Mod a hash of test names to determine a shard, rather than the test index.

base/test/launcher/test_launcher.cc

 // Copyright 2013 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.
 
 #include "base/test/launcher/test_launcher.h"
 
 #if defined(OS_POSIX)
 #include <fcntl.h>
 #endif
 
 #include "base/at_exit.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/environment.h"
 #include "base/file_util.h"
 #include "base/files/file_path.h"
 #include "base/files/scoped_file.h"
 #include "base/format_macros.h"
+#include "base/hash.h"
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
 #include "base/process/kill.h"
 #include "base/process/launch.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringize_macros.h"
@@ skipping 719 matching lines @@
 #if defined(ARCH_CPU_64_BITS)
   results_tracker_.AddGlobalTag("CPU_64_BITS");
 #endif
 
   return true;
 }
 
 void TestLauncher::RunTests() {
   testing::UnitTest* const unit_test = testing::UnitTest::GetInstance();
 
-  int num_runnable_tests = 0;
-
   std::vector<std::string> test_names;
 
   for (int i = 0; i < unit_test->total_test_case_count(); ++i) {
     const testing::TestCase* test_case = unit_test->GetTestCase(i);
     for (int j = 0; j < test_case->total_test_count(); ++j) {
       const testing::TestInfo* test_info = test_case->GetTestInfo(j);
       std::string test_name = test_info->test_case_name();
       test_name.append(".");
       test_name.append(test_info->name());
 
@@ skipping 27 matching lines @@
           excluded = true;
           break;
         }
       }
       if (excluded)
         continue;
 
       if (!launcher_delegate_->ShouldRunTest(test_case, test_info))
         continue;
 
-      if (num_runnable_tests++ % total_shards_ != shard_index_)
+      if (base::Hash(test_name) % total_shards_ !=
+          static_cast<uint32>(shard_index_)) {
         continue;
+      }
 
       test_names.push_back(test_name);
     }
   }
 
   test_started_count_ = launcher_delegate_->RunTests(this, test_names);
 
   if (test_started_count_ == 0) {
     fprintf(stdout, "0 tests run\n");
     fflush(stdout);
@@ skipping 257 matching lines @@
 
     g_live_processes.Get().erase(process_handle);
   }
 
   base::CloseProcessHandle(process_handle);
 
   return exit_code;
 }
 
 }  // namespace base