Address code review feedback

build-test.cmd

@@ -9,7 +9,7 @@ set __BuildOS=Windows_NT
 
 :: Define a prefix for most output progress messages that come from this script. That makes
 :: it easier to see where these are coming from. Note that there is a trailing space here.
-set __MsgPrefix=BUILDTEST: 
+set "__MsgPrefix=BUILDTEST: "
 
 :: Default to highest Visual Studio version available
 ::
@@ -33,7 +33,7 @@ if defined VisualStudioVersion (
 
 set _VSWHERE="%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe"
 if exist %_VSWHERE% (
-  for /f "usebackq tokens=*" %%i in (`%_VSWHERE% -latest -property installationPath`) do set _VSCOMNTOOLS=%%i\Common7\Tools
+  for /f "usebackq tokens=*" %%i in (`%_VSWHERE% -latest -prerelease -property installationPath`) do set _VSCOMNTOOLS=%%i\Common7\Tools
 )
 if not exist "%_VSCOMNTOOLS%" set _VSCOMNTOOLS=%VS140COMNTOOLS%
 if not exist "%_VSCOMNTOOLS%" (
@@ -123,8 +123,6 @@ if defined __BuildAgainstPackagesArg (
     )
 )
 
-:: echo %__MsgPrefix%Using environment: "%__VSToolsRoot%\VsDevCmd.bat"
-:: call                                 "%__VSToolsRoot%\VsDevCmd.bat"
 @if defined _echo @echo on
 
 set __RunArgs=-BuildOS=%__BuildOS% -BuildType=%__BuildType% -BuildArch=%__BuildArch%

run.cmd

@@ -23,11 +23,11 @@ if defined VisualStudioVersion (
 
 set _VSWHERE="%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe"
 if exist %_VSWHERE% (
-  for /f "usebackq tokens=*" %%i in (`%_VSWHERE% -latest -property installationPath`) do set _VSCOMNTOOLS=%%i\Common7\Tools
+  for /f "usebackq tokens=*" %%i in (`%_VSWHERE% -latest -prerelease -property installationPath`) do set _VSCOMNTOOLS=%%i\Common7\Tools
 )
 if not exist "%_VSCOMNTOOLS%" set _VSCOMNTOOLS=%VS140COMNTOOLS%
 if not exist "%_VSCOMNTOOLS%" (
-  echo Error: Visual Studio 2015 or 2017 required.
+  echo %__MsgPrefix%Error: Visual Studio 2015 or 2017 required.
   echo        Please see https://github.com/dotnet/corefx/blob/master/Documentation/project-docs/developer-guide.md for build instructions.
   exit /b 1
 )

tests/runtest.cmd

@@ -33,7 +33,7 @@ if defined VisualStudioVersion (
 
 set _VSWHERE="%ProgramFiles(x86)%\Microsoft Visual Studio\Installer\vswhere.exe"
 if exist %_VSWHERE% (
-  for /f "usebackq tokens=*" %%i in (`%_VSWHERE% -latest -property installationPath`) do set _VSCOMNTOOLS=%%i\Common7\Tools
+  for /f "usebackq tokens=*" %%i in (`%_VSWHERE% -latest -prerelease -property installationPath`) do set _VSCOMNTOOLS=%%i\Common7\Tools
 )
 if not exist "%_VSCOMNTOOLS%" set _VSCOMNTOOLS=%VS140COMNTOOLS%
 if not exist "%_VSCOMNTOOLS%" (
@@ -159,10 +159,6 @@ if not exist "%__VSToolsRoot%\VsDevCmd.bat"           goto NoVS
 :: Does MSBuild really exist?
 if not exist %_msbuildexe% echo %__MsgPrefix%Error: Could not find MSBuild.exe.  Please see https://github.com/dotnet/coreclr/blob/master/Documentation/project-docs/developer-guide.md for build instructions. && exit /b 1
 
-:: Set the environment for the  build- VS cmd prompt
-:: echo %__MsgPrefix%Using environment: "%__VSToolsRoot%\VsDevCmd.bat"
-:: call                                 "%__VSToolsRoot%\VsDevCmd.bat"
-
 if not defined VSINSTALLDIR (
     echo %__MsgPrefix%Error: runtest.cmd should be run from a Visual Studio Command Prompt.  Please see https://github.com/dotnet/coreclr/blob/master/Documentation/project-docs/developer-guide.md for build instructions.
     exit /b 1
@@ -331,7 +327,7 @@ if %__exitCode% neq 0 (
     exit /b 0
 )
 
-echo Successfully precompiled %2
+echo %__MsgPrefix%Successfully precompiled %2
 exit /b 0
 
 :jitdisasm
@@ -385,7 +381,7 @@ set __msbuildLogArgs=^
 set __msbuildArgs=%* %__msbuildCommonArgs% %__msbuildLogArgs%
 
 @REM The next line will overwrite the existing log file, if any.
-echo %_msbuildexe% %__msbuildArgs%
+echo %__MsgPrefix%%_msbuildexe% %__msbuildArgs%
 echo Invoking: %_msbuildexe% %__msbuildArgs% > "%__BuildLog%"
 
 %_msbuildexe% %__msbuildArgs%