[Interpreter] Report hottest bytecodes in bytecode_dispatches_report.py

tools/ignition/bytecode_dispatches_report_test.py

 # Copyright 2016 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import bytecode_dispatches_report as bdr
 import unittest
 
 
 class BytecodeDispatchesReportTest(unittest.TestCase):
   def test_find_top_counters(self):
@@ skipping 11 matching lines @@
   def test_build_counters_matrix(self):
     counters_matrix, xlabels, ylabels = bdr.build_counters_matrix({
       "a": {"a": 10, "b":  8, "c":  7},
       "b": {"a":  1, "c":  4},
       "c": {"a": 42, "b": 12, "c": 99}})
     self.assertTrue((counters_matrix == [[42, 12, 99],
                                          [ 1,  0,  4],
                                          [10,  8,  7]]).all())
     self.assertListEqual(xlabels, ['a', 'b', 'c'])
     self.assertListEqual(ylabels, ['c', 'b', 'a'])
+
+  def test_find_top_dispatch_sources(self):
+    top_dispatch_sources = bdr.find_top_bytecodes({
+      "a": {"a": 10, "b":  8, "c":  7},
+      "b": {"a":  1, "c":  4},
+      "c": {"a": 42, "b": 12, "c": 99}
+    })
+    self.assertListEqual(top_dispatch_sources, [
+      ('c', 153),
+      ('a',  25),
+      ('b',   5)
+    ])