[wpilib] Add Timer tests (#3595)

wpilibj/src/test/java/edu/wpi/first/wpilibj/TimerTest.java

@@ -0,0 +1,132 @@
+// 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.
+
+package edu.wpi.first.wpilibj;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import edu.wpi.first.hal.HAL;
+import edu.wpi.first.wpilibj.simulation.SimHooks;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.parallel.ResourceLock;
+
+class TimerTest {
+  @BeforeEach
+  void setup() {
+    HAL.initialize(500, 0);
+    SimHooks.pauseTiming();
+    SimHooks.restartTiming();
+  }
+
+  @AfterEach
+  void cleanup() {
+    SimHooks.resumeTiming();
+  }
+
+  @Test
+  @ResourceLock("timing")
+  void startStopTest() {
+    var timer = new Timer();
+
+    // Verify timer is initialized as stopped
+    assertEquals(timer.get(), 0.0);
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.0);
+
+    // Verify timer increments after it's started
+    timer.start();
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.5, 1e-9);
+
+    // Verify timer stops incrementing after it's stopped
+    timer.stop();
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.5, 1e-9);
+  }
+
+  @Test
+  @ResourceLock("timing")
+  void resetTest() {
+    var timer = new Timer();
+    timer.start();
+
+    // Advance timer to 500 ms
+    assertEquals(timer.get(), 0.0);
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.5, 1e-9);
+
+    // Verify timer reports 0 ms after reset
+    timer.reset();
+    assertEquals(timer.get(), 0.0);
+
+    // Verify timer continues incrementing
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.5, 1e-9);
+
+    // Verify timer doesn't start incrementing after reset if it was stopped
+    timer.stop();
+    timer.reset();
+    SimHooks.stepTiming(0.5);
+    assertEquals(timer.get(), 0.0);
+  }
+
+  @Test
+  @ResourceLock("timing")
+  void hasElapsedTest() {
+    var timer = new Timer();
+
+    // Verify 0 ms has elapsed since timer hasn't started
+    assertTrue(timer.hasElapsed(0.0));
+
+    // Verify timer doesn't report elapsed time when stopped
+    SimHooks.stepTiming(0.5);
+    assertFalse(timer.hasElapsed(0.4));
+
+    timer.start();
+
+    // Verify timer reports >= 400 ms has elapsed after multiple calls
+    SimHooks.stepTiming(0.5);
+    assertTrue(timer.hasElapsed(0.4));
+    assertTrue(timer.hasElapsed(0.4));
+  }
+
+  @Test
+  @ResourceLock("timing")
+  void advanceIfElapsedTest() {
+    var timer = new Timer();
+
+    // Verify 0 ms has elapsed since timer hasn't started
+    assertTrue(timer.advanceIfElapsed(0.0));
+
+    // Verify timer doesn't report elapsed time when stopped
+    SimHooks.stepTiming(0.5);
+    assertFalse(timer.advanceIfElapsed(0.4));
+
+    timer.start();
+
+    // Verify timer reports >= 400 ms has elapsed for only first call
+    SimHooks.stepTiming(0.5);
+    assertTrue(timer.advanceIfElapsed(0.4));
+    assertFalse(timer.advanceIfElapsed(0.4));
+
+    // Verify timer reports >= 400 ms has elapsed for two calls
+    SimHooks.stepTiming(1.0);
+    assertTrue(timer.advanceIfElapsed(0.4));
+    assertTrue(timer.advanceIfElapsed(0.4));
+    assertFalse(timer.advanceIfElapsed(0.4));
+  }
+
+  @Test
+  @ResourceLock("timing")
+  void getFPGATimestampTest() {
+    double start = Timer.getFPGATimestamp();
+    SimHooks.stepTiming(0.5);
+    double end = Timer.getFPGATimestamp();
+    assertEquals(start + 0.5, end, 1e-9);
+  }
+}