How do you do negative Lookahead/Lookbehind in the gitignore files?

I am using git for a project and want to exclude a specific subfolder from a path but not the siblings of that folder For example:

/Testpath/TestpathA
/Te开发者_开发问答stpath/TestpathB
/Testpath/TestpathC

I want to ignore TestpathA and C (and any other paths that may be siblings of those folders, but not TestpathB

I tried

/Testpath/*
!/Testpath/TestpathB

but that didn't work.

I also tried /Testpath/(?!TestpathB)/*

but that didn't work either.

---

How about;

Testpath/*
!Testpath/TestpathB

Edit: Actually, strike that, your example works just fine for me as well. What exactly is it you are doing that isn't working? Besides creating the .gitignore, what commands are you running?

---

Using

/Testpath/*
!/Testpath/TestpathB

worked for me:

→ cat .gitignore
/Testpath/*
!/Testpath/TestpathB

→ tree
.
└── Testpath
    ├── TestpathA
    │   └── testfile
    ├── TestpathB
    │   └── testfile
    └── TestpathC
        └── testfile

4 directories, 3 files

→ git status
# On branch master
#
# Initial commit
#
# Untracked files:
#   (use "git add <file>..." to include in what will be committed)
#
#       .gitignore
#       Testpath/
nothing added to commit but untracked files present (use "git add" to track)

→ git add .

→ git status
# On branch master
#
# Initial commit
#
# Changes to be committed:
#   (use "git rm --cached <file>..." to unstage)
#
#       new file:   .gitignore
#       new file:   Testpath/TestpathB/testfile
#