Initial commit of cross connect integration test project (#3434)

Adding as a separate project so current integration tests stay working.

crossConnIntegrationTests/src/main/native/cpp/TestEnvironment.cpp

@@ -0,0 +1,70 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+#include <cstdlib>
+#include <thread>
+
+#include <fmt/core.h>
+#include <hal/HAL.h>
+
+#include "gtest/gtest.h"
+#include "mockds/MockDS.h"
+
+using namespace std::chrono_literals;
+
+class TestEnvironment : public testing::Environment {
+  bool m_alreadySetUp = false;
+  MockDS m_mockDS;
+
+ public:
+  TestEnvironment() {
+    // Only set up once. This allows gtest_repeat to be used to automatically
+    // repeat tests.
+    if (m_alreadySetUp) {
+      return;
+    }
+    m_alreadySetUp = true;
+
+    if (!HAL_Initialize(500, 0)) {
+      fmt::print(stderr, "FATAL ERROR: HAL could not be initialized\n");
+      std::exit(-1);
+    }
+
+    m_mockDS.Start();
+
+    // This sets up the network communications library to enable the driver
+    // station. After starting network coms, it will loop until the driver
+    // station returns that the robot is enabled, to ensure that tests will be
+    // able to run on the hardware.
+    HAL_ObserveUserProgramStarting();
+
+    fmt::print("Started coms\n");
+
+    int enableCounter = 0;
+
+    auto checkEnabled = []() {
+      HAL_ControlWord controlWord;
+      std::memset(&controlWord, 0, sizeof(controlWord));
+      HAL_GetControlWord(&controlWord);
+      return controlWord.enabled && controlWord.dsAttached;
+    };
+    while (!checkEnabled()) {
+      if (enableCounter > 50) {
+        // Robot did not enable properly after 5 seconds.
+        // Force exit
+        fmt::print(stderr, " Failed to enable. Aborting\n");
+        std::terminate();
+      }
+
+      std::this_thread::sleep_for(100ms);
+
+      fmt::print("Waiting for enable: {}\n", enableCounter++);
+    }
+  }
+
+  ~TestEnvironment() override { m_mockDS.Stop(); }
+};
+
+testing::Environment* const environment =
+    testing::AddGlobalTestEnvironment(new TestEnvironment);