Fix "notValue: null" constraints to actually work right.

We were skipping notValue constraints if the value was null, so "notValue: null"
always passed, no matter what the value was.

The fix is to stop doing that skipping.  Also adds a test that this constraint
fails if the value is in fact null.

Author: bzbarsky-apple

.github/workflows/tests.yaml

@@ -247,7 +247,7 @@ jobs:
                      --chip-tool ./out/linux-x64-chip-tool${CHIP_TOOL_VARIANT}-${BUILD_VARIANT}/chip-tool \
                      run \
                      --iterations 1 \
-                     --expected-failures 1 \
+                     --expected-failures 2 \
                      --keep-going \
                      --test-timeout-seconds 120 \
                      --all-clusters-app ./out/linux-x64-all-clusters-${BUILD_VARIANT}/chip-all-clusters-app \
@@ -398,7 +398,7 @@ jobs:
                      --chip-tool ./out/darwin-x64-chip-tool${CHIP_TOOL_VARIANT}-${BUILD_VARIANT}/chip-tool \
                      run \
                      --iterations 1 \
-                     --expected-failures 1 \
+                     --expected-failures 2 \
                      --keep-going \
                      --test-timeout-seconds 120 \
                      --all-clusters-app ./out/darwin-x64-all-clusters-${BUILD_VARIANT}/chip-all-clusters-app \

scripts/py_matter_yamltests/matter_yamltests/constraints.py

@@ -801,14 +801,15 @@ def get_reason(self, value, value_type_name) -> str:
 
 class _ConstraintNotValue(BaseConstraint):
     def __init__(self, context, not_value):
-        super().__init__(context, types=[], is_null_allowed=True)
+        # NOTE: do not use is_null_allowed=True here, because 'notValue: null' needs to work.
+        super().__init__(context, types=[])
         self._not_value = not_value
 
     def check_response(self, value, value_type_name) -> bool:
         return value != self._not_value
 
     def get_reason(self, value, value_type_name) -> str:
-        return f'The response value "{value}" should differs from the constraint.'
+        return f'The response value "{value}" should differ from the constraint.'
 
 
 class _ConstraintAnyOf(BaseConstraint):

scripts/tests/chiptest/__init__.py

@@ -277,6 +277,7 @@ def _GetPurposefulFailureTests() -> Set[str]:
     """Tests that fail in YAML on purpose."""
     return {
         "TestPurposefulFailureEqualities.yaml"
+        "TestPurposefulFailureNotNullConstraint.yaml"
     }
 
 

src/app/tests/suites/TestPurposefulFailureNotNullConstraint.yaml

@@ -0,0 +1,37 @@
+# Copyright (c) 2024 Project CHIP Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name:
+    Test that notValue constraint that says value must not be null fails if the
+    value is null.
+
+config:
+    nodeId: 0x12344321
+    cluster: "Unit Testing"
+    endpoint: 1
+
+tests:
+    - label: "Write attribute NULLABLE_INT8U null value"
+      command: "writeAttribute"
+      attribute: "nullable_int8u"
+      arguments:
+          value: null
+
+    - label: "Read attribute NULLABLE_INT8U null value with constraint"
+      command: "readAttribute"
+      attribute: "nullable_int8u"
+      response:
+          constraints:
+              # This should fail.
+              notValue: null