[Findit] Initial code of findit for crash. Add scorers to apply heuristic rules.

appengine/findit/crash/scorers/test/aggregator_test.py

+# Copyright 2016 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.
+
+from crash.callstack import StackFrame
+from crash.results import MatchResult
+from crash.scorers.aggregator import Aggregator
+from crash.scorers.min_distance import MinDistance
+from crash.scorers.test.scorer_test_suite import ScorerTestSuite
+from crash.scorers.top_frame_index import TopFrameIndex
+
+
+class AggregatorTest(ScorerTestSuite):
+
+  def testScoreAndReason(self):
+    result = MatchResult(self._GetDummyChangeLog(), 'src/', '')
+    result.file_to_stack_infos = {
+        'a.cc': [(StackFrame(0, 'src/', '', 'func', 'a.cc', [7]), 0)]
+    }
+    result.min_distance = 0
+
+    aggregator = Aggregator([TopFrameIndex(), MinDistance()])
+    aggregator.ScoreAndReason(result)
+
+    self.assertEqual(result.confidence, 1)
+    self.assertEqual(result.reason,
+                     ('1. Top frame changed is frame #0 (score: 1)\n'
+                      '2. Minimum distance to crashed line is 0 (score: 1)\n'
+                      '\nChanged file a.cc which crashed in func (#0)'))