working more on cypress support

.gitignore

@@ -3,3 +3,4 @@ node_modules/
 npm-debug.log
 src/.snap-shot/
 .snap-shot
+snap-shot.json

cypress/integration/spec.js

@@ -2,13 +2,14 @@ const snapshot = require('../..')
 describe('snap-shot', () => {
   const url = __dirname + '/index.html'
 
-  beforeEach(snapshot.init)
+  before(snapshot.init)
 
   it('works without snapshot', () => {
     expect(cy).to.be.an('object')
   })
 
-  it('works', () => {
+  it.only('works', () => {
+    cy.log('calling snap shot')
     snapshot('foo')
   })
 
@@ -17,9 +18,9 @@ describe('snap-shot', () => {
       .title().should('equal', 'snap-shot')
 
     // same with snap-shot multiple lines
-    cy.title().then(title =>
+    cy.title().then(title => {
       snapshot(title)
-    )
+    })
   })
 
   it('works with arrow function', () => {

src/cypress-system.js

@@ -0,0 +1,96 @@
+'use strict'
+
+const la = require('lazy-ass')
+const is = require('check-more-types')
+const callsites = require('callsites')
+
+// storage adapter for Cypress E2E testing tool
+
+/* global cy, expect, fetch */
+const filename = 'snap-shot.json'
+
+let snapshots
+
+function loadSnapshots () {
+  return snapshots
+}
+
+function saveSnapshots (snapshots) {
+  const text = JSON.stringify(snapshots, null, 2) + '\n'
+  cy.writeFile(filename, text)
+}
+
+function init () {
+  // find out the source for all test -> this spec file
+  const sites = callsites()
+  la(sites.length, 'missing callsite')
+  const specFileUrl = sites[0].getFileName()
+  la(is.webUrl(specFileUrl), 'missing spec url', specFileUrl)
+  console.log('loading spec from', specFileUrl)
+
+  // specFileUrl is something like
+  // http://localhost:49829/__cypress/tests?p=cypress/integration/spec.js-438
+  // we will need to get "true" filename which in this case should be
+  // cypress/integration/spec.js
+  const pIndex = specFileUrl.indexOf('?p=')
+  const dotJsIndex = specFileUrl.indexOf('.js-', pIndex)
+  const specFile = specFileUrl.substr(pIndex + 3, dotJsIndex - pIndex)
+  console.log('specFile is "%s"', specFile)
+
+  // ignore arguments for now
+  api.fromCurrentFolder = () => specFile
+
+  // cache the fetched source, otherwise every test fetches it
+  const shouldFetch = api.readFileSync === dummyReadFileSync
+  if (shouldFetch) {
+    return fetch(specFileUrl).then(r => r.text())
+      .then(source => {
+        // ignores filename for now
+        api.readFileSync = () => source
+      })
+      .then(() => {
+        return fetch('/__cypress/tests?p=' + filename)
+          .then(r => r.text())
+          .then(text => {
+            if (text.includes('BUNDLE_ERROR')) {
+              return Promise.reject(new Error('not found'))
+            }
+            cy.log('loaded snapshots', filename)
+            // the JSON is wrapped in webpack wrapper ;)
+            const req = eval(text) // eslint-disable-line no-eval
+            snapshots = req('1')
+          })
+          .catch(err => {
+            console.error(err)
+            snapshots = {}
+          })
+      })
+  } else {
+    return Promise.resolve()
+  }
+}
+
+function raiseIfDifferent ({value, expected}) {
+  cy.then(() => {
+    expect(value).to.equal(expected)
+  })
+}
+
+function dummyReadFileSync () {
+  throw new Error(`In the browser, please call snapshot.init()
+    before calling tests, like this:
+    const snapshot = require('snap-shot')
+    beforeEach(snapshot.init)
+  `)
+}
+
+// TODO replace exposed API with error methods that wait
+// until "init" is called
+const api = {
+  loadSnapshots,
+  saveSnapshots,
+  init,
+  readFileSync: dummyReadFileSync,
+  raiseIfDifferent
+}
+module.exports = api

src/file-system.js

@@ -2,6 +2,8 @@
 
 const fs = require('fs')
 const path = require('path')
+const diff = require('variable-diff')
+const debug = require('debug')('snap-shot')
 
 const cwd = process.cwd()
 const fromCurrentFolder = path.relative.bind(null, cwd)
@@ -33,9 +35,21 @@ function saveSnapshots (snapshots) {
   return snapshots
 }
 
