1 files changed, 91 insertions, 0 deletions
diff --git a/test/core/transport/pid_controller_test.cc b/test/core/transport/pid_controller_test.cc
new file mode 100644
index 0000000000..081d03472a
--- /dev/null
+++ b/test/core/transport/pid_controller_test.cc
@@ -0,0 +1,91 @@
+/*
+ *
+ * Copyright 2016 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include "src/core/lib/transport/pid_controller.h"
+
+#include <float.h>
+#include <math.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/useful.h>
+#include <gtest/gtest.h>
+#include "src/core/lib/support/string.h"
+#include "test/core/util/test_config.h"
+
+namespace grpc_core {
+namespace testing {
+
+TEST(PidController, NoOp) {
+  PidController pid(PidController::Args()
+                        .set_gain_p(1)
+                        .set_gain_i(1)
+                        .set_gain_d(1)
+                        .set_initial_control_value(1));
+}
+
+struct SimpleConvergenceTestArgs {
+  double gain_p;
+  double gain_i;
+  double gain_d;
+  double dt;
+  double set_point;
+  double start;
+};
+
+std::ostream& operator<<(std::ostream& out, SimpleConvergenceTestArgs args) {
+  return out << "gain_p:" << args.gain_p << " gain_i:" << args.gain_i
+             << " gain_d:" << args.gain_d << " dt:" << args.dt
+             << " set_point:" << args.set_point << " start:" << args.start;
+}
+
+class SimpleConvergenceTest
+    : public ::testing::TestWithParam<SimpleConvergenceTestArgs> {};
+
+TEST_P(SimpleConvergenceTest, Converges) {
+  PidController pid(PidController::Args()
+                        .set_gain_p(GetParam().gain_p)
+                        .set_gain_i(GetParam().gain_i)
+                        .set_gain_d(GetParam().gain_d)
+                        .set_initial_control_value(GetParam().start));
+
+  for (int i = 0; i < 100000; i++) {
+    pid.Update(GetParam().set_point - pid.last_control_value(), GetParam().dt);
+  }
+
+  EXPECT_LT(fabs(GetParam().set_point - pid.last_control_value()), 0.1);
+  if (GetParam().gain_i > 0) {
+    EXPECT_LT(fabs(pid.error_integral()), 0.1);
+  }
+}
+
+INSTANTIATE_TEST_CASE_P(
+    X, SimpleConvergenceTest,
+    ::testing::Values(SimpleConvergenceTestArgs{0.2, 0, 0, 1, 100, 0},
+                      SimpleConvergenceTestArgs{0.2, 0.1, 0, 1, 100, 0},
+                      SimpleConvergenceTestArgs{0.2, 0.1, 0.1, 1, 100, 0}));
+
+}  // namespace testing
+}  // namespace grpc_core
+
+int main(int argc, char** argv) {
+  grpc_test_init(argc, argv);
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}