Add Read-Host regression test

test/powershell/Host/Read-Host.Tests.ps1

@@ -0,0 +1,20 @@
+Describe "Read-Host" {
+    Context "[Console]::ReadKey() implementation on non-Windows" {
+        BeforeAll {
+            $powershell = Join-Path -Path $PsHome -ChildPath "powershell"
+            $assetsDir = Join-Path -Path $PSScriptRoot -ChildPath assets
+            if ($IsWindows) {
+                $ItArgs = @{ skip = $true }
+            } elseif (-not (Get-Command expect -ErrorAction Ignore)) {
+                $ItArgs = @{ pending = $true }
+            } else {
+                $ItArgs = @{ }
+            }
+        }
+
+        It @ItArgs "Should output correctly" {
+            & (Join-Path $assetsDir "Read-Host.Output.expect") $powershell | Out-Null
+            $LASTEXITCODE | Should Be 0
+        }
+    }
+}

test/powershell/Host/assets/Read-Host.Output.expect

@@ -0,0 +1,27 @@
+#!/usr/bin/expect -f
+
+exp_internal 1
+
+# Expects path to PowerShell as first argument
+set powershell [lindex $argv 0]
+
+set timeout 5
+
+spawn $powershell -nologo -noprofile Read-Host prompt
+
+expect "prompt: $" {
+    send "input\r"
+}
+
+# This is the old, incorrect behavior
+expect "input\r\ninput\r" {
+    exit 2
+}
+
+# This is the expected behavior
+expect "input\r\n" {
+    exit 0
+}
+
+# Anything else is wrong
+exit 1