diff --git a/lib/listeners.js b/lib/listeners.js
deleted file mode 100644
index ec22ab3..0000000
--- a/lib/listeners.js
+++ /dev/null
@@ -1,19 +0,0 @@
-import { onSubprocessData } from './onData.js'
-import { onSpawnError, onSubprocessError } from './onError.js'
-
-/**
- * Handle events from child_process
- * @param {SevenZipStream} stream
- */
-export function listenStdEvents (stream) {
-  stream._childProcess.stdout.on('data', function (chunk) {
-    onSubprocessData(stream, chunk)
-  })
-  stream._childProcess.stderr.on('data', function (chunk) {
-    onSubprocessError(stream, chunk)
-  })
-  stream._childProcess.on('error', function (err) {
-    onSpawnError(stream, err)
-  })
-  return stream
-}
diff --git a/lib/onData.js b/lib/onData.js
deleted file mode 100644
index 56ae2a5..0000000
--- a/lib/onData.js
+++ /dev/null
@@ -1,78 +0,0 @@
-import { STAGE_HEADERS, STAGE_FILES, STAGE_FOOTER } from './references.js'
-import { matchLine } from './parser.js'
-
-/**
- * Data handling.
- * @param {SevenZipStream} stream Instance of the worker
- * @param {Buffer} chunk Buffer from `stdout`
- * @emits SevenZipStream#progress
- */
-export function onSubprocessData (stream, chunk) {
-  let lines = chunk.toString().split('\n')
-
-  // When the `-bsp1` switch is specified 7zip output a line
-  // containing the progress percentage and the file count as far.
-  lines.forEach(function (line) {
-    const matchProgress = matchLine(line, 'progress')
-    if (matchProgress) {
-      stream.emit('progress', matchProgress.groups)
-    }
-  })
-
-  // Chunks of data aren't line-by-line, a chunk can begin and end in the
-  // middle of line. The following code insure that if a line is not
-  // complete it goes to the next stream
-  const isPreviousLastLine = (stream._lastLine)
-  if (isPreviousLastLine) {
-    lines[0] = stream._lastLine.concat(lines[0])
-  }
-  const newLastLine = lines[lines.length - 1]
-  const isNewLastLineComplete = (newLastLine.indexOf('\n') === newLastLine.length - 1)
-  if (!isNewLastLineComplete) {
-    stream._lastLine = newLastLine
-    lines.pop()
-  } else {
-    delete stream._lastLine
-  }
-
-  lines.forEach(function (line) {
-    // Add info to steam. Only run the regexp when the stream is on
-    // `STAGE_HEADERS` for perf improvment
-    if (stream._stage === STAGE_HEADERS) {
-      const matchHeadersInfo = matchLine(line, 'infoHeaders')
-      if (matchHeadersInfo) {
-        stream.info[matchHeadersInfo.property] = matchHeadersInfo.value
-        return
-      }
-    }
-
-    // An empty line is created at the end of the listing of files. This empty
-    // line means that 7zip has reached the end of the listing, and will next
-    // outputs infos for the STAGE_FOOTER.
-    if (stream._stage === STAGE_FILES) {
-      const isLineEmpty = (line === '')
-      if (isLineEmpty) {
-        stream._stage = STAGE_FOOTER
-      }
-      return
-    }
-
-    // Add info to steam. Only run the regexp when the stream is on
-    // `STAGE_FOOTER` for perf improvment
-    if (stream._stage === STAGE_FOOTER) {
-      const matchFooterInfo = matchLine(line, 'infoFooter')
-      if (matchFooterInfo) {
-        stream.info[matchFooterInfo.property] = matchFooterInfo.value
-      }
-      return
-    }
-
-    // Parser function call. Only push to stream when the parser return non-null
-    // data. Pushing null will cause the stream to end.
