Google Test: How to run fixture only once for multiple tests?

Question

I am trying to test a http client using gtest. I want to test this client with my own http server. I have a small python server. Test cases would be client sending various requests to this python server. Is there a way to start the server before all tests run and destroy that server after tests?

I am trying to use gtest fixture as shown here; by creating a new process in SetUp and killing it in TearDown. But it looks like the these calls are made for every test.

class Base: public ::testing::Test {
public:
    pid_t child_pid = 0;
    void SetUp() {
        char *cmd = "/usr/bin/python";
        char *arg[] = {cmd, "./http_server.py", NULL};
        child_pid = fork();
        if ( child_pid == 0) {
            execvp(cmd, arg);
            std::cout << "Failed to exec child: " << child_pid << std::endl;
            exit(-1);
        } else if (child_pid < 0) {
            std::cout << "Failed to fork child: " << child_pid << std::endl;
        } else {
            std::cout << "Child HTTP server pid: " << child_pid << std::endl;
        }
    }

    void TearDown() {
        std::cout << "Killing child pid: " << child_pid << std::endl;
        kill(child_pid, SIGKILL);
    }
};

TEST_F(Base, test_1) {
    // http client downloading url
}

TEST_F(Base, test_2) {
    // http client downloading url
}

Answer 1

If you want to have single connection per test suite (single test fixture), then you can define static methods SetUpTestSuite() and TearDownTestSuite() in your fixture class (documentation)

class Base: public ::testing::Test {
public:
    static void SetUpTestSuite() {
        //code here
    }

    static void TearDownTestSuite() {
        //code here
    }
};

---

If you'd rather have single instance for all the tests suites, you can use global SetUp and TearDown (documentation)

class MyEnvironment: public ::testing::Environment
{
public:
  virtual ~MyEnvironment() = default;

  // Override this to define how to set up the environment.
  virtual void SetUp() {}

  // Override this to define how to tear down the environment.
  virtual void TearDown() {}
};

Then you need to register the environment of yours in GoogleTest, preferable in main() (before RUN_ALL_TESTS is called):

//don't use std::unique_ptr! GoogleTest takes ownership of the pointer and will clean up
MyEnvironment* env = new MyEnvironment(); 
::testing::AddGlobalTestEnvironment(env);

---

Note: The code wasn't tested.