sud: fail fast on malformed sud.json documents, one test per fixture

Sud.load() now calls utils/sud_validate.py's validate_sud() before
parsing: requires a non-empty 'steps' list, and for every resolved
step that sets its own 'temperature', a numeric ramp.rate - the one
genuinely unguarded crash site (ramp['rate'], no .get() fallback) hit
in tasks/sud.py, components/sud_forecast.py and demo_sud.py the moment
that step is reached, which for SudForecastEstimator can be as early
as the Load itself. A refused load is now logged with the specific
reason (previously silent). validate_sud() reuses Sud._parse_data()
directly rather than reimplementing default-merging/step-building.

tests/utils/test_sud_validate_fixtures.py covers 8 fixture docs plus
all 6 real sude/*.json files; tests/components/sud/test_sud_load.py
exercises the Sud.load() wiring itself (rejects, keeps prior schedule).

Also reworked both this and test_config_fixtures.py to generate one
dedicated test method per fixture file (dynamic setattr) instead of
looping with subTest inside a single method - subTest iterations don't
show up individually in `unittest -v`/IDE test runners, which made it
look like far fewer fixtures were covered than actually are.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01F4oEE99rkKVU8L8tkzXWdG

tests/components/sud/test_sud_load.py

@@ -0,0 +1,48 @@
+import json
+import os
+import unittest
+
+from components.sud import Sud
+
+FIXTURES_DIR = os.path.join(os.path.dirname(__file__), '..', '..', 'utils', 'sud_fixtures')
+
+
+def _load_fixture(name):
+    with open(os.path.join(FIXTURES_DIR, name)) as f:
+        return json.load(f)
+
+
+class TestSudLoadRejectsMalformedDocs(unittest.TestCase):
+    """Sud.load() wires in utils/sud_validate.py's validate_sud() so a
+    malformed sud.json is refused (same False-returning contract as any
+    other load() failure - see components/sud.py's own docstring) instead
+    of parsing cleanly and only crashing much later, mid-run or during a
+    forecast simulation, on the unguarded ramp['rate'] lookup."""
+
+    def test_valid_doc_loads(self):
+        sud = Sud()
+        self.assertTrue(sud.load(_load_fixture('valid_multi_step.json')))
+        self.assertEqual(sud.name, 'MultiStep')
+
+    def test_missing_ramp_rate_is_refused(self):
+        sud = Sud()
+        self.assertFalse(sud.load(_load_fixture('missing_ramp_rate.json')))
+
+    def test_wrong_type_ramp_rate_is_refused(self):
+        sud = Sud()
+        self.assertFalse(sud.load(_load_fixture('ramp_rate_wrong_type.json')))
+
+    def test_empty_steps_is_refused(self):
+        sud = Sud()
+        self.assertFalse(sud.load(_load_fixture('empty_steps_list.json')))
+
+    def test_failed_load_leaves_previous_schedule_untouched(self):
+        sud = Sud()
+        self.assertTrue(sud.load(_load_fixture('valid_multi_step.json')))
+        self.assertFalse(sud.load(_load_fixture('missing_ramp_rate.json')))
+        self.assertEqual(sud.name, 'MultiStep')
+        self.assertEqual(len(sud.schedule), 3)
+
+
+if __name__ == '__main__':
+    unittest.main()