Add failed_once category to Sheriff-O-Matic.

Tools/GardeningServer/model/test/ct-failure-group-tests.html

Index: Tools/GardeningServer/model/test/ct-failure-group-tests.html
diff --git a/Tools/GardeningServer/model/test/ct-failure-group-tests.html b/Tools/GardeningServer/model/test/ct-failure-group-tests.html
index 94ec87617e4b38cef5469a5c53b8004b97674f4e..0c408450a3b78f400ad90ce491ec2dcb9b074d87 100644
--- a/Tools/GardeningServer/model/test/ct-failure-group-tests.html
+++ b/Tools/GardeningServer/model/test/ct-failure-group-tests.html
@@ -35,6 +35,23 @@ describe('ct-failure-group', function() {
           [newFailureWithAnnotation({snoozeTime: Date.now() + 1000 * 1000})]));
       assert.equal(group.category, 'snoozed');
     });
+
+    it('should be "failedOnce" when there is only one failure', function() {
+      var failure = newFailureWithAnnotation();
+      failure.resultNodesByBuilder = {some_key: {failingBuildCount: 1}}
+      var group = new CTFailureGroup('', new CTSheriffFailureGroupData(
+          [failure]));
+      assert.equal(group.category, 'failedOnce');
+    });
+
+    it('should not be "failedOnce" when there is more than one failure', function() {
+      var failure = newFailureWithAnnotation();
+      failure.resultNodesByBuilder = {some_key: {failingBuildCount: 1},
+                                      other_key: {failingBuildCount: 1}}
+      var group = new CTFailureGroup('', new CTSheriffFailureGroupData(
+          [failure]));
+      assert.equal(group.category, 'default');
+    });
   });
 
   describe('snooze', function() {