[MXC] Add checks and fixes for Python and App Execution Aliases by huzaifa-d · Pull Request #326 · microsoft/mxc

huzaifa-d · 2026-05-15T22:56:44Z

Description

E2E tests failed with cryptic errors (exit 9009, CreateProcessW 0x80070057) when Python was missing/per-user or Windows Store App Execution Aliases shadowed real executables. Store reparse points cannot be launched inside AppContainer/BaseContainer sandboxes.

Changes:

build.bat: post-build prereq warnings with interactive fix (install Python via winget + remove Store aliases) when running elevated; opens a fresh terminal after fix for PATH to take effect
src/wxc/build.rs: emit cargo:warning during compilation when Python/pwsh are missing or resolve to Store aliases
src/wxc_e2e_tests: assert_python()/assert_pwsh() fail tests with clear remediation messages instead of cryptic exit codes; checks if any non-Store path exists (not just the first)
test_configs/basic_lpac.json: fix import sys being inside print() string literal
test_configs/pwsh_setlocation.json: use full path for pwsh.exe, remove hardcoded C:\Users\st path
scripts/setup-test-prereqs.ps1: standalone elevated setup script for one-time machine setup

References

Closes #323

Validation

Tested on ARM64 Windows (build 26617) via SSH and interactive terminal
Verified: build warnings appear during cargo build
Verified: build.bat detects missing Python/Store aliases, prompts to fix when elevated, opens fresh terminal
Verified: tests fail with clear message when Python missing, pass after fix
Verified: pwsh_setlocation passes with full path in config
All 14 E2E tests pass after prerequisites are installed

Checklist

Signed the Contributor License Agreement
Linked to an issue
Updated documentation (if applicable)
Updated Copilot instructions (if build, architecture, or conventions changed)

Issue Type

Bug fix
Feature
Task

Microsoft Reviewers: Open in CodeFlow

…E2E tests E2E tests failed with cryptic errors (exit 9009, CreateProcessW 0x80070057) when Python was missing/per-user or Windows Store App Execution Aliases shadowed real executables. Store reparse points cannot be launched inside AppContainer/BaseContainer sandboxes. Changes: - build.bat: add post-build prereq warnings with interactive fix (install Python via winget + remove Store aliases) when running elevated - build.rs (wxc): emit cargo:warning during compilation when Python/pwsh are missing or resolve to Store aliases - wxc_e2e_tests: add assert_python()/assert_pwsh() that fail tests with clear remediation messages instead of cryptic exit codes - test_configs/basic_lpac.json: fix import sys being inside print() string - test_configs/pwsh_setlocation.json: use full path for pwsh.exe, remove hardcoded C:\Users\st path - scripts/setup-test-prereqs.ps1: standalone elevated setup script Closes #323 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- build.bat: only warn when ALL python/pwsh matches are Store aliases (no false positive when real install coexists); remove duplicate ALIAS_ISSUE assignment; apply same logic to pwsh check - build.rs: add cargo:rerun-if-env-changed=PATH so warnings update after installing Python/PowerShell - lib.rs: use case-insensitive check (to_ascii_lowercase) for WindowsApps detection in assert_python() and assert_pwsh() Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

- assert_python: fail when *first* PATH match is a Store alias (shadowing), not just when all matches are aliases — matches actual sandbox behavior - assert_pwsh: validate hardcoded C:\Program Files\PowerShell\7\pwsh.exe path exists instead of generic where.exe check - build.bat: detect first-match Store alias shadowing for python.exe; simplified pwsh check to validate expected install path - setup-test-prereqs.ps1: use Get-Command -All to find any real Python even when Store alias shadows it; check \0 after winget install; handle missing winget gracefully Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 6 comments.

SohamDas2021 · 2026-05-18T22:16:16Z

+if "!PYTHON_FIRST_ALIAS!"=="1" (
+    echo   WARNING: python.exe first resolves to a Store alias.
+    echo            Store aliases shadow real installs and cannot be launched inside sandbox containers.
+    set "PREREQ_WARN=1"
+    set "PYTHON_MISSING=1"
+    set "ALIAS_ISSUE=1"
+)


Is this one valid?

