From 9b3385fab417252905975315dfcf1c89e0cc5485 Mon Sep 17 00:00:00 2001
From: Ruben Bridgewater <ruben@bridgewater.de>
Date: Sun, 15 Dec 2019 17:43:46 +0100
Subject: [PATCH 1/2] repl: properly handle `repl.repl`

The repl property is set so that it's possible to inspect the
instances own properties during runtime. This was never tested and
it was also only exported in case the instance was started with
`.start()` instead of using the constructor directly. In case that
more than a single instance was created, all instances got access
to the first instance.

From now on the repl property is only exported in case the repl is
starte as standalone program.
---
 lib/repl.js                        | 22 ++++++++++------------
 test/parallel/test-repl-options.js | 25 +++++++++++++++++++++++++
 2 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/lib/repl.js b/lib/repl.js
index d9efb8c5ece523..44a265a2cca34e 100644
--- a/lib/repl.js
+++ b/lib/repl.js
@@ -234,10 +234,14 @@ function REPLServer(prompt,
     throw new ERR_INVALID_REPL_EVAL_CONFIG();
   }
 
-  // Add this listener only once and use a WeakSet that contains the REPLs
-  // domains. Otherwise we'd have to add a single listener to each REPL instance
-  // and that could trigger the `MaxListenersExceededWarning`.
-  if (!options[kStandaloneREPL] && !addedNewListener) {
+  if (options[kStandaloneREPL]) {
+    // It is possible to introspect the running REPL accessing this variable
+    // from inside the REPL. This is useful for anyone working on the REPL.
+    exports.repl = this;
+  } else if (!addedNewListener) {
+    // Add this listener only once and use a WeakSet that contains the REPLs
+    // domains. Otherwise we'd have to add a single listener to each REPL
+    // instance and that could trigger the `MaxListenersExceededWarning`.
     process.prependListener('newListener', (event, listener) => {
       if (event === 'uncaughtException' &&
           process.domain &&
@@ -895,14 +899,8 @@ exports.start = function(prompt,
                          useGlobal,
                          ignoreUndefined,
                          replMode) {
-  const repl = new REPLServer(prompt,
-                              source,
-                              eval_,
-                              useGlobal,
-                              ignoreUndefined,
-                              replMode);
-  if (!exports.repl) exports.repl = repl;
-  return repl;
+  return new REPLServer(
+    prompt, source, eval_, useGlobal, ignoreUndefined, replMode);
 };
 
 REPLServer.prototype.setupHistory = function setupHistory(historyFile, cb) {
diff --git a/test/parallel/test-repl-options.js b/test/parallel/test-repl-options.js
index 43270e7412d3a2..99f9fa8a605142 100644
--- a/test/parallel/test-repl-options.js
+++ b/test/parallel/test-repl-options.js
@@ -24,6 +24,9 @@ const common = require('../common');
 const ArrayStream = require('../common/arraystream');
 const assert = require('assert');
 const repl = require('repl');
+const cp = require('child_process');
+
+assert.strictEqual(repl.repl, undefined);
 
 common.expectWarning({
   DeprecationWarning: {
@@ -120,3 +123,25 @@ assert.strictEqual(r4.ignoreUndefined, false);
 assert.strictEqual(r4.replMode, repl.REPL_MODE_SLOPPY);
 assert.strictEqual(r4.historySize, 30);
 r4.close();
+
+// Check the standalone REPL
+{
+  const child = cp.spawn(process.execPath, ['--interactive']);
+  let output = '';
+
+  child.stdout.setEncoding('utf8');
+  child.stdout.on('data', (data) => {
+    output += data;
+  });
+
+  child.on('exit', common.mustCall(() => {
+    const results = output.replace(/^> /mg, '').split('\n').slice(2);
+    assert.deepStrictEqual(results, ['undefined', '']);
+  }));
+
+  child.stdin.write(
+    'assert.ok(util.inspect(repl.repl, {depth: -1}).includes("REPLServer"));\n'
+  );
+  child.stdin.write('.exit');
+  child.stdin.end();
+}

From b87844c3d02f2a1c01635399ed7a4a75152daa73 Mon Sep 17 00:00:00 2001
From: Ruben Bridgewater <ruben@bridgewater.de>
Date: Thu, 2 Jan 2020 18:15:20 +0100
Subject: [PATCH 2/2] fixup: fix broken test

---
 test/parallel/test-repl-reverse-search.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/parallel/test-repl-reverse-search.js b/test/parallel/test-repl-reverse-search.js
index a7c736300188de..baafdc9d8fbd33 100644
--- a/test/parallel/test-repl-reverse-search.js
+++ b/test/parallel/test-repl-reverse-search.js
@@ -251,8 +251,8 @@ const tests = [
       '\x1B[1G', '\x1B[0J',
       `${prompt}ab = "aaaa"`, '\x1B[14G',
       '\x1B[1G', '\x1B[0J',
-      `${prompt}repl.repl.historyIndex`, '\x1B[25G', '\n// -1',
-      '\x1B[19C\x1B[1A',
+      `${prompt}repl.repl.historyIndex`, '\x1B[25G', '\n// 8',
+      '\x1B[20C\x1B[1A',
       '\x1B[1B', '\x1B[2K', '\x1B[1A',
       '\nfwd-i-search: _', '\x1B[1A', '\x1B[25G',
       '\x1B[3G', '\x1B[0J',