[examples] Add unit testing infrastructure (#4646)

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

@@ -0,0 +1,17 @@
+// 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 <hal/HALBase.h>
+
+#include "gtest/gtest.h"
+
+/**
+ * Runs all unit tests.
+ */
+int main(int argc, char** argv) {
+  HAL_Initialize(500, 0);
+  ::testing::InitGoogleTest(&argc, argv);
+  int ret = RUN_ALL_TESTS();
+  return ret;
+}

wpilibcExamples/src/test/cpp/examples/UnitTest/cpp/subsystems/IntakeTest.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 <gtest/gtest.h>
+
+#include <frc/DoubleSolenoid.h>
+#include <frc/simulation/DoubleSolenoidSim.h>
+#include <frc/simulation/PWMSim.h>
+
+#include "Constants.h"
+#include "subsystems/Intake.h"
+
+class IntakeTest : public testing::Test {
+ protected:
+  Intake intake;  // create our intake
+  frc::sim::PWMSim simMotor{
+      IntakeConstants::kMotorPort};  // create our simulation PWM
+  frc::sim::DoubleSolenoidSim simPiston{
+      frc::PneumaticsModuleType::CTREPCM, IntakeConstants::kPistonFwdChannel,
+      IntakeConstants::kPistonRevChannel};  // create our simulation solenoid
+};
+
+TEST_F(IntakeTest, DoesntWorkWhenClosed) {
+  intake.Retract();      // close the intake
+  intake.Activate(0.5);  // try to activate the motor
+  EXPECT_DOUBLE_EQ(
+      0.0,
+      simMotor.GetSpeed());  // make sure that the value set to the motor is 0
+}
+
+TEST_F(IntakeTest, WorksWhenOpen) {
+  intake.Deploy();
+  intake.Activate(0.5);
+  EXPECT_DOUBLE_EQ(0.5, simMotor.GetSpeed());
+}
+
+TEST_F(IntakeTest, Retract) {
+  intake.Retract();
+  EXPECT_EQ(frc::DoubleSolenoid::Value::kReverse, simPiston.Get());
+}
+
+TEST_F(IntakeTest, Deploy) {
+  intake.Deploy();
+  EXPECT_EQ(frc::DoubleSolenoid::Value::kForward, simPiston.Get());
+}