[examples] Add unit testing infrastructure (#4646)

wpilibcExamples/src/main/cpp/examples/UnitTest/cpp/Robot.cpp

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+// 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 "Robot.h"
+
+/**
+ * This function is called periodically during operator control.
+ */
+void Robot::TeleopPeriodic() {
+  // Activate the intake while the trigger is held
+  if (m_joystick.GetTrigger()) {
+    m_intake.Activate(IntakeConstants::kIntakeSpeed);
+  } else {
+    m_intake.Activate(0);
+  }
+
+  // Toggle deploying the intake when the top button is pressed
+  if (m_joystick.GetTop()) {
+    if (m_intake.IsDeployed()) {
+      m_intake.Retract();
+    } else {
+      m_intake.Deploy();
+    }
+  }
+}
+
+#ifndef RUNNING_FRC_TESTS
+int main() {
+  return frc::StartRobot<Robot>();
+}
+#endif

wpilibcExamples/src/main/cpp/examples/UnitTest/cpp/subsystems/Intake.cpp

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+// 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 "subsystems/Intake.h"
+
+void Intake::Deploy() {
+  m_piston.Set(frc::DoubleSolenoid::Value::kForward);
+}
+
+void Intake::Retract() {
+  m_piston.Set(frc::DoubleSolenoid::Value::kReverse);
+  m_motor.Set(0);  // turn off the motor
+}
+
+void Intake::Activate(double speed) {
+  if (IsDeployed()) {
+    m_motor.Set(speed);
+  } else {  // if piston isn't open, do nothing
+    m_motor.Set(0);
+  }
+}
+
+bool Intake::IsDeployed() const {
+  return m_piston.Get() == frc::DoubleSolenoid::Value::kForward;
+}

wpilibcExamples/src/main/cpp/examples/UnitTest/include/Constants.h

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+// 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.
+
+#pragma once
+
+/**
+ * The Constants header provides a convenient place for teams to hold robot-wide
+ * numerical or bool constants.  This should not be used for any other purpose.
+ *
+ * It is generally a good idea to place constants into subsystem- or
+ * command-specific namespaces within this header, which can then be used where
+ * they are needed.
+ */
+
+namespace IntakeConstants {
+constexpr int kMotorPort = 1;
+
+constexpr int kPistonFwdChannel = 0;
+constexpr int kPistonRevChannel = 1;
+constexpr double kIntakeSpeed = 0.5;
+}  // namespace IntakeConstants
+
+namespace OperatorConstants {
+constexpr int kJoystickIndex = 0;
+}  // namespace OperatorConstants

wpilibcExamples/src/main/cpp/examples/UnitTest/include/Robot.h

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+// 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.
+
+#pragma once
+
+#include <frc/Joystick.h>
+#include <frc/TimedRobot.h>
+
+#include "Constants.h"
+#include "subsystems/Intake.h"
+
+class Robot : public frc::TimedRobot {
+ public:
+  void TeleopPeriodic() override;
+
+ private:
+  Intake m_intake;
+  frc::Joystick m_joystick{OperatorConstants::kJoystickIndex};
+};

wpilibcExamples/src/main/cpp/examples/UnitTest/include/subsystems/Intake.h

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+// 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.
+
+#pragma once
+
+#include <frc/DoubleSolenoid.h>
+#include <frc/motorcontrol/PWMSparkMax.h>
+
+#include "Constants.h"
+
+class Intake {
+ public:
+  void Deploy();
+  void Retract();
+  void Activate(double speed);
+  bool IsDeployed() const;
+
+ private:
+  frc::PWMSparkMax m_motor{IntakeConstants::kMotorPort};
+  frc::DoubleSolenoid m_piston{frc::PneumaticsModuleType::CTREPCM,
+                               IntakeConstants::kPistonFwdChannel,
+                               IntakeConstants::kPistonRevChannel};
+};