I think you have a typo, too many forward slashes:
git clone file:////usr/local/git_root/gitTest.git
should be
git clone file:///usr/local/git_root/gitTest.git
Alternatively,
git clone /usr/local/git_root/gitTest.git
Edit:
For posterity, the comment above alludes to the fact that the cloning user needs to have root access to the folder.