[Nexthop][fboss2-dev] Add some end-to-end tests for the CLI

[benoit-nexthop]

Pre-submission checklist

• I've ran the linters locally and fixed lint errors related to the files I modified in this PR. You can install the linters by running pip install -r requirements-dev.txt && pre-commit install
• pre-commit run

Summary

Add end-to-end tests to be run on an FBOSS DUT to validate CLI commands.

Note: this change is part of a series, the previous one is #761, the next one is #789.

Test Plan

New end-to-end test coverage for fboss2-dev config interface <name> mtu <N> and fboss2-dev config interface <name> description <string>

Sample output of run_test.py cli:

Setting fboss environment variables
Running CLI end-to-end tests...

########## Running CLI test: test_config_interface_description.py
[  PASSED  ] test_config_interface_description.py (84.0s)

########## Running CLI test: test_config_interface_mtu.py
[  PASSED  ] test_config_interface_mtu.py (71.8s)

============================================================
CLI Test Summary
============================================================
  Passed: 2
  Failed: 0
  Total:  2
  Time:   155.8s

Detailed output of each test suite:

============================================================
CLI E2E Test: config interface <name> description <string>
============================================================

[Step 1] Finding an interface to test...
  Using CLI from FBOSS_CLI_PATH: /home/admin/benoit/fboss2-dev
[CLI] Running: show interface
[CLI] Completed in 18.14s: show interface
  Using interface: eth1/1/1 (VLAN: 2001)

[Step 2] Getting current description...
[CLI] Running: show interface eth1/1/1
[CLI] Completed in 17.78s: show interface eth1/1/1
  Current description: 'Test revision 2'

[Step 3] Setting description to 'CLI_E2E_TEST_DESCRIPTION'...
[CLI] Running: config interface eth1/1/1 description CLI_E2E_TEST_DESCRIPTION
[CLI] Completed in 0.06s: config interface eth1/1/1 description CLI_E2E_TEST_DESCRIPTION
[CLI] Running: config session commit
[CLI] Completed in 7.43s: config session commit
  Description set to 'CLI_E2E_TEST_DESCRIPTION'

[Step 4] Verifying description via 'show interface'...
[CLI] Running: show interface eth1/1/1
[CLI] Completed in 21.38s: show interface eth1/1/1
  Verified: Description is 'CLI_E2E_TEST_DESCRIPTION'

[Step 5] Restoring original description ('Test revision 2')...
[CLI] Running: config interface eth1/1/1 description Test revision 2
[CLI] Completed in 0.05s: config interface eth1/1/1 description Test revision 2
[CLI] Running: config session commit
[CLI] Completed in 6.34s: config session commit
  Restored description to 'Test revision 2'
[CLI] Running: show interface eth1/1/1
[CLI] Completed in 19.31s: show interface eth1/1/1

============================================================
TEST PASSED
============================================================

============================================================
CLI E2E Test: config interface <name> mtu <N>
============================================================

[Step 1] Finding an interface to test...
  Using CLI from FBOSS_CLI_PATH: /home/admin/benoit/fboss2-dev
[CLI] Running: show interface
[CLI] Completed in 21.35s: show interface
  Using interface: eth1/1/1 (VLAN: 2001)

[Step 2] Getting current MTU...
[CLI] Running: show interface eth1/1/1
[CLI] Completed in 19.47s: show interface eth1/1/1
  Current MTU: 9000

[Step 3] Setting MTU to 1500...
[CLI] Running: config interface eth1/1/1 mtu 1500
[CLI] Completed in 0.06s: config interface eth1/1/1 mtu 1500
[CLI] Running: config session commit
[CLI] Completed in 6.52s: config session commit
  MTU set to 1500

[Step 4] Verifying MTU via 'show interface'...
[CLI] Running: show interface eth1/1/1
[CLI] Completed in 19.33s: show interface eth1/1/1
  Verified: MTU is 1500

[Step 5] Verifying kernel interface MTU...
Running: ip link show fboss2001
  Verified: Kernel interface fboss2001 has MTU 1500

[Step 6] Restoring original MTU (9000)...
[CLI] Running: config interface eth1/1/1 mtu 9000
[CLI] Completed in 0.05s: config interface eth1/1/1 mtu 9000
[CLI] Running: config session commit
[CLI] Completed in 5.60s: config session commit
  Restored MTU to 9000

============================================================
TEST PASSED
============================================================