Fixed: FileSystem.waitForFile: do not crash if directory does not exist yet (#5420)

fs.watch() throws for a missing directory, and the timeout callback
then accesses the uninitialized watcher, which kills the process with
a ReferenceError. Poll with fileExists() instead, like seeFile() does.

Author: danielrentz

lib/helper/FileSystem.js

@@ -100,17 +100,18 @@ class FileSystem extends Helper {
    */
   async waitForFile(name, sec = 1) {
     if (sec === 0) assert.fail('Use `seeFile` instead of waiting 0 seconds!')
-    const waitTimeout = sec * 1000
     this.file = path.join(this.dir, name)
     try {
       this.debugSection('File', this.file)
     } catch (e) {
       // Fallback debug for ESM transition
       console.log(`[File] ${this.file}`)
     }
-    return isFileExists(this.file, waitTimeout).catch(() => {
-      throw new Error(`file (${name}) still not present in directory ${this.dir} after ${waitTimeout / 1000} sec`)
-    })
+    const endTime = Date.now() + sec * 1000
+    while (!fileExists(this.file)) {
+      if (endTime < Date.now()) throw new Error(`file (${name}) still not present in directory ${this.dir} after ${sec} sec`)
+      await new Promise(resolve => setTimeout(resolve, 200))
+    }
   }
 
   /**
@@ -213,36 +214,3 @@ function getFileContents(file, encoding = 'utf8') {
   if (encoding === '') assert.fail('Encoding is an empty string, please set a valid encoding')
   return fs.readFileSync(file, encoding)
 }
-
-/**
- * @param {string} file
- * @param {number} timeout
- * @private
- * @returns {Promise<any>}
- */
-function isFileExists(file, timeout) {
-  return new Promise((resolve, reject) => {
-    const timer = setTimeout(() => {
-      watcher.close()
-      reject(new Error('File did not exists and was not created during the timeout.'))
-    }, timeout)
-
-    const dir = path.dirname(file)
-    const basename = path.basename(file)
-    const watcher = fs.watch(dir, (eventType, filename) => {
-      if (eventType === 'rename' && filename === basename) {
-        clearTimeout(timer)
-        watcher.close()
-        resolve()
-      }
-    })
-
-    fs.access(file, fs.constants.R_OK, err => {
-      if (!err) {
-        clearTimeout(timer)
-        watcher.close()
-        resolve()
-      }
-    })
-  })
-}

test/unit/helper/FileSystem_test.js

@@ -77,4 +77,33 @@ describe('FileSystem', () => {
     fs.seeFile(outputFilePath)
     fs.seeInThisFile(text)
   })
+
+  describe('#waitForFile', () => {
+    const waitDir = path.join('data', 'output', 'wait_for_file')
+
+    beforeEach(() => {
+      nodeFs.rmSync(path.join(global.codecept_dir, waitDir), { recursive: true, force: true })
+      fs.amInPath(waitDir)
+    })
+
+    it('should wait for a file in a directory that does not exist yet', async () => {
+      setTimeout(() => {
+        nodeFs.mkdirSync(fs.dir, { recursive: true })
+        nodeFs.writeFileSync(path.join(fs.dir, 'file.txt'), 'content')
+      }, 300)
+      await fs.waitForFile('file.txt', 3)
+    })
+
+    it('should fail after the timeout if the directory does not exist', async () => {
+      const start = Date.now()
+      let error
+      try {
+        await fs.waitForFile('file.txt', 1)
+      } catch (err) {
+        error = err
+      }
+      expect(error?.message).to.include('file (file.txt) still not present')
+      expect(Date.now() - start).to.be.at.least(1000)
+    })
+  })
 })