Add user-friendly SimDeviceSim wrappers (#2150)

This makes unit testing with SimDevice devices much easier.

hal/src/test/native/cpp/sim/SimDeviceSimTest.cpp

@@ -0,0 +1,40 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2019 FIRST. All Rights Reserved.                             */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include <wpi/StringRef.h>
+
+#include "gtest/gtest.h"
+#include "hal/SimDevice.h"
+#include "simulation/SimDeviceSim.h"
+
+using namespace frc::sim;
+
+namespace hal {
+
+TEST(SimDeviceSimTests, TestBasic) {
+  SimDevice dev{"test"};
+  SimBoolean devBool = dev.CreateBoolean("bool", false, false);
+
+  SimDeviceSim sim{"test"};
+  SimBoolean simBool = sim.GetBoolean("bool");
+  EXPECT_FALSE(simBool.Get());
+  simBool.Set(true);
+  EXPECT_TRUE(devBool.Get());
+}
+
+TEST(SimDeviceSimTests, TestEnumerateDevices) {
+  SimDevice dev{"test"};
+
+  bool foundit = false;
+  SimDeviceSim::EnumerateDevices(
+      "te", [&](const char* name, HAL_SimDeviceHandle handle) {
+        if (wpi::StringRef(name) == "test") foundit = true;
+      });
+  EXPECT_TRUE(foundit);
+}
+
+}  // namespace hal