Support None value for telemetry values.

tools/telemetry/telemetry/value/list_of_string_values_unittest.py

Index: tools/telemetry/telemetry/value/list_of_string_values_unittest.py
diff --git a/tools/telemetry/telemetry/value/list_of_string_values_unittest.py b/tools/telemetry/telemetry/value/list_of_string_values_unittest.py
index e53022ff8eebf9eaabe398fb837a03b2a0099f82..e4f974e16455754463319e1870618bc69e8d5f2a 100644
--- a/tools/telemetry/telemetry/value/list_of_string_values_unittest.py
+++ b/tools/telemetry/telemetry/value/list_of_string_values_unittest.py
@@ -7,6 +7,7 @@ import unittest
 from telemetry import value
 from telemetry.page import page_set
 from telemetry.value import list_of_string_values
+from telemetry.value import none_values
 
 
 class TestBase(unittest.TestCase):
@@ -61,12 +62,13 @@ class ListOfStringValuesTest(TestBase):
 
   def testListDifferentPageMerging(self):
     page0 = self.pages[0]
+    page1 = self.pages[0]
     v0 = list_of_string_values.ListOfStringValues(
         page0, 'x', 'label',
-        ['L1', 'L2'], same_page_merge_policy=value.PICK_FIRST)
+        ['L1', 'L2'], same_page_merge_policy=value.CONCATENATE)
     v1 = list_of_string_values.ListOfStringValues(
-        page0, 'x', 'label',
-        ['L3', 'L4'], same_page_merge_policy=value.PICK_FIRST)
+        page1, 'x', 'label',
+        ['L3', 'L4'], same_page_merge_policy=value.CONCATENATE)
     self.assertTrue(v1.IsMergableWith(v0))
 
     vM = (list_of_string_values.ListOfStringValues.
@@ -74,10 +76,38 @@ class ListOfStringValuesTest(TestBase):
     self.assertEquals(None, vM.page)
     self.assertEquals('x', vM.name)
     self.assertEquals('label', vM.units)
-    self.assertEquals(value.PICK_FIRST, vM.same_page_merge_policy)
+    self.assertEquals(value.CONCATENATE, vM.same_page_merge_policy)
     self.assertEquals(True, vM.important)
     self.assertEquals(['L1', 'L2', 'L3', 'L4'], vM.values)
 
+  def testListWithNoneValueMerging(self):
+    page0 = self.pages[0]
+    v0 = list_of_string_values.ListOfStringValues(
+        page0, 'x', 'unit',
+        ['L1', 'L2'], same_page_merge_policy=value.CONCATENATE)
+    v1 = list_of_string_values.ListOfStringValues(
+        page0, 'x', 'unit',
+        None, same_page_merge_policy=value.CONCATENATE, none_value_reason='n')
+    self.assertTrue(v1.IsMergableWith(v0))
+
+    vM = (list_of_string_values.ListOfStringValues.
+          MergeLikeValuesFromSamePage([v0, v1]))
+    self.assertEquals(None, vM.values)
+    self.assertEquals(none_values.MERGE_FAILURE_REASON, vM.none_value_reason)
+
+  def testListWithNoneValueMustHaveNoneReason(self):
+    page0 = self.pages[0]
+    self.assertRaises(none_values.NoneValueMissingReason,
+                      lambda: list_of_string_values.ListOfStringValues(
+                          page0, 'x', 'unit', None))
+
+  def testListWithNoneReasonMustHaveNoneValue(self):
+    page0 = self.pages[0]
+    self.assertRaises(none_values.ValueMustHaveNoneValue,
+                      lambda: list_of_string_values.ListOfStringValues(
+                          page0, 'x', 'unit', ['L1', 'L2'],
+                          none_value_reason='n'))
+
   def testAsDict(self):
     v = list_of_string_values.ListOfStringValues(
         None, 'x', 'unit', ['foo', 'bar'],
@@ -88,6 +118,17 @@ class ListOfStringValuesTest(TestBase):
           'values': ['foo', 'bar']
         })
 
+  def testNoneValueAsDict(self):
+    v = list_of_string_values.ListOfStringValues(
+        None, 'x', 'unit', None, same_page_merge_policy=value.PICK_FIRST,
+        important=False, none_value_reason='n')
+    d = v.AsDictWithoutBaseClassEntries()
+
+    self.assertEquals(d, {
+          'values': None,
+          'none_value_reason': 'n'
+        })
+
   def testFromDict(self):
     d = {
       'type': 'list_of_string_values',
@@ -99,3 +140,17 @@ class ListOfStringValuesTest(TestBase):
 
     self.assertTrue(isinstance(v, list_of_string_values.ListOfStringValues))
     self.assertEquals(v.values, ['foo', 'bar'])
+
+  def testFromDictNoneValue(self):
+    d = {
+      'type': 'list_of_string_values',
+      'name': 'x',
+      'units': 'unit',
+      'values': None,
+      'none_value_reason': 'n'
+    }
+    v = value.Value.FromDict(d, {})
+
+    self.assertTrue(isinstance(v, list_of_string_values.ListOfStringValues))
+    self.assertEquals(v.values, None)
+    self.assertEquals(v.none_value_reason, 'n')