@ECHO OFF
IF "%1" == "TEST_EOF" (
  GOTO :EOF
) ELSE IF "%1" == "TEST_EXPANSION" (
  SET extensions=enabled
  IF "!extensions!"=="enabled" (
    ECHO  Delayed environment variable expansion = ON
  ) ELSE (
    ECHO  Delayed environment variable expansion = OFF
  )
) ELSE IF "%1" == "TEST_EXTENSIONS" (
  :: CALL :label is not available if test extensions are disabled.
  CALL %0 TEST_EOF 2>nul
  IF NOT ERRORLEVEL 1 (
    ECHO  Command extensions                     = ON
  ) ELSE (
    ECHO  Command extensions                     = OFF
  )
) ELSE (
  ECHO == Default ==
    CALL %0 TEST_EXPANSION
    CALL %0 TEST_EXTENSIONS
  ECHO.
  
  ECHO == Enabled ==
    SETLOCAL ENABLEDELAYEDEXPANSION ENABLEEXTENSIONS
    CALL %0 TEST_EXPANSION
    CALL %0 TEST_EXTENSIONS
    ENDLOCAL
  ECHO.
  
  ECHO == Disabled ==
    SETLOCAL DISABLEDELAYEDEXPANSION DISABLEEXTENSIONS
    CALL %0 TEST_EXPANSION
    CALL %0 TEST_EXTENSIONS
    ENDLOCAL
)