[examples] Add unit testing infrastructure (#4646)

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/examples/examples.json

@@ -733,6 +733,17 @@
     "mainclass": "Main",
     "commandversion": 2
   },
+  {
+    "name": "UnitTesting",
+    "description": "Demonstrates basic unit testing for a robot project.",
+    "tags": [
+      "Testing"
+    ],
+    "foldername": "unittest",
+    "gradlebase": "java",
+    "mainclass": "Main",
+    "commandversion": 2
+  },
   {
     "name": "DifferentialDrivePoseEstimator",
     "description": "Demonstrates the use of the DifferentialDrivePoseEstimator as a replacement for differential drive odometry.",

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/examples/unittest/Constants.java

@@ -0,0 +1,25 @@
+// 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.examples.unittest;
+
+/**
+ * The Constants class provides a convenient place for teams to hold robot-wide numerical or boolean
+ * constants. This class should not be used for any other purpose. All constants should be declared
+ * globally (i.e. public static). Do not put anything functional in this class.
+ *
+ * <p>It is advised to statically import this class (or one of its inner classes) wherever the
+ * constants are needed, to reduce verbosity.
+ */
+public final class Constants {
+  public static final int kJoystickIndex = 0;
+
+  public static final class IntakeConstants {
+    public static final int kMotorPort = 1;
+
+    public static final int kPistonFwdChannel = 0;
+    public static final int kPistonRevChannel = 1;
+    public static final double kIntakeSpeed = 0.5;
+  }
+}

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/examples/unittest/Main.java

@@ -0,0 +1,25 @@
+// 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.examples.unittest;
+
+import edu.wpi.first.wpilibj.RobotBase;
+
+/**
+ * Do NOT add any static variables to this class, or any initialization at all. Unless you know what
+ * you are doing, do not modify this file except to change the parameter class to the startRobot
+ * call.
+ */
+public final class Main {
+  private Main() {}
+
+  /**
+   * Main initialization function. Do not perform any initialization here.
+   *
+   * <p>If you change your main robot class, change the parameter type.
+   */
+  public static void main(String... args) {
+    RobotBase.startRobot(Robot::new);
+  }
+}

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/examples/unittest/Robot.java

@@ -0,0 +1,41 @@
+// 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.examples.unittest;
+
+import edu.wpi.first.wpilibj.Joystick;
+import edu.wpi.first.wpilibj.TimedRobot;
+import edu.wpi.first.wpilibj.examples.unittest.Constants.IntakeConstants;
+import edu.wpi.first.wpilibj.examples.unittest.subsystems.Intake;
+
+/**
+ * The VM is configured to automatically run this class, and to call the functions corresponding to
+ * each mode, as described in the TimedRobot documentation. If you change the name of this class or
+ * the package after creating this project, you must also update the build.gradle file in the
+ * project.
+ */
+public class Robot extends TimedRobot {
+  private Intake m_intake = new Intake();
+  private Joystick m_joystick = new Joystick(Constants.kJoystickIndex);
+
+  /** This function is called periodically during operator control. */
+  @Override
+  public void 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();
+      }
+    }
+  }
+}

wpilibjExamples/src/main/java/edu/wpi/first/wpilibj/examples/unittest/subsystems/Intake.java

@@ -0,0 +1,51 @@
+// 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.examples.unittest.subsystems;
+
+import edu.wpi.first.wpilibj.DoubleSolenoid;
+import edu.wpi.first.wpilibj.PneumaticsModuleType;
+import edu.wpi.first.wpilibj.examples.unittest.Constants.IntakeConstants;
+import edu.wpi.first.wpilibj.motorcontrol.PWMSparkMax;
+
+public class Intake implements AutoCloseable {
+  private final PWMSparkMax m_motor;
+  private final DoubleSolenoid m_piston;
+
+  public Intake() {
+    m_motor = new PWMSparkMax(IntakeConstants.kMotorPort);
+    m_piston =
+        new DoubleSolenoid(
+            PneumaticsModuleType.CTREPCM,
+            IntakeConstants.kPistonFwdChannel,
+            IntakeConstants.kPistonRevChannel);
+  }
+
+  public void deploy() {
+    m_piston.set(DoubleSolenoid.Value.kForward);
+  }
+
+  public void retract() {
+    m_piston.set(DoubleSolenoid.Value.kReverse);
+    m_motor.set(0); // turn off the motor
+  }
+
+  public void activate(double speed) {
+    if (isDeployed()) {
+      m_motor.set(speed);
+    } else { // if piston isn't open, do nothing
+      m_motor.set(0);
+    }
+  }
+
+  public boolean isDeployed() {
+    return m_piston.get() == DoubleSolenoid.Value.kForward;
+  }
+
+  @Override
+  public void close() throws Exception {
+    m_piston.close();
+    m_motor.close();
+  }
+}

wpilibjExamples/src/test/java/edu/wpi/first/wpilibj/examples/unittest/subsystems/IntakeTest.java

@@ -0,0 +1,70 @@
+// 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.examples.unittest.subsystems;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import edu.wpi.first.hal.HAL;
+import edu.wpi.first.wpilibj.DoubleSolenoid;
+import edu.wpi.first.wpilibj.PneumaticsModuleType;
+import edu.wpi.first.wpilibj.examples.unittest.Constants.IntakeConstants;
+import edu.wpi.first.wpilibj.simulation.DoubleSolenoidSim;
+import edu.wpi.first.wpilibj.simulation.PWMSim;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class IntakeTest {
+  static final double DELTA = 1e-2; // acceptable deviation range
+  Intake m_intake;
+  PWMSim m_simMotor;
+  DoubleSolenoidSim m_simPiston;
+
+  @BeforeEach // this method will run before each test
+  void setup() {
+    assert HAL.initialize(500, 0); // initialize the HAL, crash if failed
+    m_intake = new Intake(); // create our intake
+    m_simMotor =
+        new PWMSim(IntakeConstants.kMotorPort); // create our simulation PWM motor controller
+    m_simPiston =
+        new DoubleSolenoidSim(
+            PneumaticsModuleType.CTREPCM,
+            IntakeConstants.kPistonFwdChannel,
+            IntakeConstants.kPistonRevChannel); // create our simulation solenoid
+  }
+
+  @SuppressWarnings("PMD.SignatureDeclareThrowsException")
+  @AfterEach // this method will run after each test
+  void shutdown() throws Exception {
+    m_intake.close(); // destroy our intake object
+  }
+
+  @Test // marks this method as a test
+  void doesntWorkWhenClosed() {
+    m_intake.retract(); // close the intake
+    m_intake.activate(0.5); // try to activate the motor
+    assertEquals(
+        0.0, m_simMotor.getSpeed(), DELTA); // make sure that the value set to the motor is 0
+  }
+
+  @Test
+  void worksWhenOpen() {
+    m_intake.deploy();
+    m_intake.activate(0.5);
+    assertEquals(0.5, m_simMotor.getSpeed(), DELTA);
+  }
+
+  @Test
+  void retractTest() {
+    m_intake.retract();
+    assertEquals(DoubleSolenoid.Value.kReverse, m_simPiston.get());
+  }
+
+  @Test
+  void deployTest() {
+    m_intake.deploy();
+    assertEquals(DoubleSolenoid.Value.kForward, m_simPiston.get());
+  }
+}