From 0411abd580703ed806924f8bd1300e532a9ab194 Mon Sep 17 00:00:00 2001
From: AmirMS <104940545+AmelBawa-msft@users.noreply.github.com>
Date: Tue, 23 Jun 2026 14:39:40 -0700
Subject: [PATCH] Update build

---
 .pipelines/build-job.yml         |  2 +-
 test/windows/wslc/CMakeLists.txt | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/.pipelines/build-job.yml b/.pipelines/build-job.yml
index f883f0b4bb..6ace42272b 100644
--- a/.pipelines/build-job.yml
+++ b/.pipelines/build-job.yml
@@ -124,7 +124,7 @@ jobs:
         displayName: "CMake ${{ parameters.platform }}"
         inputs:
           workingDirectory: "."
-          cmakeArgs: . --fresh -A ${{ parameters.platform }} -DCMAKE_BUILD_TYPE=Release -DCMAKE_SYSTEM_VERSION=10.0.26100.0 -DPACKAGE_VERSION=$(version.WSL_PACKAGE_VERSION) -DWSL_NUGET_PACKAGE_VERSION=$(version.WSL_NUGET_PACKAGE_VERSION) -DSKIP_PACKAGE_SIGNING=${{ parameters.isRelease }} -DOFFICIAL_BUILD=${{ parameters.isRelease }} -DINCLUDE_PACKAGE_STAGE=${{ or(parameters.isRelease, parameters.isNightly) }} -DPIPELINE_BUILD_ID=$(Build.BuildId) -DVSO_ORG=${{ parameters.vsoOrg }} -DVSO_PROJECT=${{ parameters.vsoProject }} -DWSL_BUILD_WSL_SETTINGS=true -DWSL_INCLUDE_SDK_CSHARP=true $(packageInputDirArg)\${{ parameters.platform }}
+          cmakeArgs: . --fresh -A ${{ parameters.platform }} -DCMAKE_BUILD_TYPE=Release -DCMAKE_SYSTEM_VERSION=10.0.26100.0 -DPACKAGE_VERSION=$(version.WSL_PACKAGE_VERSION) -DWSL_NUGET_PACKAGE_VERSION=$(version.WSL_NUGET_PACKAGE_VERSION) -DSKIP_PACKAGE_SIGNING=${{ parameters.isRelease }} -DOFFICIAL_BUILD=${{ parameters.isRelease }} -DINCLUDE_PACKAGE_STAGE=${{ or(parameters.isRelease, parameters.isNightly) }} -DPIPELINE_BUILD_ID=$(Build.BuildId) -DVSO_ORG=${{ parameters.vsoOrg }} -DVSO_PROJECT=${{ parameters.vsoProject }} -DWSL_BUILD_WSL_SETTINGS=true -DWSL_INCLUDE_SDK_CSHARP=true -DWSL_E2E_UNITY_BUILD=ON $(packageInputDirArg)\${{ parameters.platform }}
 
       # Workaround for WSL Settings NuGet restore authentication issue
       - script: _deps\nuget.exe restore -NonInteractive
diff --git a/test/windows/wslc/CMakeLists.txt b/test/windows/wslc/CMakeLists.txt
index 23418d7cbc..4dbc6acc39 100644
--- a/test/windows/wslc/CMakeLists.txt
+++ b/test/windows/wslc/CMakeLists.txt
@@ -18,6 +18,26 @@ set_source_files_properties(${WSLC_TEST_SOURCES}
     COMPILE_FLAGS "/Yuprecomp.h"
 )
 
+# Opt-in unity build for the e2e tests (~2x faster clean recompile; CI enables it).
+option(WSL_E2E_UNITY_BUILD "Unity-batch the wslc e2e test sources" OFF)
+set(WSL_E2E_UNITY_BATCH_SIZE 8 CACHE STRING "Unity batch size for wslc e2e tests")
+
+if(WSL_E2E_UNITY_BUILD)
+    # GROUP mode only batches sources tagged with UNITY_GROUP, so tag e2e sources and leave every other wsltests source untouched.
+    set_target_properties(wsltests PROPERTIES UNITY_BUILD ON UNITY_BUILD_MODE GROUP)
+
+    file(GLOB WSLC_E2E_SOURCES CONFIGURE_DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/e2e/*.cpp)
+    set(_e2eIndex 0)
+    foreach(_e2eSource IN LISTS WSLC_E2E_SOURCES)
+        math(EXPR _e2eGroup "${_e2eIndex} / ${WSL_E2E_UNITY_BATCH_SIZE}")
+        set_source_files_properties(${_e2eSource}
+            TARGET_DIRECTORY wsltests
+            PROPERTIES UNITY_GROUP "wslc_e2e_${_e2eGroup}"
+        )
+        math(EXPR _e2eIndex "${_e2eIndex} + 1")
+    endforeach()
+endif()
+
 # Add include directories needed for WSLC tests.
 target_include_directories(wsltests PRIVATE
     ${CMAKE_SOURCE_DIR}/test