-    const matchFile = matchLine(line, stream._parser)
-    if (matchFile) {
-      stream._stage = STAGE_FILES
-      stream.push(matchFile)
-    }
-  })
-}
diff --git a/lib/onError.js b/lib/onError.js
deleted file mode 100644
index 064edbb..0000000
--- a/lib/onError.js
+++ /dev/null
@@ -1,35 +0,0 @@
-// @TODO parser error using parser.js
-/**
- * Regexp to be match againt stderr 
- */
-const inLineErrorRegExp = /ERROR: (?<message>.*)\n/
-const offLineErrorRegExp = /ERROR:\n(?<message>.*)\n/
-
-/**
- * Error handling. An error from `stderr`
- * @param {SevenZipStream} stream Instance of the worker
- * @param {Error} chunk Error emitted by `child_process.spawn()`
- * @emits SevenZipStream#error
- */
-export function onSubprocessError (stream, chunk) {
-  const stderr = chunk.toString()
-  const inLineError = stderr.match(inLineErrorRegExp)
-  const offLineError = stderr.match(offLineErrorRegExp)
-  let message = 'unknown error'
-  message = (inLineError) ? inLineError.groups.message : message
-  message = (offLineError) ? offLineError.groups.message : message
-  const err = new Error(message)
-  err.stderr = stderr // @TODO doc: usage of raw stderr to get more info
-  stream.emit('error', err)
-}
-
-/**
- * Error handling. An error can be from the `spawn()` call
- * @param {SevenZipStream} stream Instance of the worker
- * @param {Error} err Error emitted by `child_process.spawn()`
- * @see https://nodejs.org/api/child_process.html#child_process_event_error
- * @emits SevenZipStream#error
- */
-export function onSpawnError (stream, err) {
-  stream.emit('error', err)
-}
diff --git a/lib/stream.js b/lib/stream.js
index 6f6cedf..dcce082 100644
--- a/lib/stream.js
+++ b/lib/stream.js
@@ -1,8 +1,10 @@
 import { spawn } from 'cross-spawn'
 import { Readable } from 'stream'
+import { STAGE_HEADERS, STAGE_FILES, STAGE_FOOTERS } from './references.js'
 import { transformPathToString, transformRawToArgs, transformWildCardsToArgs } from './special.js'
 import { transformSwitchesToArgs } from './switches.js'
-import { STAGE_HEADERS } from './references.js'
+import { matchProgress } from './parser.js'
+import { add } from './infos.js'
 
 /**
  * Wrapper around the `child_process.spawn()` call
@@ -14,7 +16,9 @@ export class SevenZipStream extends Readable {
     super(options)
 
     const stream = this
-    stream._parser = options._parser
+    stream._matchHeaders = options._matchHeaders
+    stream._matchFiles = options._matchFiles
+    stream._matchFooters = options._matchFooters
     stream._stage = STAGE_HEADERS
     stream.info = {}
 
@@ -27,7 +31,17 @@ export class SevenZipStream extends Readable {
       .concat(wildcards)
       .concat(switches)
       .concat(raw)
-    stream._childProcess = spawn(pathSpawn, args)
+    stream._pathSpawn = pathSpawn
+    stream._args = args
+    stream._childProcess = options.$childProcess
+
+    // When $differ option is specified the stream is constructed but the
+    // child_process is not spawned, nor the llisteners are attached. It allows 
+    // easier testing with mock stdout and some advanced usages.
+    if (!options.$defer) {
+      stream.spawn()
+      stream.listen()
+    }
 
     return stream
   }
@@ -39,4 +53,136 @@ export class SevenZipStream extends Readable {
   // `stdout` can be lost.
