undefined state variables now throw a NameError exception, instead of returning None

Author: craigbarratt

custom_components/pyscript/state.py

@@ -124,12 +124,14 @@ def get(cls, var_name):
         """Get a state variable value or attribute from hass."""
         parts = var_name.split(".")
         if len(parts) != 2 and len(parts) != 3:
-            raise NameError(f"invalid name {var_name} (should be 'domain.entity')")
+            raise NameError(f"invalid name '{var_name}' (should be 'domain.entity')")
         value = cls.hass.states.get(f"{parts[0]}.{parts[1]}")
         if not value:
-            return None
+            raise NameError(f"name '{parts[0]}.{parts[1]}' is not defined")
         if len(parts) == 2:
             return value.state
+        if parts[2] not in value.attributes:
+            raise AttributeError(f"state '{parts[0]}.{parts[1]}' has no attribute '{parts[2]}'")
         return value.attributes.get(parts[2])
 
     @classmethod

docs/reference.rst

@@ -69,10 +69,8 @@ Also, service names (which are called as functions) take priority over state var
 component has a state variable name that collides with one of its services, you’ll need to use
 ``state.get(name)`` to access that state variable.
 
-Finally, state variables that don’t exist evaluate to ``None``, rather than throwing an exception.
-That makes it easy to test if a state variable has a valid value.  In contrast, accessing a state
-attribute using ``DOMAIN.name.attr`` will throw an exception if the attribute doesn't exist
-(``None`` could be a valid attribute value).
+Accessing state variables don't exist will throw a ``NameError`` exception, and accessing an
+attribute that doesn't exist will throw a ``AttributeError`` exception.
 
 Calling services
 ----------------
@@ -473,10 +471,10 @@ variable using its string name. The set function also allows you to optionally s
 which you can’t do if you are directly assigning to the variable:
 
 ``state.get(name)``
-  Returns the value of the state variable given its string ``name``, or ``None`` if it doesn’t exist.
-  If ``name`` is a string of the form ``DOMAIN.entity.attr`` then the attribute ``attr`` of the
-  state variable ``DOMAIN.entity`` is returned; an exception is thrown if that attribute doesn't
-  exist.
+  Returns the value of the state variable given its string ``name``. A ``NameError`` exception
+  is thrown if the name doesn't exist.  If ``name`` is a string of the form ``DOMAIN.entity.attr``
+  then the attribute ``attr`` of the state variable ``DOMAIN.entity`` is returned; an
+  ``AttributeError`` exception is thrown if that attribute doesn't exist.
 ``state.get_attr(name)``
   Returns a ``dict`` of attribute values for the state variable, or ``None``
   if it doesn’t exist

tests/test_unique.py

@@ -199,6 +199,7 @@ def func6():
     #
     # now run func4() a few times; each one should stop the last one
     #
+    hass.states.async_set("pyscript.f4var2", 0)
     for _ in range(10):
         seq_num += 1
         hass.states.async_set("pyscript.f4var1", 0)
@@ -222,6 +223,7 @@ def func6():
     # start and the rest will not
     #
     seq_num += 1
+    hass.states.async_set("pyscript.f5var2", 0)
     hass.states.async_set("pyscript.f5var1", 0)
     hass.states.async_set("pyscript.f5var1", 1)
     assert literal_eval(await wait_until_done(notify_q)) == [

tests/test_unit_eval.py

@@ -896,7 +896,7 @@ async def test_eval(hass):
     ["task.executor(5)", "Exception in test line 1 column 14: function is not callable by task.executor()"],
     [
         "import cmath; exec('xyz = cmath.sqrt(complex(3, 4))', {})",
-        "Exception in test line 1 column 54: Exception in exec() line 1 column 28: 'sqrt' is not callable (got None)",
+        "Exception in test line 1 column 54: Exception in exec() line 1 column 6: name 'cmath.sqrt' is not defined",
     ],
     ["func1(1)", "Exception in test line 1 column 0: name 'func1' is not defined"],
     [