Move drive integration tests into wpilibj/src/test (#1836)

Also move drive and controller tests into subfolders.

wpilibc/src/test/native/cpp/controller/PIDInputOutputTest.cpp

@@ -0,0 +1,69 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2014-2019 FIRST. All Rights Reserved.                        */
+/* Open Source Software - may be modified and shared by FRC teams. The code   */
+/* must be accompanied by the FIRST BSD license file in the root directory of */
+/* the project.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "frc/controller/PIDController.h"
+#include "gtest/gtest.h"
+
+class PIDInputOutputTest : public testing::Test {
+ protected:
+  frc2::PIDController* controller;
+
+  void SetUp() override { controller = new frc2::PIDController(0, 0, 0); }
+
+  void TearDown() override { delete controller; }
+};
+
+TEST_F(PIDInputOutputTest, OutputRangeTest) {
+  controller->SetP(1);
+  controller->SetOutputRange(-50, 50);
+
+  EXPECT_DOUBLE_EQ(-50, controller->Calculate(100, 0));
+  EXPECT_DOUBLE_EQ(50, controller->Calculate(0, 100));
+}
+
+TEST_F(PIDInputOutputTest, InputRangeTest) {
+  controller->SetP(1);
+  controller->SetOutputRange(-1000, 1000);
+  controller->SetInputRange(-50, 50);
+
+  EXPECT_DOUBLE_EQ(-100, controller->Calculate(100, 0));
+  EXPECT_DOUBLE_EQ(50, controller->Calculate(0, 100));
+}
+
+TEST_F(PIDInputOutputTest, ContinuousInputTest) {
+  controller->SetP(1);
+  controller->EnableContinuousInput(-180, 180);
+
+  EXPECT_TRUE(controller->Calculate(-179, 179) < 0);
+}
+
+TEST_F(PIDInputOutputTest, ProportionalGainOutputTest) {
+  controller->SetP(4);
+
+  EXPECT_DOUBLE_EQ(-.1, controller->Calculate(.025, 0));
+}
+
+TEST_F(PIDInputOutputTest, IntegralGainOutputTest) {
+  controller->SetI(4);
+
+  double out = 0;
+
+  for (int i = 0; i < 5; i++) {
+    out = controller->Calculate(.025, 0);
+  }
+
+  EXPECT_DOUBLE_EQ(-.5 * controller->GetPeriod().to<double>(), out);
+}
+
+TEST_F(PIDInputOutputTest, DerivativeGainOutputTest) {
+  controller->SetD(4);
+
+  controller->Calculate(0, 0);
+
+  EXPECT_DOUBLE_EQ(-.01_s / controller->GetPeriod(),
+                   controller->Calculate(.0025, 0));
+}