[Telemetry] Also merge across tir_labels for TBM

telemetry/telemetry/value/value_unittest.py

Index: telemetry/telemetry/value/value_unittest.py
diff --git a/telemetry/telemetry/value/value_unittest.py b/telemetry/telemetry/value/value_unittest.py
index 9cf9a4c767e307f4189859679fb4fec44981fa5c..a06300edd52fa2441b6d6b3c6b930ff70bf32ec5 100644
--- a/telemetry/telemetry/value/value_unittest.py
+++ b/telemetry/telemetry/value/value_unittest.py
@@ -322,3 +322,16 @@ class ValueTest(TestBase):
     vs = value.Value.ListOfValuesFromListOfDicts([d0, d1], {})
     self.assertEquals(vs[0].name, 'x')
     self.assertEquals(vs[1].name, 'y')
+
+  def testMergedTirLabelForSameLabel(self):
+    v = ValueForTest(None, 'foo', 'ms', False, 'd', 'bar', {})
+
+    tir_label = value.MergedTirLabel([v, v])
+    self.assertEquals(tir_label, 'bar')
+
+  def testMergedTirLabelForDifferentLabels(self):
+    v0 = ValueForTest(None, 'foo', 'ms', False, 'd', 'bar', {})
+    v1 = ValueForTest(None, 'foo', 'ms', False, 'd', 'baz', {})
+
+    tir_label = value.MergedTirLabel([v0, v1])
+    self.assertIsNone(tir_label)