Test:
```
def test_params(self, atf_vars):
print(os.environ)
print(atf_vars)
print(atf_vars.get("fibs"))
```
Execution (test suit vm):
```
kyua debug -k /usr/tests/sys/net/routing/Kyuafile test_rtsock_multipath.py:TestRtmMultipath::test_params
epair0a: Ethernet address: 02:4a:42:75:48:0a
epair0b: Ethernet address: 02:4a:42:75:48:0b
epair0a: link state changed to UP
epair0b: link state changed to UP
epair0a: link state changed to DOWN
epair0b: link state changed to DOWN
============================= test session starts ==============================
platform freebsd14 -- Python 3.8.13, pytest-7.1.2, pluggy-1.0.0
rootdir: /usr/tests/sys/net/routing
collected 1 item
../../../../usr/tests/sys/net/routing/test_rtsock_multipath.py
environ({'LC_CTYPE': 'C.UTF-8', '_ATF_VAR_unprivileged-user': 'tests', '_ATF_VAR_fibs': '1 2', '_ATF_VAR_disks': '/dev/vtbd2 /dev/vtbd3 /dev/vtbd4 /dev/vtbd5 /dev/vtbd6', '_ATF_VAR_ci': 'true', '_ATF_VAR_cam_test_device': '/dev/ada0', '_ATF_VAR_allow_sysctl_side_effects': '1', 'PYTHONPATH': '/usr/tests', '__RUNNING_INSIDE_ATF_RUN': 'internal-yes-value', 'TZ': 'UTC', 'TMPDIR': '/tmp/kyua.HOX4TI/2/work', 'HOME': '/tmp/kyua.HOX4TI/2/work', 'LOGNAME': 'root', 'PAGER': 'less', 'MAIL': '/var/mail/root', 'PATH': '/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin:/root/bin', 'ENV': '/root/.shrc', 'PWD': '/root', 'TERM': 'vt100', 'USER': 'root', 'SHELL': '/bin/sh', 'MM_CHARSET': 'UTF-8', 'BLOCKSIZE': 'K', 'PYTEST_CURRENT_TEST': 'test_rtsock_multipath.py::TestRtmMultipath::test_params (setup)'})
run: '/sbin/ifconfig epair create'
run: '/usr/sbin/jail -i -c name=jail_test_params persist vnet vnet.interface=epair0a'
run: 'jexec jail_test_params /sbin/ifconfig -l'
{'unprivileged-user': 'tests', 'fibs': '1 2', 'disks': '/dev/vtbd2 /dev/vtbd3 /dev/vtbd4 /dev/vtbd5 /dev/vtbd6', 'ci': 'true', 'cam_test_device': '/dev/ada0', 'allow_sysctl_side_effects': '1'}
1 2
.
============================== 1 passed in 1.09s ===============================
```