+set /p "FIX_ALL=  Fix issues and install Python? [Y/n] "
+if /i "!FIX_ALL!"=="n" goto :done
+
+if "%PYTHON_MISSING%"=="1" (
+    echo   Installing Python 3.12 via winget...
+    winget install Python.Python.3.12 --scope machine --accept-package-agreements --accept-source-agreements
+)
+
+if "%ALIAS_ISSUE%"=="1" (
+    echo   Removing Store aliases...
+    if exist "%LOCALAPPDATA%\Microsoft\WindowsApps\python.exe"  del /f "%LOCALAPPDATA%\Microsoft\WindowsApps\python.exe"  2>nul && echo     Removed python.exe alias
+    if exist "%LOCALAPPDATA%\Microsoft\WindowsApps\python3.exe" del /f "%LOCALAPPDATA%\Microsoft\WindowsApps\python3.exe" 2>nul && echo     Removed python3.exe alias
+    if exist "%LOCALAPPDATA%\Microsoft\WindowsApps\pwsh.exe"    del /f "%LOCALAPPDATA%\Microsoft\WindowsApps\pwsh.exe"    2>nul && echo     Removed pwsh.exe alias
+)
+
+echo.
+echo   Prerequisites fixed. Starting a fresh terminal to pick up PATH changes...
+echo.
+start cmd /k "cd /d %~dp0 && echo Ready. Run your tests now."
+


+    // Check pwsh
+    let pwsh_ok = Command::new("where.exe")
+        .arg("pwsh.exe")
+        .output()
+        .ok()
+        .and_then(|o| {
+            if !o.status.success() {
+                return None;
+            }
+            let stdout = String::from_utf8_lossy(&o.stdout).to_string();
+            let first = stdout.lines().next().unwrap_or("").to_string();
+            Some(first)
+        });
+
+    match pwsh_ok {
+        None => {
+            println!("cargo:warning=pwsh.exe not found. PowerShell 7 sandbox tests will fail.");
+            println!(
+                "cargo:warning=Fix: Run scripts\\setup-test-prereqs.ps1 (elevated) or install PowerShell 7"
+            );
+        }
+        Some(ref path) if path.to_ascii_lowercase().contains("windowsapps") => {
+            println!("cargo:warning=pwsh.exe resolves to a Store alias. Store aliases cannot be launched inside sandbox containers.");
+            println!(
+                "cargo:warning=Fix: Run scripts\\setup-test-prereqs.ps1 (elevated) or disable App Execution Aliases for PowerShell"
+            );
+        }
+        _ => {}
+    }


+$pwshReal = Get-Command pwsh.exe -All -ErrorAction SilentlyContinue | 
+    Where-Object { $_.Source -notlike "*WindowsApps*" } | 
+    Select-Object -First 1
+if ($pwshReal) {
+    Write-Host " OK ($($pwshReal.Source))" -ForegroundColor Green
+} else {
+    Write-Host " MISSING (no non-Store pwsh.exe found)" -ForegroundColor Red
+    $issues += "PowerShell 7 is not installed (or only available via Store alias)."


+/// Check whether `python.exe` is available and the *first* match in PATH
+/// is NOT a Windows Store App Execution Alias. Store aliases are reparse
+/// points under `WindowsApps` that cannot be launched inside
+/// AppContainer/BaseContainer sandboxes. Even when a real Python exists
+/// later in PATH, the sandbox will try to launch the first match and fail.
+///
+/// Panics with a clear remediation message when Python is missing or
+/// the first PATH match is a Store alias.
+pub fn assert_python() {
+    let output = Command::new("where.exe").arg("python.exe").output().ok();
+
+    let Some(output) = output else {
+        panic!(
+            "python.exe not found.\n\
+             E2E tests require a system-wide Python install.\n\
+             Fix: Run scripts\\setup-test-prereqs.ps1 (elevated) or install Python system-wide \
+             (winget install Python.Python.3.12 --scope machine)"
+        );
+    };
+
+    if !output.status.success() {
+        panic!(
+            "python.exe not found.\n\
+             E2E tests require a system-wide Python install.\n\
+             Fix: Run scripts\\setup-test-prereqs.ps1 (elevated) or install Python system-wide \
+             (winget install Python.Python.3.12 --scope machine)"
+        );
+    }
+
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    let first_path = stdout.lines().next().unwrap_or("");
+    if first_path.to_ascii_lowercase().contains("windowsapps") {
+        panic!(
+            "python.exe first resolves to a Windows Store alias ({first_path}).\n\
+             Store aliases shadow real installs and cannot be launched inside sandbox containers.\n\
+             Fix: Run scripts\\setup-test-prereqs.ps1 (elevated) or disable App Execution Aliases for Python"
+        );
+    }


+    $userAlias = Join-Path $env:LOCALAPPDATA "Microsoft\WindowsApps\$ExeName"
+    if (Test-Path $userAlias) {
+        Remove-Item $userAlias -Force -ErrorAction SilentlyContinue
+        Write-Host "  Disabled user alias: $userAlias" -ForegroundColor Green


