Add JunOS pre-transfer free-space check (NAPPS-1085)

[jtdub]

Summary

• Implements the fail-open pre-transfer free-space check on Juniper Junos using the seam added in NAPPS-1091 (PR Add EOS pre-transfer free-space check (NAPPS-1091) #370), so image transfers fail fast when the target mount point (default /var/tmp) lacks room instead of half-writing flash.
• JunosDevice._get_free_space uses PyEZ's FS.storage_usage() and parses the human-readable avail format (e.g., "126M", "1.0G"). PyEZ does not expose a native block size and Junos block semantics vary by release, so parsing the normalised human-readable field avoids the ambiguity. Defaults to /var/tmp and raises FileSystemNotFoundError when the mount is absent.
• file_copy calls _check_free_space(os.path.getsize(src)) before SCP put; remote_file_copy gains an optional file_system kwarg and calls _pre_transfer_space_check before fs.cp so the check fires only when an actual transfer would happen.
• Unit tests cover the avail parse across K/M/G units, the mount-not-found raise, the unparseable-avail raise, file_copy raising before SCP put, remote_file_copy raising before fs.cp, and the fail-open path. Integration tests mirror the EOS / ASA patterns for manual lab runs. TFTP is excluded because PyEZ fs.cp does not accept TFTP URLs.

NAPPS-1085

Test plan

• poetry run pytest tests/unit/test_devices/test_jnpr_device.py — all 45 pass (7 new).
• poetry run pytest tests/unit — all 661 pass.
• poetry run ruff check pyntc tests — clean.
• Lab run: poetry run pytest tests/integration/test_jnpr_device.py -v with JUNOS_HOST / JUNOS_USER / JUNOS_PASS + protocol URLs + FILE_CHECKSUM / FILE_SIZE / FILE_SIZE_UNIT set — verifies the probe, the oversized reject, and the fail-open path end-to-end.

🤖 Generated with Claude Code

[jtdub]

% source .env && poetry run pytest tests/integration/test_jnpr_device.py -v
========================================================= test session starts =========================================================
platform darwin -- Python 3.12.11, pytest-9.0.3, pluggy-1.6.0 -- /Users/jameswilliams/Library/Caches/pypoetry/virtualenvs/pyntc-gs002iVE-py3.12/bin/python
cachedir: .pytest_cache
rootdir: /Users/jameswilliams/Documents/code/pyntc
configfile: pyproject.toml
plugins: f5-sdk-3.0.21, requests-mock-1.12.1
collected 14 items                                                                                                                    

tests/integration/test_jnpr_device.py::test_device_connects PASSED                                                              [  7%]
tests/integration/test_jnpr_device.py::test_check_file_exists_false PASSED                                                      [ 14%]
tests/integration/test_jnpr_device.py::test_remote_file_copy_ftp PASSED                                                         [ 21%]
tests/integration/test_jnpr_device.py::test_remote_file_copy_scp PASSED                                                         [ 28%]
tests/integration/test_jnpr_device.py::test_remote_file_copy_http PASSED                                                        [ 35%]
tests/integration/test_jnpr_device.py::test_remote_file_copy_https PASSED                                                       [ 42%]
tests/integration/test_jnpr_device.py::test_verify_file_after_copy PASSED                                                       [ 50%]
tests/integration/test_jnpr_device.py::test_get_free_space_returns_positive_int PASSED                                          [ 57%]
tests/integration/test_jnpr_device.py::test_check_free_space_succeeds_for_small_request PASSED                                  [ 64%]
tests/integration/test_jnpr_device.py::test_check_free_space_raises_when_required_exceeds_free PASSED                           [ 71%]
tests/integration/test_jnpr_device.py::test_file_size_unit_conversion_matches_device_free_space PASSED                          [ 78%]
tests/integration/test_jnpr_device.py::test_remote_file_copy_rejects_oversized_transfer PASSED                                  [ 85%]
tests/integration/test_jnpr_device.py::test_remote_file_copy_accepts_declared_size_within_free_space PASSED                     [ 92%]
tests/integration/test_jnpr_device.py::test_remote_file_copy_skips_space_check_when_file_size_omitted PASSED                    [100%]

========================================================= 14 passed in 19.65s =========================================================

[mattmiller87]

I think I would want to add a JUNOS_SUPPORTED_HASHING_ALGORITHMS so that we can make any integration or testing simpler.

[mattmiller87]

Junos looks good to me.