[tests] Test attribute callback behavior with dynamic outputs

New test suite that focuses on testing the behavior of the attribute
changes callback system when such an attribute is connected to
an upstream dynamic output value.

tests/test_nodeAttributeChangedCallback.py

@@ -1,6 +1,6 @@
 # coding:utf-8
 
-from meshroom.core.graph import Graph, loadGraph
+from meshroom.core.graph import Graph, loadGraph, executeGraph
 from meshroom.core import desc, registerNodeType, unregisterNodeType
 from meshroom.core.node import Node
 
@@ -309,3 +309,81 @@ class TestAttributeCallbackBehaviorWithUpstreamCompoundAttributes:
         assert nodeB.affectedInput.value == 20
 
 
+class NodeWithDynamicOutputValue(desc.Node):
+    """
+    A Node containing an output attribute which value is computed dynamically during graph execution.
+    """
+
+    inputs = [
+        desc.IntParam(
+            name="input",
+            label="Input",
+            description="Input used in the computation of 'output'",
+            value=0,
+        ),
+    ]
+
+    outputs = [
+        desc.IntParam(
+            name="output",
+            label="Output",
+            description="Dynamically computed output (input * 2)",
+            # Setting value to None makes the attribute dynamic.
+            value=None,
+        ),
+    ]
+
+    def processChunk(self, chunk):
+        chunk.node.output.value = chunk.node.input.value * 2
+
+
+class TestAttributeCallbackBehaviorWithUpstreamDynamicOutputs:
+    @classmethod
+    def setup_class(cls):
+        registerNodeType(NodeWithAttributeChangedCallback)
+        registerNodeType(NodeWithDynamicOutputValue)
+
+    @classmethod
+    def teardown_class(cls):
+        unregisterNodeType(NodeWithAttributeChangedCallback)
+        unregisterNodeType(NodeWithDynamicOutputValue)
+
+    def test_connectingUncomputedDynamicOutputDoesNotTriggerDownstreamAttributeChangedCallback(
+        self,
+    ):
+        graph = Graph("")
+        nodeA = graph.addNewNode(NodeWithDynamicOutputValue.__name__)
+        nodeB = graph.addNewNode(NodeWithAttributeChangedCallback.__name__)
+
+        nodeA.input.value = 10
+        graph.addEdge(nodeA.output, nodeB.input)
+
+        assert nodeB.affectedInput.value == 0
+
+    def test_connectingComputedDynamicOutputTriggersDownstreamAttributeChangedCallback(
+        self, graphWithIsolatedCache
+    ):
+        graph: Graph = graphWithIsolatedCache
+        nodeA = graph.addNewNode(NodeWithDynamicOutputValue.__name__)
+        nodeB = graph.addNewNode(NodeWithAttributeChangedCallback.__name__)
+
+        nodeA.input.value = 10
+        executeGraph(graph)
+
+        graph.addEdge(nodeA.output, nodeB.input)
+        assert nodeA.output.value == nodeB.input.value == 20
+        assert nodeB.affectedInput.value == 40
+
+    def test_dynamicOutputValueComputeDoesNotTriggerDownstreamAttributeChangedCallback(
+        self, graphWithIsolatedCache
+    ):
+        graph: Graph = graphWithIsolatedCache
+        nodeA = graph.addNewNode(NodeWithDynamicOutputValue.__name__)
+        nodeB = graph.addNewNode(NodeWithAttributeChangedCallback.__name__)
+
+        graph.addEdge(nodeA.output, nodeB.input)
+        nodeA.input.value = 10
+        executeGraph(graph)
+
+        assert nodeB.input.value == 20
+        assert nodeB.affectedInput.value == 0