test: refuse drivers that emit numbers they never read

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+## Tests: no invented numbers
+
+- `drivers/tests/lua_harness/no_invented_numbers.lua` runs a driver twice with different registers, config and clock, then makes every read fail and every Modbus reply short. A number the driver still emits that is equal in both runs and was not read is invented: 0 W, 0 A, 0 % SoC, 50 Hz. A failed read must leave the value nil, so the host sends null. Sourceful's driver registry runs the same file on every publish.
+- `drivers/tests/test_no_invented_numbers.py` ratchets against `invented-number-baseline.json`: 44 of 91 drivers carry this debt today. A count that rises fails, a driver not listed must be clean, and a count that falls fails until the file is updated. `make invented-number-report ID=<id>` prints the fields for one driver.
+
 ## tesla_vehicle 0.2.5
 
 - Recover missing, partial and old SoC with a telemetry-only wake and read.

Makefile

@@ -5,7 +5,7 @@ KIND ?= meter
 LEVEL ?= patch
 
 .PHONY: bootstrap new-driver test-driver check boundary \
-	refused-write-report absent-register-report \
+	refused-write-report absent-register-report invented-number-report \
 	sync-manifests bump-driver history ftw-baseline ftw-baseline-report \
 	host-api site watch-upstream-docs
 
@@ -40,6 +40,12 @@ refused-write-report:
 	test -n "$(ID)"
 	./lua55 drivers/tests/lua_harness/refused_write_probe.lua . "drivers/lua/$(ID).lua"
 
+# Which fields a driver still fills with a number once its device stops
+# answering. A failed read has to stay nil, so the host sends null, not 0.
+invented-number-report:
+	test -n "$(ID)"
+	./lua55 drivers/tests/lua_harness/no_invented_numbers.lua drivers/tests/lua_harness "drivers/lua/$(ID).lua"
+
 bootstrap:
 	uv sync --frozen --extra package --extra dev
 

drivers/tests/invented-number-baseline.json

@@ -0,0 +1,59 @@
+{
+  "_comment": [
+    "Fields a driver emits a number for after its device stopped answering,",
+    "a number that came from no read, config or clock (0 W, 50 Hz, 0 % SoC).",
+    "",
+    "This file records debt that already shipped: 44 of the 91 drivers when",
+    "drivers/tests/test_no_invented_numbers.py was added. The test ratchets:",
+    "a count that rises fails, a driver not listed must be clean, and a count",
+    "that falls fails until this file is updated. Shrink it. Never grow it.",
+    "",
+    "make invented-number-report ID=<id> prints the fields for one driver."
+  ],
+  "drivers": {
+    "abb_meter": 13,
+    "abb_terra": 8,
+    "acrel": 13,
+    "acuvim": 8,
+    "alfen": 8,
+    "alphaess": 10,
+    "atmoce": 13,
+    "carlo_gavazzi": 13,
+    "chint": 13,
+    "circutor": 13,
+    "ctek": 9,
+    "ctek_hybrid": 9,
+    "ctek_v2": 9,
+    "deye": 28,
+    "easee": 4,
+    "etrel": 8,
+    "ferroamp_modbus": 18,
+    "fronius": 11,
+    "goe": 8,
+    "goodwe": 24,
+    "growatt": 20,
+    "hello": 3,
+    "janitza": 13,
+    "keba": 8,
+    "kostal": 22,
+    "kstar": 9,
+    "mennekes": 8,
+    "schneider_meter": 13,
+    "schrack_ev": 8,
+    "siemens_pac": 13,
+    "sigenergy": 5,
+    "sma": 28,
+    "sma_pv": 21,
+    "socomec": 13,
+    "sofar": 21,
+    "solaredge": 20,
+    "solax": 15,
+    "solinteg": 27,
+    "solis": 27,
+    "solis_string": 21,
+    "sungrow": 20,
+    "varta": 5,
+    "victron": 10,
+    "wallbox": 2
+  }
+}