Support filling in baselines from other platforms in rebaseline-cl.

third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_unittest.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.
 
 import json
 import optparse
 import unittest
 
 from webkitpy.common.net.buildbot import Build
 from webkitpy.common.net.layout_test_results import LayoutTestResults
@@ skipping 1169 matching lines @@
 
     def test_str_basic(self):
         test_baseline_set = TestBaselineSet(host=self.host)
         test_baseline_set.add('a/x.html', Build('MOCK Mac10.12'))
         test_baseline_set.add('a/x.html', Build('MOCK Win10'))
         self.assertEqual(
             str(test_baseline_set),
             ('<TestBaselineSet with:\n'
              '  a/x.html: Build(builder_name=\'MOCK Mac10.12\', build_number=None), test-mac-mac10.12\n'
              '  a/x.html: Build(builder_name=\'MOCK Win10\', build_number=None), test-win-win10>'))
+
+    def test_getters(self):
+        test_baseline_set = TestBaselineSet(host=self.host)
+        test_baseline_set.add('a/x.html', Build('MOCK Mac10.12'))
+        test_baseline_set.add('a/x.html', Build('MOCK Win10'))
+        self.assertEqual(test_baseline_set.test_prefixes(), ['a/x.html'])
+        self.assertEqual(
+            test_baseline_set.build_port_pairs('a/x.html'),
+            [
+                (Build(builder_name='MOCK Mac10.12'), 'test-mac-mac10.12'),
+                (Build(builder_name='MOCK Win10'), 'test-win-win10')
+            ])