PyDABs: acceptance-test authoring skill + per-resource coverage guard - #6527

Stop hand-writing a TestCase per resource in test_resources.py. A new
codegen step (generated_test_cases.py, rendered from test_case.py.tmpl)
synthesizes dict_example and dataclass_example for every wired resource
from the schema model and writes one file per resource under
databricks_tests/core/_generated/, collected into test_cases. A newly
wired resource now gets its unit-test coverage for free.

dict_example and dataclass_example are rendered two independent ways from
one synthesized value tree, so the dict->dataclass _transform assertion
stays meaningful. Field policy: required fields fully expanded, plus
optional composite fields on the resource itself; nested objects
contribute only their required fields, which bounds example size and
avoids the recursive Task/ForEachTask schema. Optional scalar,
deprecated, and private-preview fields are omitted.

The hand-written TestCase dataclass moves to _resource_test_case.py so
the generated modules can import it without a cycle.

Co-authored-by: Isaac <no-reply@databricks.com>

The generator source lives outside databricks/databricks_tests, so
pydabs-codegen's targeted ruff --fix does not reach it, but the root
ruff check does. Sort imports and merge the two startswith calls into a
single tuple call. No change to generated output.

Co-authored-by: Isaac <no-reply@databricks.com>

Skip optional top-level fields ranked below public preview (public-beta and
private-preview), not just private-preview. Mirror the launch-stage rank from
internal/clijson/launchstage.go (absent stage = GA) so the comparison uses
maturity order rather than a string comparison. Drops jobs.triggers and
pipelines.parameters from the generated examples.

Co-authored-by: Isaac <no-reply@databricks.com>

An AI Agent Skill that guides an agent to author the acceptance test for a
newly-onboarded PyDABs resource: the acceptance/bundle/python/<plural>-support/
fixture (databricks.yml + resources.py + mutators.py + script + test.toml +
generated output.txt). Includes fill-in templates (.tmpl so they stay out of
linters). Complements the schema-synthesized unit-test generation; realistic
field values are adapted from the resource's invariant config.

Co-authored-by: Isaac <no-reply@databricks.com>

test_python_support_coverage fails until each resource in the _ResourceType
registry has an acceptance/bundle/python/<plural>-support/ fixture, so coverage
cannot silently regress as resources are onboarded. Mirrors the invariant-config
coverage guard; shrink-only _LACKING allowlist ({jobs}, whose coverage predates
the convention). Lives in the python test suite (runs in CI via pydabs-test) since
it checks the filesystem rather than exercising the CLI.

Co-authored-by: Isaac <no-reply@databricks.com>

Per review feedback (skills aren't reliably loaded, and the examples plus a
verbose failure are enough): drop the pydabs-acceptance-test skill in favor of
the repo's dresources pattern — a path-scoped .agents/rules/ file (auto-loaded
when working under acceptance/bundle/python/**) pointing to a concise
acceptance/bundle/python/README.md that leans on the existing fixtures. Retarget
the coverage guard's message at the README.

Co-authored-by: Isaac <no-reply@databricks.com>

Add tools/validate_cursor_rules.py (wired into `task checks`) so a rule under
.agents/rules/ without its .cursor/rules/<name>.mdc symlink fails CI; `--fix`
auto-creates missing symlinks and drops stale ones. Also add the symlink for the
new pydabs-acceptance-tests rule.

Co-authored-by: Isaac <no-reply@databricks.com>

Remove tools/validate_cursor_rules.py and its check-cursor-rules task; the
symlink-mirror check is being shipped on its own. Keep the
.cursor/rules/pydabs-acceptance-tests.mdc symlink for the rule added here.

Co-authored-by: Isaac <no-reply@databricks.com>