I believe you are missing a

chattr +P -p 51 /test/first

/etc/projects seems only used by XFS tools. Also /etc/projid is only there for pretty printing.

fyi this is the procedure I came up with:

(step 0 to actually create the block device:

dd if=/dev/zero of=/tmp/fs bs=1024 count=80000
losetup -f /tmp/fs
losetup -l

)

1. create a file system with big enough inodes:

mkfs.ext4 -I 256 /dev/loop0

2. enable project quotas and make sure the file system is mounted with it by default (here using extended options with -E, avoiding the mount option in your step3, but also quite sneaky as you don't see it in /proc/mounts as mounted as such)

tune2fs -Q prjquota  /dev/loop0
tune2fs -E mount_opts=prjquota /dev/loop0

3. mount it

mount /dev/loop0 /mnt/loop/

4. the quota on command does not seem useful, so skipping this one

5. set a proj id, but as a pure courtesy for the next sys admin logging in to your box. Not actually required

echo testproj:51 >> /etc/projid

6. actually make your folder part of the project (which was missing from your list)

mkdir abc
chattr +P -p 51 abc

7. edit the quota. Let's use the setquota tool, that could be used later in some ansible playbook someday, unlike edquota which runs an interactive editor:

setquota -P testproj 0 1234 0 0 /mnt/loop/

8. confirm the quota is set

repquota  -P   /mnt/loop/
# in some parsable format, assuming you wrote some simple enough strings in projid, since the xml formatter is pretty basic
repquota -P /mnt/loop/ -O xml

9. verify it works:

as a normal user:

dd if=/dev/zero of=someoutput oflag=append
loop0: write failed, project block limit reached.
dd: writing to 'someoutput': Disk quota exceeded
2471+0 records in
2470+0 records out
1264640 bytes (1.3 MB, 1.2 MiB) copied, 0.00985608 s, 128 MB/s

10. verify you can trivially escape it though, as a normal user:

chattr  -p 43 someoutput
dd if=/dev/zero of=someoutput oflag=append
dd: writing to 'someoutput': No space left on device
127427+0 records in
127426+0 records out
65242112 bytes (65 MB, 62 MiB) copied, 0.561987 s, 116 MB/s

here completely filling the file system.

EDIT: more info on the limitations of project quotas Re: Project Quota file owner could change its project ID?, Re: ext4 and project quotas bugs (/ features)

Here's a working example with the python code you cited:

Usage: tree.py -f [file limit] <directory>

If a number is specified for -f [file limit] then ... <additional files> is printed and the other files are skipped. Additional directories should not be skipped however. If the file limit is set to 10000 (default) this acts as no limit

#! /usr/bin/env python
# tree.py
#
# Written by Doug Dahms
# modified by glallen @ StackExchange
#
# Prints the tree structure for the path specified on the command line

from os import listdir, sep
from os.path import abspath, basename, isdir
from sys import argv

def tree(dir, padding, print_files=False, limit=10000):
    print padding[:-1] + '+-' + basename(abspath(dir)) + '/'
    padding = padding + ' '
    limit = int(limit)
    files = []
    if print_files:
        files = listdir(dir)
    else:
        files = [x for x in listdir(dir) if isdir(dir + sep + x)]
    count = 0
    for file in files:
        count += 1
        path = dir + sep + file
        if isdir(path):
            print padding + '|'
            if count == len(files):
                tree(path, padding + ' ', print_files, limit)
            else:
                tree(path, padding + '|', print_files, limit)
        else:
            if limit == 10000:
                print padding + '|'
                print padding + '+-' + file
                continue
            elif limit == 0:
                print padding + '|'
                print padding + '+-' + '... <additional files>'
                limit -= 1
            elif limit <= 0:
                continue
            else:
                print padding + '|'
                print padding + '+-' + file
                limit -= 1

def usage():
    return '''Usage: %s [-f] [file-listing-limit(int)] <PATH>
Print tree structure of path specified.
Options:
-f          Print files as well as directories
-f [limit]  Print files as well as directories up to number limit
PATH        Path to process''' % basename(argv[0])

def main():
    if len(argv) == 1:
        print usage()
    elif len(argv) == 2:
        # print just directories
        path = argv[1]
        if isdir(path):
            tree(path, ' ')
        else:
            print 'ERROR: \'' + path + '\' is not a directory'
    elif len(argv) == 3 and argv[1] == '-f':
        # print directories and files
        path = argv[2]
        if isdir(path):
            tree(path, ' ', True)
        else:
            print 'ERROR: \'' + path + '\' is not a directory'
    elif len(argv) == 4 and argv[1] == '-f':
        # print directories and files up to max
        path = argv[3]
        if isdir(path):
            tree(path, ' ', True, argv[2])
        else:
            print 'ERROR: \'' + path + '\' is not a directory'
    else:
        print usage()

if __name__ == '__main__':
    main()

When run, it should produce output similar to:

user@host /usr/share/doc $ python /tmp/recipe-217212-1.py -f 2 . | head -n 40
+-doc/
  |
  +-libgnuradio-fft3.7.2.1/
  | |
  | +-copyright
  | |
  | +-changelog.Debian.gz
  |
  +-libqt4-script/
  | |
  | +-LGPL_EXCEPTION.txt
  | |
  | +-copyright
  | |
  | +-... <additional files>
  |
  +-xscreensaver-gl/
  | |
  | +-copyright
  | |
  | +-changelog.Debian.gz
  | |
  | +-... <additional files>