Merge pull request #161 from kien-ht/main

Feat: add an option to fail a test if its baseline doesn't exist

README.md

@@ -117,6 +117,7 @@ Currently supported values in the custom config file:
 - ROOT_DIR (value relative to the root of the directory)
 - FAILURE_THRESHOLD: must be between 0 and 1, default to 0
 - RETRY_OPTIONS: see [retry options](https://www.npmjs.com/package/cypress-recurse#options)
+- FAIL_ON_MISSING_BASELINE: a boolean to determine whether to fail a test if its baseline doesn't exist, default to false
 
 > **Note**: In order to make this custom config values effective, remember to return `getCompareSnapshotsPlugin` instance inside function `setupNodeEvents`:
 

src/command.js

@@ -37,18 +37,21 @@ const compareSnapshotCommand = defaultScreenshotOptions => {
           cy.task('deleteScreenshot', { testName })
           cy.task('deleteReport', { testName })
 
-          // Take a screenshot and copy to baseline if it does not exist
           const objToOperateOn = subject ? cy.get(subject) : cy
-          objToOperateOn
-            .screenshot(testName, defaultScreenshotOptions)
-            .task('copyScreenshot', {
+          const screenshotted = objToOperateOn.screenshot(testName, defaultScreenshotOptions)
+
+          if (userConfig.FAIL_ON_MISSING_BASELINE === false) {
+            // copy to baseline if it does not exist
+            screenshotted.task('copyScreenshot', {
               testName,
             })
+          }
 
           // Compare screenshots
           const options = {
             testName,
             testThreshold,
+            failOnMissingBaseline: userConfig.FAIL_ON_MISSING_BASELINE
           }
 
           return cy.task('compareSnapshotsPlugin', options)

src/config.js

@@ -12,7 +12,8 @@ function getUserConfigFile() {
 const DEFAULT_CONFIG = {
   ROOT_DIR: '',
   FAILURE_THRESHOLD: 0,
-  RETRY_OPTIONS: {}
+  RETRY_OPTIONS: {},
+  FAIL_ON_MISSING_BASELINE: false
 }
 
 export const userConfig = { ...DEFAULT_CONFIG, ...getUserConfigFile() }

src/plugin.js

@@ -59,8 +59,16 @@ const deleteScreenshot = args => {
   return true
 }
 
-async function compareSnapshotsPlugin(args) {
-  const baselineImg = await parseImage(paths.image.baseline(args.testName))
+const getStatsComparisonAndPopulateDiffIfAny = async (args) => {
+  let baselineImg
+  try {
+    baselineImg = await parseImage(paths.image.baseline(args.testName))
+  } catch (e) {
+    return args.failOnMissingBaseline
+      ? { percentage: 1, testFailed: true }
+      : { percentage: 0, testFailed: false }
+  }
+
   const comparisonImg = await parseImage(paths.image.comparison(args.testName))
   const diff = new PNG({
     width: Math.max(comparisonImg.width, baselineImg.width),
@@ -96,6 +104,12 @@ async function compareSnapshotsPlugin(args) {
     diff.pack().pipe(fs.createWriteStream(paths.image.diff(args.testName)))
   }
 
+  return { percentage, testFailed }
+}
+
+async function compareSnapshotsPlugin(args) {
+  const { percentage, testFailed } = await getStatsComparisonAndPopulateDiffIfAny(args)
+
   // Saving test status object to build report if task is triggered
   testStatuses.push(new TestStatus({ 
     status: !testFailed,

src/utils.js

@@ -45,13 +45,13 @@ const renameAndCopyFile = (originalFilePath, newFilePath) => {
 const parseImage = async image => {
   return new Promise((resolve, reject) => {
     const fd = fs.createReadStream(image)
-    fd.pipe(new PNG())
+    fd.on('error', (error) => reject(error))
+      .pipe(new PNG())
       // eslint-disable-next-line func-names
       .on('parsed', function() {
         const that = this
         resolve(that)
       })
-      .on('error', (error) => reject(error))
   })
 }