- build.bat: check winget exists before invoking; report if install fails - build.rs: check pwsh at hardcoded C:\Program Files\PowerShell\7\pwsh.exe instead of where.exe (matches test config and assert_pwsh) - setup-test-prereqs.ps1: check pwsh at expected install path instead of Get-Command PATH lookup (consistent with test config) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jsidewhite · 2026-05-18T22:15:18Z

+    # Removing them from the user-local path disables the alias for the current user.
+    $userAlias = Join-Path $env:LOCALAPPDATA "Microsoft\WindowsApps\$ExeName"
+    if (Test-Path $userAlias) {
+        Remove-Item $userAlias -Force -ErrorAction SilentlyContinue


Remove

as long as it's understood that updates may restore the behavior, and this will nuke aliases from legitimate packaged python (i.e. this is for test machines only)

…Test-StoreAlias Per Jeff's feedback (PR #326): - build.bat: remove all interactive fix logic (winget install, alias removal, terminal restart). build.bat is for dev machines; nuking aliases there is inappropriate. It now just emits warnings + a pointer to scripts\setup-test-prereqs.ps1 for test machines. - setup-test-prereqs.ps1: simplify Test-StoreAlias to just check %LOCALAPPDATA%\Microsoft\WindowsApps\<exe> (the redundant AppData subset clause is gone). Disable-StoreAlias now documents that: 1. This is intended for TEST MACHINES ONLY. 2. Deleting the reparse point IS the Windows-documented mechanism to disable an alias (per AppAliasListItemSetting::SetValue in onecore/base/appmodel/AppExecutionAlias/settingshandlers). 3. Updates may restore aliases. Verified via Windows OS source (Os.2020 br_current). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jsidewhite · 2026-05-19T21:36:55Z

+    for /f "tokens=*" %%P in ('where python.exe') do (
+        echo %%P | findstr /i "WindowsApps" >nul 2>&1
+        if not errorlevel 1 (
+            echo   WARNING: python.exe first resolves to a Store alias.


Store

"MSIX AppModel" alias

you haven't checked whether or not it's the store alias.

jsidewhite · 2026-05-19T21:37:49Z

+    echo   All E2E test prerequisites met.
+) else (
+    echo.
+    echo   To fix, run from an elevated PowerShell prompt:


echo

can you write to standard WARN or make it yellow (i'm not sure in .bat)?

jsidewhite · 2026-05-19T21:39:32Z

+    echo   All E2E test prerequisites met.
+) else (
+    echo.
+    echo   To fix, run from an elevated PowerShell prompt:


fix

to "disable the alias"

jsidewhite · 2026-05-19T21:40:21Z

+            Remove-Item $userAlias -Force -ErrorAction Stop
+            Write-Host "  Disabled user alias: $userAlias" -ForegroundColor Green
+        } catch {
+            Write-Host "  WARNING: failed to remove $userAlias`: $($_.Exception.Message)" -ForegroundColor Yellow


Write-Host

Write-Warning?

jsidewhite · 2026-05-19T21:40:43Z

+# Fix: Disable Store aliases
+foreach ($exe in @("python.exe", "python3.exe", "pwsh.exe")) {
+    if (Test-StoreAlias $exe) {
+        Write-Host "Disabling Store alias for $exe..." -ForegroundColor Cyan


Store

should not say "store"

- build.bat: check the exact App Execution Alias reparse point path (%LOCALAPPDATA%\Microsoft\WindowsApps\python.exe) instead of any substring containing 'WindowsApps'. Reword 'fix' -> 'install Python and disable the alias'. - setup-test-prereqs.ps1: rename Test-StoreAlias/Disable-StoreAlias to Test-AppExecutionAlias/Disable-AppExecutionAlias. Replace all 'Store alias' wording with 'App Execution Alias'. Use Write-Warning instead of Write-Host for warnings. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

jsidewhite

Copilot AI review requested due to automatic review settings May 15, 2026 22:56

huzaifa-d added Issue-Bug Something isn't working Needs-Triage labels May 15, 2026

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huzaifa-d marked this pull request as ready for review May 18, 2026 18:48

huzaifa-d changed the title ~~fix(test): add prereq checks for Python and App Execution Aliases in E2E tests~~ [MXC] Add checks and fixes for Python and App Execution Aliases May 18, 2026

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huzaifa-d merged commit e042115 into main May 19, 2026
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huzaifa-d deleted the feat/test-prereq-checks branch May 19, 2026 22:27

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Description

References

Validation

Checklist

Issue Type

Microsoft Reviewers: Open in CodeFlow

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