mux: Improve the variant_id

Use the combination of path-ordered leaves names and a hash of combined
fingerprint as variant_id. This should improve human-readability of the
results and also it should produce machine-friendly unique names, which
change when values in variant are modified.

Because the leaves names are ordered by path, the order of yaml file
does not affect the variant_id. On the other hand any modified/added
value changes the fingerprint and therefor variant_id.

Important feature is also that the variant still contains the
default_params, but the variant-id is not affected by it.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

avocado/core/mux.py

@@ -24,6 +24,7 @@ a custom Varianter plugin.
 import collections
 import itertools
 import re
+import sha
 
 from . import output
 from . import tree
@@ -163,6 +164,16 @@ class MuxPlugin(object):
         self.root = root
         self.mux_path = mux_path
         self.debug = debug
+        self.variant_ids = self._get_variant_ids()
+
+    def _get_variant_ids(self):
+        variant_ids = []
+        for variant in MuxTree(self.root):
+            variant.sort(key=lambda x: x.path)
+            fingerprint = "-".join(_.fingerprint() for _ in variant)
+            variant_ids.append("-".join(node.name for node in variant) + '-' +
+                               sha.sha(fingerprint).hexdigest()[:4])
+        return variant_ids
 
     def __iter__(self):
         """
@@ -170,8 +181,8 @@ class MuxPlugin(object):
         """
         if self.root is None:
             return
-        for i, variant in enumerate(self.variants, 1):
-            yield {"variant_id": i,
+        for vid, variant in itertools.izip(self.variant_ids, self.variants):
+            yield {"variant_id": vid,
                    "variant": variant,
                    "mux_path": self.mux_path}
 

selftests/functional/test_multiplex.py

@@ -15,7 +15,7 @@ basedir = os.path.abspath(basedir)
 AVOCADO = os.environ.get("UNITTEST_AVOCADO_CMD", "./scripts/avocado")
 
 
-DEBUG_OUT = """Variant 16:    amd@examples/mux-environment.yaml, virtio@examples/mux-environment.yaml, mint@examples/mux-environment.yaml, debug@examples/mux-environment.yaml
+DEBUG_OUT = """Variant mint-debug-amd-virtio-5e02:    amd@examples/mux-environment.yaml, virtio@examples/mux-environment.yaml, mint@examples/mux-environment.yaml, debug@examples/mux-environment.yaml
     /distro/mint:init         => systemv@examples/mux-environment.yaml:/distro/mint
     /env/debug:opt_CFLAGS     => -O0 -g@examples/mux-environment.yaml:/env/debug
     /hw/cpu/amd:cpu_CFLAGS    => -march=athlon64@examples/mux-environment.yaml:/hw/cpu/amd

selftests/unit/test_mux.py

@@ -204,6 +204,27 @@ class TestMuxTree(unittest.TestCase):
         self.assertRaises(ValueError,
                           self.tree.get_node, '/non-existing-node')
 
+    def test_fingerprint_order(self):
+        """
+        Checks whether different order changes the fingerprint
+        """
+        children1 = (tree.TreeNode("child1"), tree.TreeNode("child2"))
+        tree1 = tree.TreeNode("root", children=children1)
+        children2 = (tree.TreeNode("child2"), tree.TreeNode("child1"))
+        tree2 = tree.TreeNode("root", children=children2)
+        mux1 = mux.MuxPlugin()
+        mux2 = mux.MuxPlugin()
+        mux1.initialize_mux(tree1, "", False)
+        mux2.initialize_mux(tree2, "", False)
+        mux1.update_defaults(tree.TreeNode())
+        mux2.update_defaults(tree.TreeNode())
+        variant1 = iter(mux1).next()
+        variant2 = iter(mux2).next()
+        self.assertNotEqual(variant1, variant2)
+        self.assertEqual(str(variant1), "{'mux_path': '', 'variant': "
+                         "[TreeNode(name='child1'), TreeNode(name="
+                         "'child2')], 'variant_id': 'child1-child2-9154'}")
+
 
 class TestMultiplex(unittest.TestCase):