[wpilib] Add Timer tests (#3595)

wpilibc/src/test/native/cpp/TimerTest.cpp

@@ -0,0 +1,115 @@
+// 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 "frc/Timer.h"  // NOLINT(build/include_order)
+
+#include "frc/simulation/SimHooks.h"
+#include "gtest/gtest.h"
+
+using namespace frc;
+
+namespace {
+class TimerTest : public ::testing::Test {
+ protected:
+  void SetUp() override {
+    frc::sim::PauseTiming();
+    frc::sim::RestartTiming();
+  }
+
+  void TearDown() override { frc::sim::ResumeTiming(); }
+};
+
+}  // namespace
+
+TEST_F(TimerTest, StartStop) {
+  Timer timer;
+
+  // Verify timer is initialized as stopped
+  EXPECT_EQ(timer.Get(), 0_s);
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 0_s);
+
+  // Verify timer increments after it's started
+  timer.Start();
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 500_ms);
+
+  // Verify timer stops incrementing after it's stopped
+  timer.Stop();
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 500_ms);
+}
+
+TEST_F(TimerTest, Reset) {
+  Timer timer;
+  timer.Start();
+
+  // Advance timer to 500 ms
+  EXPECT_EQ(timer.Get(), 0_s);
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 500_ms);
+
+  // Verify timer reports 0 ms after reset
+  timer.Reset();
+  EXPECT_EQ(timer.Get(), 0_s);
+
+  // Verify timer continues incrementing
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 500_ms);
+
+  // Verify timer doesn't start incrementing after reset if it was stopped
+  timer.Stop();
+  timer.Reset();
+  frc::sim::StepTiming(500_ms);
+  EXPECT_EQ(timer.Get(), 0_ms);
+}
+
+TEST_F(TimerTest, HasElapsed) {
+  Timer timer;
+
+  // Verify 0 ms has elapsed since timer hasn't started
+  EXPECT_TRUE(timer.HasElapsed(0_s));
+
+  // Verify timer doesn't report elapsed time when stopped
+  frc::sim::StepTiming(500_ms);
+  EXPECT_FALSE(timer.HasElapsed(400_ms));
+
+  timer.Start();
+
+  // Verify timer reports >= 400 ms has elapsed after multiple calls
+  frc::sim::StepTiming(500_ms);
+  EXPECT_TRUE(timer.HasElapsed(400_ms));
+  EXPECT_TRUE(timer.HasElapsed(400_ms));
+}
+
+TEST_F(TimerTest, AdvanceIfElapsed) {
+  Timer timer;
+
+  // Verify 0 ms has elapsed since timer hasn't started
+  EXPECT_TRUE(timer.AdvanceIfElapsed(0_s));
+
+  // Verify timer doesn't report elapsed time when stopped
+  frc::sim::StepTiming(500_ms);
+  EXPECT_FALSE(timer.AdvanceIfElapsed(400_ms));
+
+  timer.Start();
+
+  // Verify timer reports >= 400 ms has elapsed for only first call
+  frc::sim::StepTiming(500_ms);
+  EXPECT_TRUE(timer.AdvanceIfElapsed(400_ms));
+  EXPECT_FALSE(timer.AdvanceIfElapsed(400_ms));
+
+  // Verify timer reports >= 400 ms has elapsed for two calls
+  frc::sim::StepTiming(1_s);
+  EXPECT_TRUE(timer.AdvanceIfElapsed(400_ms));
+  EXPECT_TRUE(timer.AdvanceIfElapsed(400_ms));
+  EXPECT_FALSE(timer.AdvanceIfElapsed(400_ms));
+}
+
+TEST_F(TimerTest, GetFPGATimestamp) {
+  auto start = frc::Timer::GetFPGATimestamp();
+  frc::sim::StepTiming(500_ms);
+  auto end = frc::Timer::GetFPGATimestamp();
+  EXPECT_EQ(start + 500_ms, end);
+}