Fixes for error propagation

Author: hudlow

features/error_propagation.feature

@@ -0,0 +1,122 @@
+Feature: error_propagation
+         Tests to ensure errors propagate how they are supposed to
+
+Scenario: equal
+
+    When CEL expression '{}.a == 1' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: not_equal
+
+    When CEL expression '{}.a != 1' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: greater_than
+
+    When CEL expression '{}.a > 1' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: greater_than_or_equal
+
+    When CEL expression '{}.a >= 1' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: less_than
+
+    When CEL expression '{}.a > 1' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: less_than_or_equal
+
+    When CEL expression '{}.a >= 1' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: add
+
+    When CEL expression '{}.a + 1' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: subtract
+
+    When CEL expression '{}.a - 1' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: multiply
+
+    When CEL expression '{}.a * 1' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: divide
+
+    When CEL expression '{}.a / 1' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: modulo
+
+    When CEL expression '{}.a % 1' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: in
+
+    When CEL expression '{}.a in [1]' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: function
+
+    When CEL expression 'size({}.a)' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: method
+
+    When CEL expression '{}.a.size()' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: not
+
+    When CEL expression '!{}.a' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: and_error
+
+    When CEL expression '{}.a && true' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: and_ignore
+
+    When CEL expression '{}.a && false' is evaluated
+    Then eval_error is None
+
+Scenario: or_error
+
+    When CEL expression '{}.a || false' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: or_ignore
+
+    When CEL expression '{}.a || true' is evaluated
+    Then eval_error is None
+
+Scenario: all_error
+
+    When CEL expression '[{"a": 1}, {}].all(v, v.a == 1)' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: all_ignore
+
+    When CEL expression '[{"a": 1}, {}].all(v, v.a == 2)' is evaluated
+    Then eval_error is None
+
+Scenario: exists_error
+
+    When CEL expression '[{"a": 1}, {}].exists(v, v.a == 2)' is evaluated
+    Then eval_error is "no such member"
+
+Scenario: exists_ignore
+
+    When CEL expression '[{"a": 1}, {}].exists(v, v.a == 1)' is evaluated
+    Then eval_error is None
+
+Scenario: exists_one_error
+
+    When CEL expression '[{"a": 1}, {}].exists_one(v, v.a == 1)' is evaluated
+    Then eval_error is "no such member"

src/celpy/celtypes.py

@@ -334,6 +334,8 @@ def logical_not(x: Value) -> Value:
     This could almost be `logical_or = evaluation.boolean(operator.not_)`,
     but the definition would expose Python's notion of "truthiness", which isn't appropriate for CEL.
     """
+    if isinstance(x, Exception):
+        return x
     if isinstance(x, BoolType):
         result_value = BoolType(not x)
     else:

src/celpy/evaluation.py

@@ -291,6 +291,11 @@ def boolean(
     def bool_function(
         a: celpy.celtypes.Value, b: celpy.celtypes.Value
     ) -> celpy.celtypes.BoolType:
+        if isinstance(a, CELEvalError):
+            return a
+        if isinstance(b, CELEvalError):
+            return b
+
         result_value = function(a, b)
         if result_value == NotImplemented:
             return cast(celpy.celtypes.BoolType, result_value)
@@ -323,7 +328,9 @@ def operator_in(item: Result, container: Result) -> Result:
 
     -   True. There was a item found. Exceptions may or may not have been found.
     -   False. No item found AND no exceptions.
-    -   CELEvalError. No item found AND at least one exception.
+    -   CELEvalError. Either:
+        - No item found AND at least one exception or
+        - The input item or container itself was already an error
 
     To an extent this is a little like the ``exists()`` macro.
     We can think of ``container.contains(item)`` as ``container.exists(r, r == item)``.
@@ -333,6 +340,11 @@ def operator_in(item: Result, container: Result) -> Result:
 
         ``reduce(logical_or, (item == c for c in container), BoolType(False))``
     """
+    if isinstance(item, CELEvalError):
+        return item
+    if isinstance(container, CELEvalError):
+        return container
+
     result_value: Result = celpy.celtypes.BoolType(False)
     for c in cast(Iterable[Result], container):
         try:
@@ -1547,6 +1559,9 @@ def function_eval(
 
         try:
             list_exprlist = cast(List[Result], exprlist or [])
+            for expr in list_exprlist:
+                if isinstance(expr, CELEvalError):
+                    return expr
             return function(*list_exprlist)
         except ValueError as ex:
             value = CELEvalError(