Implement shortcut for finalizing a trial with all remaining probability

It is helpful when defining experiments to put all remaining probability
on the final (often the "control" group), without having to keep a careful
tally of assignments of probabilities.  This CL implements that functionality.

r=rvargas
Review URL: http://codereview.chromium.org/150141

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@19696 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 20 insertions, 1 deletions

diff --git a/base/field_trial_unittest.cc b/base/field_trial_unittest.cc
index 59d8e15..430fd67 100644
--- a/base/field_trial_unittest.cc
+++ b/base/field_trial_unittest.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -69,6 +69,25 @@ TEST_F(FieldTrialTest, AbsoluteProbabilities) {
   }
 }
 
+TEST_F(FieldTrialTest, RemainingProbability) {
+  // First create a test that hasn't had a winner yet.
+  const std::string winner = "Winner";
+  const std::string loser = "Loser";
+  scoped_refptr<FieldTrial> trial;
+  int counter = 0;
+  do {
+    std::string name = StringPrintf("trial%d", ++counter);
+    trial = new FieldTrial(name, 10);
+    trial->AppendGroup(loser, 5);  // 50% chance of not being chosen.
+  } while (trial->group() != FieldTrial::kNotParticipating);
+
+  // Now add a winner with all remaining probability.
+  trial->AppendGroup(winner, FieldTrial::kAllRemainingProbability);
+
+  // And that winner should ALWAYS win.
+  EXPECT_EQ(winner, trial->group_name());
+}
+
 TEST_F(FieldTrialTest, MiddleProbabilities) {
   char name[] = " same name";
   bool false_event_seen = false;