Add test case for mbb severity and fix error

Author: coretl

docs/reference/api.rst

@@ -273,8 +273,8 @@ All functions return a wrapped `ProcessDeviceSupportIn` or
 
         status = mbbIn('STATUS',
             'OK',
-            ('FAILING', alarm.MINOR_ALARM),
-            ('FAILED', alarm.MAJOR_ALARM))
+            ('FAILING', "MINOR"),
+            ('FAILED', "MAJOR"))
 
     Numerical values are assigned to options sequentially from 0 to 15 and
     cannot be overridden.

softioc/builder.py

@@ -72,7 +72,7 @@ def process_value(prefix, value, option, severity=None):
         if severity:
             fields[prefix + 'SV'] = severity
     for prefix, (value, option) in zip(_mbbPrefixes, enumerate(options)):
-        if isinstance(value, tuple):
+        if isinstance(option, tuple):
             # The option is tuple consisting of the option name and an optional
             # alarm severity.
             process_value(prefix, value, *option)

tests/expected_records.db

@@ -631,6 +631,7 @@ record(mbbi, "TS-DI-TEST-01:MBBI")
     field(PINI, "YES")
     field(SCAN, "I/O Intr")
     field(TWST, "Three")
+    field(TWSV, "MINOR")
     field(TWVL, "2")
     field(ZRST, "One")
     field(ZRVL, "0")

tests/sim_records.py

@@ -26,7 +26,7 @@ def on_update_name(value, name):
 t_boolin = boolIn('BOOLIN', 'True', 'False', initial_value=False)
 t_longin = longIn('LONGIN', initial_value=33)
 t_stringin = stringIn('STRINGIN', initial_value="Testing string")
-t_mbbi = mbbIn('MBBI', 'One', 'Two', 'Three', initial_value=2)
+t_mbbi = mbbIn('MBBI', 'One', 'Two', ('Three', "MINOR"), initial_value=2)
 
 t_ao = aOut('AO', initial_value=12.45, on_update_name=on_update_name)
 t_boolout = boolOut(