[tests] add tests on graph invalidation

tests/test_invalidation.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python
+# coding:utf-8
+from meshroom.core.graph import Graph
+from meshroom.core import desc, registerNodeType
+
+
+class SampleNode(desc.Node):
+    """ Sample Node for unit testing """
+    internalFolder = '{cache}/{nodeType}/{uid0}/'
+    input = desc.File(label='Input', description='', value='', uid=[0], isOutput=False)
+    output = desc.File(label='Output', description='', value='{cache}/{nodeType}/{uid0}/', uid=[], isOutput=True)
+    # No impact on UID
+    paramA = desc.StringParam(label='ParamA', description='', value='', uid=[])
+
+
+registerNodeType(SampleNode)
+
+
+def test_output_invalidation():
+    graph = Graph('')
+    n1 = graph.addNewNode('SampleNode', input='/tmp')
+    n2 = graph.addNewNode('SampleNode')
+    n3 = graph.addNewNode('SampleNode')
+
+    graph.addEdges(
+        (n1.output, n2.input),
+        (n1.output, n3.input)
+    )
+
+    # N1.output ----- N2.input
+    #                \
+    #                 N3.input
+
+    # Compare UIDs of similar attributes on different nodes
+    n2inputUid = n2.input.uid()
+    n3inputUid = n3.input.uid()
+    assert n3inputUid == n2inputUid      # => UIDs are equal
+
+    # Change a parameter outside UID
+    n1.paramA.value = 'a'
+    assert n2.input.uid() == n2inputUid  # => same UID as before
+
+    # Change a parameter impacting UID
+    n1.input.value = "/a/path"
+    assert n2.input.uid() != n2inputUid      # => UID has changed
+    assert n2.input.uid() == n3.input.uid()  # => UIDs on both node are still equal
+