The previous commit fixed the FrameIO/LDF diagram by labeling the
ldf-lookup edge as "duck-typed" without defining the term. This commit
adds a dedicated section explaining what duck typing means in this
codebase, why both architectural seams (FrameIO's ldf injection and the
lin fixture's adapter swap) rely on it, and the Python idioms behind it.
Content covers:
- The "walks like a duck" slogan and what it means in code: shape of
used methods is the contract, not the class.
- Example 1 — FrameIO and the untyped `ldf` parameter: shows the
contract (single .frame() call) and the absence of any
`from ecu_framework.lin.ldf import LdfDatabase`. Includes the
counter-example of what nominal typing would have meant for
module dependencies and testability.
- Example 2 — the lin fixture and adapter polymorphism: same idiom,
with LinInterface providing the nominal anchor.
- EAFP ("Easier to Ask Forgiveness than Permission") as the supporting
Python idiom, contrasted with LBYL.
- The trade-off section: implicit contracts and runtime-only errors,
and how the codebase mitigates them.
Cross-linked from 24_test_wiring.md's `lin` polymorphism-boundary
discussion so readers of either doc can navigate to the explanation.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Restructures tests/hardware/ so that fixture access is controlled by
directory layout — pytest only walks upward through conftest.py files,
so a PSU test physically cannot request fio/alm/nad.
Layout:
- tests/hardware/conftest.py (unchanged: PSU fixtures)
- tests/hardware/mum/conftest.py NEW: _require_mum (session autouse),
fio (session), nad (session),
alm (session), _reset_to_off
(function autouse)
- tests/hardware/mum/** MUM tests + swe5/ + swe6/
- tests/hardware/psu/** PSU-only tests
- tests/hardware/babylin/** deprecated BabyLIN E2E
What this removes (was duplicated before):
- 7 verbatim copies of the `fio` fixture
- 6 copies of the `alm` fixture
- 6 copies of the `_reset_to_off` autouse
- 9 inline `if config.interface.type != "mum": pytest.skip(...)` gates
What this changes by design:
- fio / alm / nad scope: module → session. NAD discovery happens once
per run instead of once per module. The helpers are immutable beyond
their constructor args, so sharing them is safe; per-test state is
reset by the autouse `_reset_to_off`.
- test_overvolt.py: `_park_at_nominal` is now `_reset_to_off`, which
cleanly overrides the conftest's LED-only version (PSU + LED reset).
- test_mum_alm_animation_generated.py keeps a local `_reset_to_off` +
`_force_off` so its "no AlmTester anywhere" demonstration is preserved
via fixture override; the local `nad` is also retained because it
uses the typed `AlmStatus.receive` API.
Docs:
- docs/24_test_wiring.md NEW — describes the three-layer fixture
topology, lifecycle sequence diagram, helper class wiring, and the
playbook for adding a new framework component.
- docs/05_architecture_overview.md: add MCF (mum conftest) node to the
Mermaid diagram + mention it in the components list.
- docs/19_frame_io_and_alm_helpers.md: replace the per-module
fixture-wiring example with a request-fixtures-by-name snippet plus
the override pattern.
- Path references swept across docs/02, docs/14, docs/18, docs/20,
docs/README to point at the new locations.
Verified: pytest --collect-only collects 93 tests with no errors;
30 unit tests and 10 mock-only smoke tests pass; fixture-per-test
output shows PSU tests cannot see fio/alm/nad.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
