Manual URL manipulation leads to invalid results.

The test was working by accident on UNIX - with an absolute path the
beginning of the string would be file:///, which is the expected prefix.
On Windows though the result was an invalid URL. Use the platform
provided functionality to construct the URL and remove invalid
statement in the comment.
No manual path construction.

Use the correct constructor to create a child path.
Zip entries use UNIX style (relative) paths by standard.

Why the leading dot though?
No echo executable on Windows.

There is no echo executable on Windows, it is a command
provided by the shell. To test the process builder we need
OS-specific commands. The alternative is to include shell
scripts for both UNIX and Windows and call them with an
uniform command.
Fix check for Windows OS.

The format is "Windows XX", no microsoft in the name.