MenuComplete behaves oddly in folder with many (>50) items

[MartinSGill]

Prerequisites

• Write a descriptive title.
• Make sure you are able to repro it on the latest released version
• Search the existing issues, especially the pinned issues.

Exception report

N/A

Screenshot

Environment data

PS Version: 7.3.0-preview.4
PS HostName: ConsoleHost (Windows Terminal)
PSReadLine Version: 2.2.2
PSReadLine EditMode: Windows
OS: 10.0.19041.1 (WinBuild.160101.0800)
BufferWidth: 122
BufferHeight: 29

Steps to reproduce

Create many sub-folders (or files), e.g.

@(1..60) | % { mkdir Some.Very.Very.Very.Very.Long.Prefix.Folder.With$_ }

Set MenuComplete as handler

Set-PSReadLineKeyHandler -Key Tab -Function MenuComplete

Type: ls Som<TAB>

Expected behavior

Same as when

Set-PSReadLineKeyHandler -Key Tab -Function Complete

i.e.

Current text at cursor updated to Some.Very.Very.Very.Very.Long.Prefix.Folder.With

Actual behavior

A list of folders is displayed (no menu) and the text at the cursor is not updated.

Presumably, there is too much data to render a menu and MenuComplete tries to fall back to the Complete function, but it seems to not do this correctly.

I would expect the text at cursor to be updated to the longest unique value (as described in the docs)

[daxian-dbw]

This is the by design behavior. It's not falling back to Complete, but falling back to the "Display all xxx possibilities? (y or n)" UI, which is also used by Complete. For Complete, the step that completes to the longest unique sub-string is done before getting to the "Display all possibilities" UI.