fix: The 'rerun' event is no longer emitted on the initial bundling of a file (#103)

Author: chrisbreiding

.eslintignore

@@ -13,3 +13,4 @@ examples/use-babelrc/cypress/integration/spec.js
 dist
 tsconfig.json
 .vscode/
+.history

index.ts

@@ -11,9 +11,13 @@ const debug = require('debug')('cypress:webpack')
 const debugStats = require('debug')('cypress:webpack:stats')
 
 type FilePath = string
+interface BundleObject {
+  promise: Promise<FilePath>
+  initial: boolean
+}
 
 // bundle promises from input spec filename to output bundled file paths
-let bundles: {[key: string]: Promise<FilePath>} = {}
+let bundles: {[key: string]: BundleObject} = {}
 
 // we don't automatically load the rules, so that the babel dependencies are
 // not required if a user passes in their own configuration
@@ -164,7 +168,7 @@ const preprocessor: WebpackPreprocessor = (options: PreprocessorOptions = {}): F
     if (bundles[filePath]) {
       debug(`already have bundle for ${filePath}`)
 
-      return bundles[filePath]
+      return bundles[filePath].promise
     }
 
     const defaultWebpackOptions = getDefaultWebpackOptions()
@@ -229,7 +233,10 @@ const preprocessor: WebpackPreprocessor = (options: PreprocessorOptions = {}): F
 
     // cache the bundle promise, so it can be returned if this function
     // is invoked again with the same filePath
-    bundles[filePath] = latestBundle.promise
+    bundles[filePath] = {
+      promise: latestBundle.promise,
+      initial: true,
+    }
 
     const rejectWithErr = (err: Error) => {
       err = quietErrorMessage(err)
@@ -294,19 +301,24 @@ const preprocessor: WebpackPreprocessor = (options: PreprocessorOptions = {}): F
       // we overwrite the latest bundle, so that a new call to this function
       // returns a promise that resolves when the bundling is finished
       latestBundle = createDeferred<string>()
-      bundles[filePath] = latestBundle.promise
+      bundles[filePath].promise = latestBundle.promise
 
-      bundles[filePath].finally(() => {
-        debug('- compile finished for', filePath)
+      bundles[filePath].promise.finally(() => {
+        debug('- compile finished for %s, initial? %s', filePath, bundles[filePath].initial)
         // when the bundling is finished, emit 'rerun' to let Cypress
-        // know to rerun the spec
-        file.emit('rerun')
+        // know to rerun the spec, but NOT when it is the initial
+        // bundling of the file
+        if (!bundles[filePath].initial) {
+          file.emit('rerun')
+        }
+
+        bundles[filePath].initial = false
       })
       // we suppress unhandled rejections so they don't bubble up to the
       // unhandledRejection handler and crash the process. Cypress will
       // eventually take care of the rejection when the file is requested.
       // note that this does not work if attached to latestBundle.promise
-      // for some reason. it only works when attached after .tap  ¯\_(ツ)_/¯
+      // for some reason. it only works when attached after .finally  ¯\_(ツ)_/¯
       .suppressUnhandledRejections()
     }
 
@@ -341,7 +353,7 @@ const preprocessor: WebpackPreprocessor = (options: PreprocessorOptions = {}): F
 
     // return the promise, which will resolve with the outputPath or reject
     // with any error encountered
-    return bundles[filePath]
+    return bundles[filePath].promise
   }
 }
 

package.json

@@ -14,13 +14,13 @@
     "secure": "nsp check",
     "semantic-release": "semantic-release",
     "size": "npm pack --dry",
-    "pretest": "yarn lint && yarn build",
     "test": "yarn test-unit && yarn test-e2e",
     "test-debug": "node --inspect --debug-brk ./node_modules/.bin/_mocha",
     "test-e2e": "mocha test/e2e/*.spec.*",
     "test-unit": "mocha test/unit/*.spec.*",
     "test-watch": "yarn test-unit & chokidar '**/*.(js|ts)' 'test/unit/*.(js|ts)' -c 'yarn test-unit'",
-    "types": "tsc --noEmit"
+    "types": "tsc --noEmit",
+    "watch": "yarn build --watch"
   },
   "husky": {
     "hooks": {
@@ -37,6 +37,7 @@
     "@babel/plugin-proposal-nullish-coalescing-operator": "7.8.3",
     "@babel/preset-env": "^7.0.0",
     "@cypress/eslint-plugin-dev": "5.0.0",
+    "@fellow/eslint-plugin-coffee": "0.4.13",
     "@types/webpack": "4.41.12",
     "@typescript-eslint/eslint-plugin": "2.31.0",
     "@typescript-eslint/parser": "2.31.0",

test/e2e/compilation.spec.js

@@ -19,25 +19,20 @@ const normalizeErrMessage = (message) => {
 const fixturesDir = path.join(__dirname, '..', 'fixtures')
 const outputDir = path.join(__dirname, '..', '_test-output')
 
