Adding a simple codelab. Hopefully this can be useful in training.

Change-Id: I3bab489d66969e78fd527c7f8f4361228bb20be9
diff --git a/frc971/codelab/basic_test.cc b/frc971/codelab/basic_test.cc
new file mode 100644
index 0000000..0acf9e7
--- /dev/null
+++ b/frc971/codelab/basic_test.cc
@@ -0,0 +1,170 @@
+#include "frc971/codelab/basic.h"
+
+#include <unistd.h>
+
+#include <chrono>
+#include <memory>
+
+#include "aos/common/controls/control_loop_test.h"
+#include "aos/common/queue.h"
+#include "frc971/codelab/basic.q.h"
+#include "frc971/control_loops/team_number_test_environment.h"
+#include "gtest/gtest.h"
+
+namespace frc971 {
+namespace codelab {
+namespace testing {
+
+// Class which simulates stuff and sends out queue messages with the
+// position.
+class BasicSimulation {
+ public:
+  BasicSimulation()
+      : basic_queue_(".frc971.codelab.basic_queue", 0x78d8e372,
+                     ".frc971.codelab.basic_queue.goal",
+                     ".frc971.codelab.basic_queue.position",
+                     ".frc971.codelab.basic_queue.output",
+                     ".frc971.codelab.basic_queue.status") {}
+
+  // Sends a queue message with the position data.
+  void SendPositionMessage() {
+    ::aos::ScopedMessagePtr<BasicQueue::Position> position =
+        basic_queue_.position.MakeMessage();
+
+    position->limit_sensor = limit_sensor_;
+
+    position.Send();
+  }
+
+  void VerifyResults(double voltage, bool status) {
+    basic_queue_.output.FetchLatest();
+    basic_queue_.status.FetchLatest();
+
+    ASSERT_TRUE(basic_queue_.output.get() != nullptr);
+    ASSERT_TRUE(basic_queue_.status.get() != nullptr);
+
+    EXPECT_EQ(basic_queue_.output->intake_voltage, voltage);
+    EXPECT_EQ(basic_queue_.status->intake_complete, status);
+  }
+
+  void set_limit_sensor(bool value) { limit_sensor_ = value; }
+
+  // Simulates basic control loop for a single timestep.
+  void Simulate() { EXPECT_TRUE(basic_queue_.output.FetchLatest()); }
+
+ private:
+  BasicQueue basic_queue_;
+  bool limit_sensor_ = false;
+};
+
+class BasicControlLoopTest : public ::aos::testing::ControlLoopTest {
+ public:
+  BasicControlLoopTest()
+      : basic_queue_(".frc971.codelab.basic_queue", 0x78d8e372,
+                     ".frc971.codelab.basic_queue.goal",
+                     ".frc971.codelab.basic_queue.position",
+                     ".frc971.codelab.basic_queue.output",
+                     ".frc971.codelab.basic_queue.status"),
+        basic_loop_(&basic_queue_) {
+    set_team_id(control_loops::testing::kTeamNumber);
+  }
+
+  // Runs one iteration of the whole simulation.
+  void RunIteration(bool enabled = true) {
+    SendMessages(enabled);
+
+    basic_simulation_.SendPositionMessage();
+    basic_loop_.Iterate();
+    basic_simulation_.Simulate();
+
+    TickTime();
+  }
+
+  BasicQueue basic_queue_;
+  Basic basic_loop_;
+  BasicSimulation basic_simulation_;
+};
+
+// Tests that when the motor has finished intaking it stops.
+TEST_F(BasicControlLoopTest, IntakeLimitTransitionsToTrue) {
+  ASSERT_TRUE(basic_queue_.goal.MakeWithBuilder().intake(true).Send());
+  basic_simulation_.set_limit_sensor(false);
+
+  RunIteration();
+
+  basic_simulation_.VerifyResults(12.0, false);
+
+  ASSERT_TRUE(basic_queue_.goal.MakeWithBuilder().intake(true).Send());
+  basic_simulation_.set_limit_sensor(true);
+
+  RunIteration();
+
+  basic_simulation_.VerifyResults(0.0, true);
+}
+
+// Tests that the intake goes on if the sensor is not pressed
+// and intake is requested.
+TEST_F(BasicControlLoopTest, IntakeLimitNotSet) {
+  ASSERT_TRUE(basic_queue_.goal.MakeWithBuilder().intake(true).Send());
+  basic_simulation_.set_limit_sensor(false);
+
+  RunIteration();
+
+  basic_simulation_.VerifyResults(12.0, false);
+}
+
+// Tests that the intake is off if no intake is requested,
+// even if the limit sensor is off.
+TEST_F(BasicControlLoopTest, NoIntakeLimitNotSet) {
+  ASSERT_TRUE(basic_queue_.goal.MakeWithBuilder().intake(false).Send());
+  basic_simulation_.set_limit_sensor(false);
+
+  RunIteration();
+
+  basic_simulation_.VerifyResults(0.0, false);
+}
+
+// Tests that the intake is off even if the limit sensor
+// is pressed and intake is requested.
+TEST_F(BasicControlLoopTest, IntakeLimitSet) {
+  ASSERT_TRUE(basic_queue_.goal.MakeWithBuilder().intake(true).Send());
+  basic_simulation_.set_limit_sensor(true);
+
+  RunIteration();
+
+  basic_simulation_.VerifyResults(0.0, true);
+}
+
+// Tests that the intake is off if no intake is requested,
+TEST_F(BasicControlLoopTest, NoIntakeLimitSet) {
+  ASSERT_TRUE(basic_queue_.goal.MakeWithBuilder().intake(false).Send());
+  basic_simulation_.set_limit_sensor(true);
+
+  RunIteration();
+
+  basic_simulation_.VerifyResults(0.0, false);
+}
+
+// Tests that the control loop handles things properly if no goal is set.
+TEST_F(BasicControlLoopTest, NoGoalSet) {
+  basic_simulation_.set_limit_sensor(true);
+
+  RunIteration();
+
+  basic_simulation_.VerifyResults(0.0, false);
+}
+
+// Tests that the control loop handles things properly if disabled.
+TEST_F(BasicControlLoopTest, Disabled) {
+  basic_simulation_.set_limit_sensor(true);
+
+  ASSERT_TRUE(basic_queue_.goal.MakeWithBuilder().intake(true).Send());
+
+  RunIteration(false);
+
+  basic_simulation_.VerifyResults(0.0, false);
+}
+
+}  // namespace testing
+}  // namespace codelab
+}  // namespace frc971