[wpilibj] Fix java async interrupts (#3559)

wpilibc/src/test/native/cpp/InterruptTest.cpp

@@ -0,0 +1,45 @@
+// 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 <atomic>
+
+#include <hal/HAL.h>
+
+#include "frc/AsynchronousInterrupt.h"
+#include "frc/DigitalInput.h"
+#include "frc/Timer.h"
+#include "frc/simulation/DIOSim.h"
+#include "gtest/gtest.h"
+
+namespace frc {
+using namespace frc::sim;
+TEST(InterruptTest, AsynchronousInterrupt) {
+  HAL_Initialize(500, 0);
+
+  std::atomic_int counter{0};
+  std::atomic_bool hasFired{false};
+
+  DigitalInput di{0};
+  AsynchronousInterrupt interrupt{di, [&](bool rising, bool falling) {
+                                    counter++;
+                                    hasFired = true;
+                                  }};
+
+  interrupt.Enable();
+  frc::Wait(0.5_s);
+  DIOSim digitalSim{di};
+  digitalSim.SetValue(false);
+  frc::Wait(20_ms);
+  digitalSim.SetValue(true);
+  frc::Wait(10_ms);
+
+  int count = 0;
+  while (!hasFired) {
+    frc::Wait(5_ms);
+    count++;
+    ASSERT_TRUE(count < 1000);
+  }
+  ASSERT_EQ(1, counter.load());
+}
+}  // namespace frc