   // [https://github.com/nodejs/help/issues/963#issuecomment-372007824]
   _read (size) {}
+
+  // Register listeners
+  listen () {
+    const stream = this
+    // Attach listeners @TODO end/close events
+    const stdout = stream._childProcess.stdout
+    const stderr = stream._childProcess.stderr
+    stdout.on('data', function (chunk) {
+      stream.onSubprocessData(chunk)
+    })
+    stdout.on('end', function () {
+      stream.emit('end')
+    })
+    stderr.on('data', function (chunk) {
+      stream.onSubprocessError(chunk)
+    })
+    stream._childProcess.on('error', function (err) {
+      stream.onSpawnError(err)
+    })
+    return this
+  }
+
+  // Run child process
+  spawn () {
+    this._childProcess = spawn(this._pathSpawn, this._args)
+    return this
+  }
+
+  addInfos (infos) {
+    let stream = this
+    infos.forEach(function (info) {
+      Object.assign(stream.info, info)
+    })
+    return this
+  }
+
+  onSubprocessData (chunk) {
+    const stream = this
+
+    // Lines are separated by the END OF LINE symbol. When 7zip writes a 
+    // progress value to stdout a new line is not created: Instead 7zip uses
+    // a combination on backpaces and spaces char.
+    let lines = chunk.toString().split(/\n|\x08/)
+
+    // Chunks of data aren't line-by-line, a chunk can begin and end in the
+    // middle of line. The following code insure that if a line is not
+    // complete it goes to the next stream
+    const isPreviousLastLine = (stream._lastLine)
+    if (isPreviousLastLine) {
+      lines[0] = stream._lastLine.concat(lines[0])
+    }
+    const newLastLine = lines[lines.length - 1]
+    const isNewLastLineComplete = (newLastLine.indexOf('\n') === newLastLine.length - 1)
+    if (!isNewLastLineComplete) {
+      stream._lastLine = newLastLine
+      lines.pop()
+    } else {
+      delete stream._lastLine
+    }
+
+    // When the `-bsp1` switch is specified 7zip output a line
+    // containing the progress percentage and the file count as far.
+    lines.forEach(function (line) {
+      const progress = matchProgress(line)
+      if (progress) {
+        stream.emit('progress', progress)
+      
+        const isSymbolFile = (progress.symbol && progress.file)
+        if (isSymbolFile) {
+          stream._stage = STAGE_FILES
+          stream.push(progress)
+          return
+        }
+      }
+
+      // Add info to steam. Only run the regexp when the stream is on
+      // `STAGE_HEADERS` for perf improvment
+      if (stream._stage === STAGE_HEADERS) {
+        const matchHeaders = stream._matchHeaders(line)
+        if (matchHeaders) {
+          stream.addInfos(matchHeaders)
+          return
+        }
+      }
+
+      // An empty line is created at the end of the listing of files. This empty
+      // line means that 7zip has reached the end of the listing, and will next
+      // outputs infos for the STAGE_FOOTERS.
+      if (stream._stage === STAGE_FILES) {
+        const isLineEmpty = (line === '')
+        if (isLineEmpty) {
+          stream._stage = STAGE_FOOTERS
+        }
+        return
+      }
+
+      // Add info to steam. Only run the regexp when the stream is on
+      // `STAGE_FOOTERS` for perf improvment
+      if (stream._stage === STAGE_FOOTERS) {
+        const matchFooters = stream._matchFooters(line)
+        if (matchFooters) {
+          stream.addInfos(matchFooters)
+        }
+        return
+      }
+
+    })
+
+    return this
+  }
+
+  onSubprocessError (chunk) {
+    const stderr = chunk.toString()
+    const inLineErrorRegExp = /ERROR: (?<message>.*)\n/
+    const offLineErrorRegExp = /ERROR:\n(?<message>.*)\n/
+    const inLineError = stderr.match(inLineErrorRegExp)
+    const offLineError = stderr.match(offLineErrorRegExp)
+    let message = 'unknown error'
+    message = (inLineError) ? inLineError.groups.message : message
+    message = (offLineError) ? offLineError.groups.message : message
+    const err = new Error(message)
+    err.stderr = stderr // @TODO doc: usage of raw stderr to get more info
+    this.emit('error', err)
+   
+    return this
+  }
+
+  onSpawnError (err) {
+    this.emit('error', err)
+
+    return this
+  }
 }