fixup!

Author: avivkeller

doc/api/repl.md

@@ -232,23 +232,6 @@ undefined
 undefined
 ```
 
-One known limitation of using the `await` keyword in the REPL is that
-it will invalidate the lexical scoping of the `const` keywords.
-
-For example:
-
-```console
-> const m = await Promise.resolve(123)
-undefined
-> m
-123
-> m = await Promise.resolve(234)
-234
-// redeclaring the constant does error
-> const m = await Promise.resolve(345)
-Uncaught SyntaxError: Identifier 'm' has already been declared
-```
-
 ### Reverse-i-search
 
 <!-- YAML

test/parallel/test-repl-custom-eval-previews.js

@@ -29,7 +29,20 @@ function getReplRunOutput(inputStr, replOptions) {
 
     input.emit('data', inputStr);
 
-    input.run(['']);
+    if (!replOptions.preview) {
+      input.run(['']);
+      return;
+    }
+
+    const afterEcho = output.accumulator;
+    let attempts = 0;
+    (function waitForPreview() {
+      if (output.accumulator !== afterEcho || ++attempts > 100) {
+        input.run(['']);
+        return;
+      }
+      setImmediate(waitForPreview);
+    })();
   });
 }
 

test/parallel/test-repl-definecommand.js

@@ -0,0 +1,49 @@
+import '../common/index.mjs';
+import { startNewREPLServer } from '../common/repl.js';
+import assert from 'node:assert';
+
+const { replServer, output, run } = startNewREPLServer({
+  prompt: '> ',
+  terminal: true,
+});
+
+replServer.defineCommand('say1', {
+  help: 'help for say1',
+  action: function (thing) {
+    this.output.accumulator = '';
+    this.output.write(`hello ${thing}\n`);
+    this.displayPrompt();
+  },
+});
+
+replServer.defineCommand('say2', function () {
+  this.output.accumulator = '';
+  this.output.write('hello from say2\n');
+  this.displayPrompt();
+});
+
+await run(['.help\n']);
+assert.match(output.accumulator, /\n\.say1 {5}help for say1\n/);
+assert.match(output.accumulator, /\n\.say2\n/);
+
+await run(['.say1 node developer\n']);
+assert.ok(
+  output.accumulator.startsWith('hello node developer\n'),
+  `say1 output starts incorrectly: "${output.accumulator}"`,
+);
+assert.ok(
+  output.accumulator.includes('> '),
+  `say1 output does not include prompt: "${output.accumulator}"`,
+);
+
+await run(['.say2 node developer\n']);
+assert.ok(
+  output.accumulator.startsWith('hello from say2\n'),
+  `say2 output starts incorrectly: "${output.accumulator}"`,
+);
+assert.ok(
+  output.accumulator.includes('> '),
+  `say2 output does not include prompt: "${output.accumulator}"`,
+);
+
+replServer.close();