(#11714) Use `%~dp0` to resolve bat file's install directory

This commit uses the `%~dp0` batch script modifier to resolve the
drive and path of the directory containing the envpuppet.bat
file. This eliminates the need for hard coded paths within the script
itselfIt also uses `%VAR:\=/%` to substitute each backslash for a
forward slash in the RUBYLIB environment

Also added a section about running the spec tests on Windows.

Reviewed-By: Jeff McCune <jeff@puppetlabs.com>

README_DEVELOPER.md

@@ -62,10 +62,9 @@ SyntaxError, invalid multibyte escape as mentioned above.
 
 # Windows #
 
-If you'd like to run Puppet from source on Windows platforms, the include
-`ext/envpuppet.bat` will help.  NOTE: the RUBYLIB environment variable must
-have forward slashes (/) rather than Windows back slashes.  All file paths in
-the Puppet code base should use a path separator of / regardless of Windows or
+If you'd like to run Puppet from source on Windows platforms, the
+include `ext/envpuppet.bat` will help.  All file paths in the Puppet
+code base should use a path separator of / regardless of Windows or
 Unix filesystem.
 
 To quickly run Puppet from source, assuming you already have Ruby installed
@@ -75,11 +74,17 @@ from [rubyinstaller.org](http://rubyinstaller.org).
     gem install win32-service --platform=mswin32 --no-rdoc --no-ri --version 0.7.1
     net use Z: "\\vmware-host\Shared Folders" /persistent:yes
     Z:
-    cd \
-    cd \vagrant\src\puppet\ext
+    cd <path_to_puppet>
+    set PATH=%PATH%;Z:\<path_to_puppet>\ext
     envpuppet puppet --version
     2.7.9
 
+Some spec tests are known to fail on Windows, e.g. no mount provider
+on Windows, so use the following rspec exclude filter:
+
+    cd <path_to_puppet>
+    envpuppet rspec --tag ~fails_on_windows spec
+
 This will give you a shared filesystem with your Mac and allow you to run
 Puppet directly from source without using install.rb or copying files around.
 

ext/envpuppet.bat

@@ -3,8 +3,11 @@ SETLOCAL
 
 REM net use Z: "\\vmware-host\Shared Folders" /persistent:yes
 
-SET RUBYLIB=Z:/vagrant/src/facter/lib;Z:/vagrant/src/puppet/lib;%RUBYLIB%
-SET PATH=Z:/vagrant/src/facter/bin;Z:/vagrant/src/puppet/bin;%PATH%
+SET PUPPET_DIR=%~dp0..
+SET FACTER_DIR=%PUPPET_DIR%\..\facter
+
+SET PATH=%PUPPET_DIR%\bin;%FACTER_DIR%\bin;%PATH%
+SET RUBYLIB=%PUPPET_DIR%\lib;%FACTER_DIR%\lib;%RUBYLIB%
+SET RUBYLIB=%RUBYLIB:\=/%
 
 ruby -S %*
-