Repository: nodejs/node
Pull request: doc: update example of using `await` in REPL

> [!Note]
> I'm just trying to do a bit of caretaking here and trying to resolve this stalled PR: https://github.com/nodejs/node/pull/45939
> credit to the original author @deokjinkim :slightly_smiling_face: 

Clarify that the lexical scope of `const` is
invalidated when using top-level `await` in REPL.

As part of this change also add tests for the
documented behavior

Fixes: https://github.com/nodejs/node/issues/45918


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Changed files:
filename: doc/api/repl.md
patch: @@ -258,8 +258,7 @@ undefined
 ```
 
 One known limitation of using the `await` keyword in the REPL is that
-it will invalidate the lexical scoping of the `const` and `let`
-keywords.
+it will invalidate the lexical scoping of the `const` keywords.
 
 For example:
 
@@ -268,10 +267,11 @@ For example:
 undefined
 > m
 123
-> const m = await Promise.resolve(234)
-undefined
-> m
+> 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
 ```
 
 [`--no-experimental-repl-await`][] shall disable top-level await in REPL.

filename: test/parallel/test-repl-top-level-await.js
patch: @@ -173,6 +173,12 @@ async function ordinaryTests() {
       '3',
       'undefined',
     ]],
+    // Testing documented behavior of `const`s (see: https://github.com/nodejs/node/issues/45918)
+    ['const k = await Promise.resolve(123)'],
+    ['k', '123'],
+    ['k = await Promise.resolve(234)', '234'],
+    ['k', '234'],
+    ['const k = await Promise.resolve(345)', "Uncaught SyntaxError: Identifier 'k' has already been declared"],
     // Regression test for https://github.com/nodejs/node/issues/43777.
     ['await Promise.resolve(123), Promise.resolve(456)', 'Promise {', { line: 0 }],
     ['await Promise.resolve(123), await Promise.resolve(456)', '456'],