testing/multiprocess_func_list.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef TESTING_MULTIPROCESS_FUNC_LIST_H_
   6 #define TESTING_MULTIPROCESS_FUNC_LIST_H_
   7
   8 #include <string>
   9
  10 // This file provides the plumbing to register functions to be executed
  11 // as the main function of a child process in a multi-process test.
  12 // This complements the MultiProcessTest class which provides facilities
  13 // for launching such tests.
  14 //
  15 // The MULTIPROCESS_TEST_MAIN() macro registers a string -> func_ptr mapping
  16 // by creating a new global instance of the AppendMultiProcessTest() class
  17 // this means that by the time that we reach our main() function the mapping
  18 // is already in place.
  19 //
  20 // Example usage:
  21 //  MULTIPROCESS_TEST_MAIN(a_test_func) {
  22 //    // Code here runs in a child process.
  23 //    return 0;
  24 //  }
  25 //
  26 // The prototype of a_test_func is implicitly
  27 //   int test_main_func_name();
  28
  29 namespace multi_process_function_list {
  30
  31 // Type for child process main functions.
  32 typedef int (*TestMainFunctionPtr)();
  33
  34 // Type for child setup functions.
  35 typedef void (*SetupFunctionPtr)();
  36
  37 // Helper class to append a test function to the global mapping.
  38 // Used by the MULTIPROCESS_TEST_MAIN macro.
  39 class AppendMultiProcessTest {
  40  public:
  41   // |main_func_ptr| is the main function that is run in the child process.
  42   // |setup_func_ptr| is a function run when the global mapping is added.
  43   AppendMultiProcessTest(std::string test_name,
  44                          TestMainFunctionPtr main_func_ptr,
  45                          SetupFunctionPtr setup_func_ptr);
  46 };
  47
  48 // Invoke the main function of a test previously registered with
  49 // MULTIPROCESS_TEST_MAIN()
  50 int InvokeChildProcessTest(std::string test_name);
  51
  52 // This macro creates a global MultiProcessTest::AppendMultiProcessTest object
  53 // whose constructor does the work of adding the global mapping.
  54 #define MULTIPROCESS_TEST_MAIN(test_main) \
  55   MULTIPROCESS_TEST_MAIN_WITH_SETUP(test_main, NULL)
  56
  57 // Same as above but lets callers specify a setup method that is run in the
  58 // child process, just before the main function is run.  This facilitates
  59 // adding a generic one-time setup function for multiple tests.
  60 #define MULTIPROCESS_TEST_MAIN_WITH_SETUP(test_main, test_setup) \
  61   int test_main(); \
  62   namespace { \
  63     multi_process_function_list::AppendMultiProcessTest \
  64     AddMultiProcessTest##_##test_main(#test_main, (test_main), (test_setup)); \
  65   } \
  66   int test_main()
  67
  68 }  // namespace multi_process_function_list
  69
  70 #endif  // TESTING_MULTIPROCESS_FUNC_LIST_H_