+function raiseIfDifferent ({value, expected, specName}) {
+  const diffed = diff(expected, value)
+  if (diffed.changed) {
+    const text = diffed.text
+    debug('Test "%s" snapshot difference', specName)
+    const msg = `snapshot difference\n${text}`
+    console.log(msg)
+    throw new Error(msg)
+  }
+}
+
 module.exports = {
   readFileSync: fs.readFileSync,
   fromCurrentFolder,
   loadSnapshots,
-  saveSnapshots
+  saveSnapshots,
+  raiseIfDifferent
 }

src/index.js

@@ -5,20 +5,25 @@ const callsites = require('callsites')
 const falafel = require('falafel')
 const la = require('lazy-ass')
 const is = require('check-more-types')
-const diff = require('variable-diff')
 const crypto = require('crypto')
 const {snapshotIndex} = require('./utils')
 
 // does this test work with jsdom?
 const isBrowser = typeof window === 'object' &&
   (typeof global === 'undefined' || window === global)
+const isCypress = typeof cy === 'object'
 const isNode = !isBrowser
-const fs = isNode ? require('./file-system') : require('./browser-system')
+let fs
+if (isNode) {
+  fs = require('./file-system')
+} else if (isCypress) {
+  fs = require('./cypress-system')
+} else {
+  fs = require('./browser-system')
+}
 
 const shouldUpdate = Boolean(process.env.UPDATE)
 
-const snapshots = fs.loadSnapshots()
-
 function isTestFunctionName (name) {
   return ['it', 'test'].includes(name)
 }
@@ -100,6 +105,18 @@ function getSpecFunction ({file, line}) {
   }
 }
 
+const cacheResult = fn => {
+  let result
+  return () => {
+    if (!result) {
+      result = fn()
+    }
+    return result
+  }
+}
+
+const loadSnapshots = cacheResult(fs.loadSnapshots)
+
 function findStoredValue ({file, specName, index = 0}) {
   const relativePath = fs.fromCurrentFolder(file)
   // console.log('relativePath', relativePath)
@@ -109,6 +126,7 @@ function findStoredValue ({file, specName, index = 0}) {
     return
   }
 
+  const snapshots = loadSnapshots()
   if (!snapshots[relativePath]) {
     return
   }
@@ -129,6 +147,7 @@ function storeValue ({file, specName, index, value}) {
   la(is.number(index), 'missing snapshot index', file, specName, index)
 
   const relativePath = fs.fromCurrentFolder(file)
+  const snapshots = fs.loadSnapshots()
   // console.log('relativePath', relativePath)
   if (!snapshots[relativePath]) {
     snapshots[relativePath] = {}
@@ -198,19 +217,16 @@ function snapshot (what, update) {
     debug('spec "%s" snapshot at line %d is #%d',
       specName, snapshotRelativeLine, index)
 
-    const storedValue = findStoredValue({file, specName, index})
-    if (update || storedValue === undefined) {
+    const expected = findStoredValue({file, specName, index})
+    if (update || expected === undefined) {
       storeValue({file, specName, index, value})
     } else {
-      debug('found snapshot for "%s", value', specName, storedValue)
-      const diffed = diff(storedValue, value)
-      if (diffed.changed) {
-        const text = diffed.text
-        debug('Test "%s" snapshot difference', specName)
-        const msg = `snapshot difference\n${text}`
-        console.log(msg)
-        throw new Error(msg)
-      }
+      debug('found snapshot for "%s", value', specName, expected)
+      fs.raiseIfDifferent({
+        value,
+        expected,
+        specName
+      })
     }
 
     return value