googletest：sample9分析

测试文件

GoogleTest提供了一套event listener API，sample9展示如何用这套API，实现替代console输出，以及如何用UnitTest反射API 枚举 test suites和test并检查其结果.

必须继承自testing::TestEventListener 或 testing::EmptyEventListener，前者是一个纯抽象类，必须实现所有接口，后者只需要重写所关心的接口.

当一个事件触发时，它的上下文(context)作为参数送入处理函数.

UnitTest 反映了整个测试程序的状态
TestSuite 测试集的状态
TestInfo 具体测试的状态
TestPartResult 测试结果

如何使用Event Listener监听test?

定义一个Event Listener

// Provides alternative output mode which produces minimal amount of
// information about tests.
class TersePrinter : public EmptyTestEventListener {
 private:
  // Called before any test activity starts.
  void OnTestProgramStart(const UnitTest& /* unit_test */) override {}

  // Called after all test activities have ended.
  void OnTestProgramEnd(const UnitTest& unit_test) override {
    fprintf(stdout, "TEST %s\n", unit_test.Passed() ? "PASSED" : "FAILED");
    fflush(stdout);
  }

  // Called before a test starts.
  void OnTestStart(const TestInfo& test_info) override {
    fprintf(stdout, "*** Test %s.%s starting.\n", test_info.test_suite_name(),
            test_info.name());
    fflush(stdout);
  }

  // Called after a failed assertion or a SUCCEED() invocation.
  void OnTestPartResult(const TestPartResult& test_part_result) override {
    fprintf(stdout, "%s in %s:%d\n%s\n",
            test_part_result.failed() ? "*** Failure" : "Success",
            test_part_result.file_name(), test_part_result.line_number(),
            test_part_result.summary());
    fflush(stdout);
  }

  // Called after a test ends.
  void OnTestEnd(const TestInfo& test_info) override {
    fprintf(stdout, "*** Test %s.%s ending.\n", test_info.test_suite_name(),
            test_info.name());
    fflush(stdout);
  }
};  // class TersePrinter

注册Event Listener

main函数中，用listeners.Append()将自定义监听器注册到GoogleTest中.

int main(int argc, char** argv) {
  InitGoogleTest(&argc, argv);

  bool terse_output = false;
  if (argc > 1 && strcmp(argv[1], "--terse_output") == 0)
    terse_output = true;
  else
    printf("%s\n",
           "Run this program with --terse_output to change the way "
           "it prints its output.");

  UnitTest& unit_test = *UnitTest::GetInstance();

  // If we are given the --terse_output command line flag, suppresses the
  // standard output and attaches own result printer.
  if (terse_output) {
    TestEventListeners& listeners = unit_test.listeners();

    // Removes the default console output listener from the list so it will
    // not receive events from Google Test and won't print any output. Since
    // this operation transfers ownership of the listener to the caller we
    // have to delete it as well.
    delete listeners.Release(listeners.default_result_printer());

    // Adds the custom output listener to the list. It will now receive
    // events from Google Test and print the alternative output. We don't
    // have to worry about deleting it since Google Test assumes ownership
    // over it after adding it to the list.
    listeners.Append(new TersePrinter);
  }
  ...
}

注意：GTest本身有默认的处理函数，需要将其关闭

delete listeners.Release(listeners.default_result_printer());

设计test

下面是用户自定义的test

TEST(CustomOutputTest, PrintsMessage) {
  printf("Printing something from the test body...\n");
}

TEST(CustomOutputTest, Succeeds) {
  SUCCEED() << "SUCCEED() has been invoked from here";
}

TEST(CustomOutputTest, Fails) {
  EXPECT_EQ(1, 2)
      << "This test fails in order to demonstrate alternative failure messages";
}

运行test

执行RUN_ALL_TESTS()，运行所有test.

int main(int argc, char** argv) {
  // 注册Event Listner
  ...
  RUN_ALL_TESTS();
  ...
}

如何通过反射API枚举test suite及获取test检查结果？

1）获取 UnitTest 实例

用testing::UnitTest::GetInstance()获取当前测试程序的UnitTest实例.

2）遍历test suite

用UnitTest::total_test_suite_count()获取test suite的总数，并通过 UnitTest::GetTestSuite(i) 获取每个test suite.

3）遍历test

对于每个test suite，使用TestSuite::total_test_count()获取test的总数，并通过 TestSuite::GetTestInfo(j)获取每个test执行信息，如执行结果，test名称等信息.

4）输出test suite, test信息

如：
test_suite->name() 返回test suite的名称；
test_info->name() 返回test的名称.

int main(int argc, char* argv[]) {
  UnitTest& unit_test = *UnitTest::GetInstance();
  ...

  // This is an example of using the UnitTest reflection API to inspect test
  // results. Here we discount failures from the tests we expected to fail.
  int unexpectedly_failed_tests = 0;
  for (int i = 0; i < unit_test.total_test_suite_count(); ++i) {
    const testing::TestSuite& test_suite = *unit_test.GetTestSuite(i);
    for (int j = 0; j < test_suite.total_test_count(); ++j) {
      const TestInfo& test_info = *test_suite.GetTestInfo(j);
      // Counts failed tests that were not meant to fail (those without
      // 'Fails' in the name).
      if (test_info.result()->Failed() &&
          strcmp(test_info.name(), "Fails") != 0) {
        unexpectedly_failed_tests++;
      }
    }
  }

  // Test that were meant to fail should not affect the test program outcome.
  if (unexpectedly_failed_tests == 0) ret_val = 0;
  ...
}

sample9 unittest运行结果：

Run this program with --terse_output to change the way it prints its output.
[==========] Running 3 tests from 1 test suite.
[----------] Global test environment set-up.
[----------] 3 tests from CustomOutputTest
[ RUN      ] CustomOutputTest.PrintsMessage
Printing something from the test body...
[       OK ] CustomOutputTest.PrintsMessage (0 ms)
[ RUN      ] CustomOutputTest.Succeeds
[       OK ] CustomOutputTest.Succeeds (1 ms)
[ RUN      ] CustomOutputTest.Fails
D:\Programs\googletest\googletest-main\googletest\samples\sample9_unittest.cc(91): error: Expected equality of these values:
  1
  2
This test fails in order to demonstrate alternative failure messages

[  FAILED  ] CustomOutputTest.Fails (0 ms)
[----------] 3 tests from CustomOutputTest (2 ms total)

[----------] Global test environment tear-down
[==========] 3 tests from 1 test suite ran. (5 ms total)
[  PASSED  ] 2 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] CustomOutputTest.Fails

 1 FAILED TEST

参考

GoogleTest advanced document

EmptyTestEventListener

posted @ 2025-03-02 18:22 明明1109 阅读(46) 评论(0) 收藏举报

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