+const createFile = ({ name = 'example_spec.js', shouldWatch = false } = {}) => {
+  return Object.assign(new EventEmitter(), {
+    filePath: path.join(outputDir, name),
+    outputPath: path.join(outputDir, name.replace('.', '_output.')),
+    shouldWatch,
+  })
+}
+
 describe('webpack preprocessor - e2e', () => {
-  let run
   let file
 
   beforeEach(async () => {
     preprocessor.__reset()
 
-    run = ({ options, keepFile, shouldWatch = false, fileName = 'example_spec.js' } = {}) => {
-      if (!keepFile) {
-        file = Object.assign(new EventEmitter(), {
-          filePath: path.join(outputDir, fileName),
-          outputPath: path.join(outputDir, fileName.replace('.', '_output.')),
-          shouldWatch,
-        })
-      }
-
-      return preprocessor(options)(file)
-    }
-
     await fs.remove(outputDir)
     await fs.copy(fixturesDir, outputDir)
   })
@@ -54,14 +49,17 @@ describe('webpack preprocessor - e2e', () => {
     const options = preprocessor.defaultOptions
 
     options.webpackOptions.mode = 'production' // snapshot will be minified
+    file = createFile()
 
-    return run({ options }).then((outputPath) => {
+    return preprocessor(options)(file).then((outputPath) => {
       snapshot(fs.readFileSync(outputPath).toString())
     })
   })
 
   it('has less verbose "Module not found" error', () => {
-    return run({ fileName: 'imports_nonexistent_file_spec.js' })
+    file = createFile({ name: 'imports_nonexistent_file_spec.js' })
+
+    return preprocessor()(file)
     .then(() => {
       throw new Error('Should not resolve')
     })
@@ -71,7 +69,9 @@ describe('webpack preprocessor - e2e', () => {
   })
 
   it('has less verbose syntax error', () => {
-    return run({ fileName: 'syntax_error_spec.js' })
+    file = createFile({ name: 'syntax_error_spec.js' })
+
+    return preprocessor()(file)
     .then(() => {
       throw new Error('Should not resolve')
     })
@@ -87,12 +87,14 @@ describe('webpack preprocessor - e2e', () => {
       throw new Error('Should not have trigger unhandled rejection')
     })
 
-    await run({ shouldWatch: true })
+    file = createFile({ shouldWatch: true })
+
+    await preprocessor()(file)
     await fs.outputFile(file.filePath, '{')
 
     await new Promise((resolve) => {
       setTimeout(() => {
-        run({ keepFile: true, shouldWatch: true })
+        preprocessor()(file)
         .catch((err) => {
           expect(err.stack).to.include('Unexpected token')
           resolve()
@@ -102,14 +104,29 @@ describe('webpack preprocessor - e2e', () => {
   })
 
   it('triggers rerun on syntax error', async () => {
-    await run({ shouldWatch: true })
+    file = createFile({ shouldWatch: true })
+
+    await preprocessor()(file)
 
     const _emit = sinon.spy(file, 'emit')
 
     await fs.outputFile(file.filePath, '{')
 
     await retry(() => expect(_emit).calledWith('rerun'))
   })
+
+  it('does not call rerun on initial build, but on subsequent builds', async () => {
+    file = createFile({ shouldWatch: true })
+    const _emit = sinon.spy(file, 'emit')
+
+    await preprocessor()(file)
+
+    expect(_emit).not.to.be.calledWith('rerun')
+
+    await fs.outputFile(file.filePath, 'console.log()')
+
+    await retry(() => expect(_emit).calledWith('rerun'))
+  })
 })
 
 function retry (fn, timeout = 1000) {

test/unit/index.spec.js

@@ -2,6 +2,7 @@
 
 const chai = require('chai')
 const mockery = require('mockery')
+const Promise = require('bluebird')
 const sinon = require('sinon')
 
 const expect = chai.expect
@@ -247,12 +248,21 @@ describe('webpack preprocessor', function () {
         })
       })
 
-      it('emits "rerun" when shouldWatch is true and there is an update', function () {
+      it('emits "rerun" when shouldWatch is true after there is an update', function () {
         this.file.shouldWatch = true
         this.compilerApi.watch.yields(null, this.statsApi)
         this.compilerApi.plugin.withArgs('compile').yields()
 
-        return this.run().then(() => {
+        return this.run()
+        .then(() => {
+          expect(this.file.emit).not.to.be.calledWith('rerun')
+
+          this.compilerApi.plugin.withArgs('compile').yield()
+          this.compilerApi.watch.yield(null, this.statsApi)
+
+          return Promise.delay(10) // give assertion time till next tick
+        })
+        .then(() => {
           expect(this.file.emit).to.be.calledWith('rerun')
         })
       })