From e108eb0d3620133b766deb57d6c1852cc78a6d7c Mon Sep 17 00:00:00 2001
From: Tomas <trylek@microsoft.com>
Date: Mon, 18 Apr 2022 21:31:55 +0200
Subject: [PATCH] Improve performance of test partitioning

I have noticed a perf bug I made as part of the refactoring for
merged test wrapper support. When there are no merged wrappers
available due to test filtering (using the test / dir / tree
commands-line argument), %(MergedAssemblyParentFolders.Identity)
expands to an empty string at line 397 and AllRunnablePaths
effectively search the entire HDD for tests to remove. In my
case it reduced the running time of GetListOfTestCmds from 23
minutes to 3 milliseconds.

Thanks

Tomas
---
 src/tests/build.proj | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/tests/build.proj b/src/tests/build.proj
index 78700b40b7c7f2..879d27c1f215d5 100644
--- a/src/tests/build.proj
+++ b/src/tests/build.proj
@@ -394,12 +394,12 @@
       <MergedAssemblyMarkerPaths Include="$(XunitTestBinBase)\**\*.MergedTestAssembly"/>
       <MergedAssemblyFolders Include="$([System.IO.Path]::GetDirectoryName('%(MergedAssemblyMarkerPaths.Identity)'))" />
       <MergedAssemblyParentFolders Include="$([System.IO.Path]::GetDirectoryName('%(MergedAssemblyFolders.Identity)'))" />
-      <AllRunnableTestPaths Remove="%(MergedAssemblyParentFolders.Identity)\**\*.$(TestScriptExtension)" />
-      <MergedRunnableTestPaths Include="$([System.IO.Path]::ChangeExtension('%(MergedAssemblyMarkerPaths.Identity)', '.$(TestScriptExtension)'))" />
+      <AllRunnableTestPaths Remove="%(MergedAssemblyParentFolders.Identity)\**\*.$(TestScriptExtension)" Condition="'@(MergedAssemblyParentFolders)' != ''" />
+      <MergedRunnableTestPaths Include="$([System.IO.Path]::ChangeExtension('%(MergedAssemblyMarkerPaths.Identity)', '.$(TestScriptExtension)'))" Condition="'@(MergedAssemblyMarkerPaths)' != ''" />
       <OutOfProcessTestMarkerPaths Include="$(XunitTestBinBase)\**\*.OutOfProcessTest"/>
-      <OutOfProcessTestPaths Include="$([System.IO.Path]::ChangeExtension('%(OutOfProcessTestMarkerPaths.Identity)', '.$(TestScriptExtension)'))" />
+      <OutOfProcessTestPaths Include="$([System.IO.Path]::ChangeExtension('%(OutOfProcessTestMarkerPaths.Identity)', '.$(TestScriptExtension)'))" Condition="'@(OutOfProcessTestMarkerPaths)' != ''" />
       <NoMonoAotMarkerPaths Include="$(XunitTestBinBase)\**\*.NoMonoAot" />
-      <NoMonoAotAssemblyPaths Include="$([System.IO.Path]::ChangeExtension('%(NoMonoAotMarkerPaths.Identity)', '.dll'))" />
+      <NoMonoAotAssemblyPaths Include="$([System.IO.Path]::ChangeExtension('%(NoMonoAotMarkerPaths.Identity)', '.dll'))" Condition="'@(NoMonoAotMarkerPaths)' != ''" />
     </ItemGroup>
     <!-- Remove the cmd/sh scripts for merged test runner app bundles from our list. -->
     <PropertyGroup Condition="'$(TargetsMobile)' == 'true'">