Compare images mathematically instead of checksums, closes #31

.travis.yml

@@ -13,7 +13,7 @@ before_script:
   - greenkeeper-lockfile-update
 
 script:
-  - ./node_modules/.bin/nyc --check-coverage --lines 90 npm test
+  - ./node_modules/.bin/nyc --check-coverage --lines 90 npm test --serial
 
 after_script:
   - ./node_modules/.bin/nyc report --reporter=text-lcov | ./node_modules/.bin/coveralls

package.json

@@ -6,7 +6,8 @@
   "scripts": {
     "start": "node src/server.js",
     "start-dev": "nodemon src/server.js --watch src/",
-    "test": "standard --fix && ava --serial"
+    "test": "standard && ava",
+    "fix-style": "standard --fix"
   },
   "dependencies": {
     "dotenv": "4.0.0",
@@ -19,8 +20,10 @@
   "devDependencies": {
     "ava": "0.24.0",
     "coveralls": "3.0.0",
+    "jpeg-js": "0.3.3",
     "nodemon": "1.14.6",
     "nyc": "11.4.1",
+    "pixelmatch": "4.0.2",
     "rimraf": "2.6.2",
     "standard": "10.0.3",
     "supertest": "3.0.0"

tests/macros/validateReceivedImages.js

@@ -1,9 +1,15 @@
+// Native Node.js modules
 const fs = require('fs')
 const path = require('path')
+const promisify = require('util').promisify
+
+// Third party dependencies
 const supertest = require('supertest')
-const crypto = require('crypto')
 const rimraf = require('rimraf')
+const pixelmatch = require('pixelmatch')
+const jpegParser = require('jpeg-js')
 
+// Local modules
 const app = require('./../../src/app')
 const getSourceSamples = require('./../helpers/getSourceSamples')
 
@@ -15,9 +21,14 @@ module.exports = function validateReceivedImages (t, source) {
 
   return Promise.all(samples.files.map(file =>
             Promise.all([
-              getFileHash(samples.dir, file),
-              getReceivedHash(receivablesDir, source, file)
-            ]).then(hashes => t.is(hashes[0], hashes[1], file + ' is different'))
+              path.join(samples.dir, file),
+              getReceivedImage(receivablesDir, source, file)
+            ]).then(images => {
+              const sample = parseImage(images[0])
+              const received = parseImage(images[1])
+              const diff = pixelmatch(sample, received, null, sample.width, sample.height)
+              t.is(diff, 0, file + ' is different')
+            })
         )
     )
 }
@@ -27,23 +38,18 @@ function clearDir (dir) {
   fs.mkdirSync(dir)
 }
 
-function getReceivedHash (receivablesDir, source, file) {
+function getReceivedImage (receivablesDir, source, file) {
   return new Promise(resolve => {
     supertest(app)
         .get(`/${source}/` + path.parse(file).name)
         .pipe(fs.createWriteStream(path.join(receivablesDir, file)))
-        .on('close', () => resolve(getFileHash(receivablesDir, file)))
+        .on('finish', () => resolve(path.join(receivablesDir, file)))
   })
 }
 
-function getFileHash (dir, file) {
-  return new Promise(resolve => {
-    const hash = crypto.createHash('sha1')
-    hash.on('readable', () => {
-      const result = hash.read()
-      if (result) { resolve(result.toString('hex')) }
-    })
-
-    fs.ReadStream(path.join(dir, file)).pipe(hash)
-  })
+async function parseImage (file) {
+  return jpegParser.decode(
+    await promisify(fs.readFile)(file),
+    true
+  )
 }