulp.src('./getChallenges.js')
-    .pipe(babel({
-      presets: ['env']
-    }))
+  gulp
+    .src('./getChallenges.js')
+    .pipe(
+      babel({
+        presets: ['env']
+      })
+    )
     .pipe(gulp.dest('dist'))
 );
 
 gulp.task('babel', ['babel-getChallenges'], () =>
-  gulp.src('./package-entry.js')
-  .pipe(rename('./index.js'))
-  .pipe(babel({
-    presets: ['env']
-  }))
-  .pipe(gulp.dest('dist/'))
+  gulp
+    .src('./package-entry.js')
+    .pipe(rename('./index.js'))
+    .pipe(
+      babel({
+        presets: ['env']
+      })
+    )
+    .pipe(gulp.dest('dist/'))
 );