test: move common.ArrayStream to separate module

In a continuing effort to de-monolithize `require('../common')`,
move `common.ArrayStream` out to a separate module that is
imported only when it is needed.

PR-URL: https://github.com/nodejs/node/pull/22447
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

3 files changed, 38 insertions, 21 deletions

diff --git a/test/common/README.md b/test/common/README.md
index 27634c97e1..e44dcd299c 100644
--- a/test/common/README.md
+++ b/test/common/README.md
@@ -38,9 +38,6 @@ tasks.
 
 Takes `whitelist` and concats that with predefined `knownGlobals`.
 
-### arrayStream
-A stream to push an array into a REPL
-
 ### busyLoop(time)
 * `time` [<number>]
 
@@ -413,6 +410,20 @@ Platform normalizes the `pwd` command.
 
 Synchronous version of `spawnPwd`.
 
+## ArrayStream Module
+
+The `ArrayStream` module provides a simple `Stream` that pushes elements from
+a given array.
+
+<!-- eslint-disable no-undef, node-core/required-modules -->
+```js
+const ArrayStream = require('../common/arraystream');
+const stream = new ArrayStream();
+stream.run(['a', 'b', 'c']);
+```
+
+It can be used within tests as a simple mock stream.
+
 ## Countdown Module
 
 The `Countdown` module provides a simple countdown mechanism for tests that
diff --git a/test/common/arraystream.js b/test/common/arraystream.js
new file mode 100644
index 0000000000..dadd6ff048
--- /dev/null
+++ b/test/common/arraystream.js
@@ -0,0 +1,24 @@
+/* eslint-disable node-core/required-modules */
+'use strict';
+
+const { Stream } = require('stream');
+const { inherits } = require('util');
+function noop() {}
+
+// A stream to push an array into a REPL
+function ArrayStream() {
+  this.run = function(data) {
+    data.forEach((line) => {
+      this.emit('data', `${line}\n`);
+    });
+  };
+}
+
+inherits(ArrayStream, Stream);
+ArrayStream.prototype.readable = true;
+ArrayStream.prototype.writable = true;
+ArrayStream.prototype.pause = noop;
+ArrayStream.prototype.resume = noop;
+ArrayStream.prototype.write = noop;
+
+module.exports = ArrayStream;
diff --git a/test/common/index.js b/test/common/index.js
index 8254f54101..369f23f790 100644
--- a/test/common/index.js
+++ b/test/common/index.js
@@ -27,7 +27,6 @@ const fs = require('fs');
 const assert = require('assert');
 const os = require('os');
 const { exec, execSync, spawn, spawnSync } = require('child_process');
-const stream = require('stream');
 const util = require('util');
 const { fixturesDir } = require('./fixtures');
 const tmpdir = require('./tmpdir');
@@ -511,23 +510,6 @@ exports.skip = function(msg) {
   process.exit(0);
 };
 
-// A stream to push an array into a REPL
-function ArrayStream() {
-  this.run = function(data) {
-    data.forEach((line) => {
-      this.emit('data', `${line}\n`);
-    });
-  };
-}
-
-util.inherits(ArrayStream, stream.Stream);
-exports.ArrayStream = ArrayStream;
-ArrayStream.prototype.readable = true;
-ArrayStream.prototype.writable = true;
-ArrayStream.prototype.pause = noop;
-ArrayStream.prototype.resume = noop;
-ArrayStream.prototype.write = noop;
-
 // Returns true if the exit code "exitCode" and/or signal name "signal"
 // represent the exit code and/or signal name of a node process that aborted,
 // false otherwise.