diff --git a/test/parallel/test-repl-line-queue.js b/test/parallel/test-repl-line-queue.js
index dd793a0b54eddd..7d5b28e1e442f7 100644
--- a/test/parallel/test-repl-line-queue.js
+++ b/test/parallel/test-repl-line-queue.js
@@ -5,27 +5,128 @@ require('../common');
 const ArrayStream = require('../common/arraystream');
 
 const assert = require('assert');
-const repl = require('repl');
 
 function* expectedLines(lines) {
   for (const line of lines) {
     yield line;
   }
-  throw new Error('Requested more lines than expected');
 }
 
+const expectedDebug = expectedLines([
+  [
+    'line %j',
+    'const x = await new Promise((r) => setTimeout(() => r(1), 500));',
+  ],
+  [
+    'eval %j',
+    'const x = await new Promise((r) => setTimeout(() => r(1), 500));\n',
+  ],
+  ['queued line %j', 'x;'],
+  ['finish', null, undefined],
+  ['line %j', 'x;'],
+  ['eval %j', 'x;\n'],
+  ['finish', null, 1],
+  ['line %j', 'const y = 3;'],
+  ['eval %j', 'const y = 3;\n'],
+  ['finish', null, undefined],
+  ['line %j', 'x + y;'],
+  ['eval %j', 'x + y;\n'],
+  ['finish', null, 4],
+  ['line %j', 'const z = 4;'],
+  ['eval %j', 'const z = 4;\n'],
+  ['finish', null, undefined],
+  ['queued line %j', 'z + 1'],
+  ['line %j', 'z + 1'],
+  ['eval %j', 'z + 1\n'],
+  ['finish', null, 5],
+]);
+
+let calledDebug = false;
+require('internal/util/debuglog').debuglog = () => {
+  return (...args) => {
+    calledDebug = true;
+    assert.deepStrictEqual(args, expectedDebug.next().value);
+  };
+};
+
+// Import `repl` after replacing original `debuglog`
+const repl = require('repl');
+
 const putIn = new ArrayStream();
 repl.start({
   input: putIn,
   output: putIn,
-  useGlobal: false
+  useGlobal: false,
 });
 
-const expectedOutput = expectedLines(['undefined\n', '> ', '1\n', '> ']);
-putIn.write = function(data) {
+const expectedOutput = expectedLines([
+  'undefined\n',
+  '> ',
+  '1\n',
+  '> ',
+  'undefined\n',
+  '> ',
+  '4\n',
+  '> ',
+  'undefined\n',
+  '> ',
+  '5\n',
+  '> ',
+]);
+
+let calledOutput = false;
+function writeCallback(data) {
+  calledOutput = true;
   assert.strictEqual(data, expectedOutput.next().value);
-};
+}
 
-putIn.run([
-  'const x = await new Promise((r) => setTimeout(() => r(1), 500));\nx;',
-]);
+putIn.write = writeCallback;
+
+function clearCalled() {
+  calledDebug = false;
+  calledOutput = false;
+}
+
+// Lines sent after an async command that hasn't finished
+// in the same write are enqueued
+function test1() {
+  putIn.run([
+    'const x = await new Promise((r) => setTimeout(() => r(1), 500));\nx;',
+  ]);
+  assert(calledDebug);
+
+  setTimeout(() => {
+    assert(calledOutput);
+    clearCalled();
+
+    test2();
+  }, 1000);
+}
+
+// Lines sent after a sync command in the same write are not enqueued
+function test2() {
+  putIn.run(['const y = 3;\nx + y;']);
+
+  assert(calledDebug);
+  assert(calledOutput);
+  clearCalled();
+
+  test3();
+}
+
+// Lines sent during an output write event of a previous command
+// are enqueued
+function test3() {
+  putIn.write = (data) => {
+    writeCallback(data);
+    putIn.write = writeCallback;
+    putIn.run(['z + 1']);
+  };
+
+  putIn.run(['const z = 4;']);
+
+  assert(calledDebug);
+  assert(calledOutput);
+}
+
+test1();