From ea3a4033520484d01caec30ebef3142b96f2efbc Mon Sep 17 00:00:00 2001
From: Eric Cousineau <eric.cousineau@tri.global>
Date: Tue, 20 Feb 2018 10:56:18 -0500
Subject: [PATCH] framework_py: Add test of using AbstractValue's in input
 ports (following up from pybind unique_ptr snafu)

---
 bindings/pydrake/systems/framework_py.cc      | 26 ++++++++++++--
 bindings/pydrake/systems/primitives_py.cc     |  5 +++
 bindings/pydrake/systems/test/general_test.py | 35 +++++++++++++++++++
 3 files changed, 63 insertions(+), 3 deletions(-)

diff --git a/bindings/pydrake/systems/framework_py.cc b/bindings/pydrake/systems/framework_py.cc
index 34a1028b4af3..e3ff65cd823b 100644
--- a/bindings/pydrake/systems/framework_py.cc
+++ b/bindings/pydrake/systems/framework_py.cc
@@ -283,7 +283,16 @@ PYBIND11_MODULE(framework, m) {
         "EvalVectorInput",
         [](const System<T>* self, const Context<T>& arg1, int arg2) {
           return self->EvalVectorInput(arg1, arg2);
-        }, py_reference_internal)
+        }, py_reference,
+        // Keep alive, ownership: `return` keeps `Context` alive.
+        py::keep_alive<0, 2>())
+    .def(
+        "EvalAbstractInput",
+        [](const System<T>* self, const Context<T>& arg1, int arg2) {
+          return self->EvalAbstractInput(arg1, arg2);
+        }, py_reference,
+        // Keep alive, ownership: `return` keeps `Context` alive.
+        py::keep_alive<0, 2>())
     .def("CalcOutput", &System<T>::CalcOutput)
     // Sugar.
     .def(
@@ -352,9 +361,16 @@ PYBIND11_MODULE(framework, m) {
     .def("get_num_input_ports", &Context<T>::get_num_input_ports)
     .def("FixInputPort",
          py::overload_cast<int, unique_ptr<BasicVector<T>>>(
-             &Context<T>::FixInputPort), py_reference_internal,
+             &Context<T>::FixInputPort),
+         py_reference_internal,
          // Keep alive, ownership: `BasicVector` keeps `self` alive.
          py::keep_alive<3, 1>())
+    .def("FixInputPort",
+         py::overload_cast<int, unique_ptr<AbstractValue>>(
+             &Context<T>::FixInputPort),
+         py_reference_internal,
+         // Keep alive, ownership: `AbstractValue` keeps `self` alive.
+         py::keep_alive<3, 1>())
     .def("get_time", &Context<T>::get_time)
     .def("set_time", &Context<T>::set_time)
     .def("Clone", &Context<T>::Clone)
@@ -437,8 +453,12 @@ PYBIND11_MODULE(framework, m) {
   py::class_<OutputPort<T>>(m, "OutputPort")
     .def("size", &OutputPort<T>::size);
 
-  py::class_<SystemOutput<T>>(m, "SystemOutput")
+  py::class_<SystemOutput<T>> system_output(m, "SystemOutput");
+  DefClone(&system_output);
+  system_output
     .def("get_num_ports", &SystemOutput<T>::get_num_ports)
+    .def("get_data", &SystemOutput<T>::get_data,
+         py_reference_internal)
     .def("get_vector_data", &SystemOutput<T>::get_vector_data,
          py_reference_internal);
 
diff --git a/bindings/pydrake/systems/primitives_py.cc b/bindings/pydrake/systems/primitives_py.cc
index f39e73d81073..e21611166781 100644
--- a/bindings/pydrake/systems/primitives_py.cc
+++ b/bindings/pydrake/systems/primitives_py.cc
@@ -9,6 +9,7 @@
 #include "drake/systems/primitives/constant_vector_source.h"
 #include "drake/systems/primitives/integrator.h"
 #include "drake/systems/primitives/linear_system.h"
+#include "drake/systems/primitives/pass_through.h"
 #include "drake/systems/primitives/signal_logger.h"
 #include "drake/systems/primitives/zero_order_hold.h"
 
@@ -72,6 +73,10 @@ PYBIND11_MODULE(primitives, m) {
            py::arg("A"), py::arg("B"), py::arg("C"), py::arg("D"),
            py::arg("time_period") = 0.0);
 
+  py::class_<PassThrough<T>, LeafSystem<T>>(m, "PassThrough")
+    .def(py::init<int>())
+    .def(py::init<const AbstractValue&>());
+
   py::class_<SignalLogger<T>, LeafSystem<T>>(m, "SignalLogger")
       .def(py::init<int>())
       .def(py::init<int, int>())
diff --git a/bindings/pydrake/systems/test/general_test.py b/bindings/pydrake/systems/test/general_test.py
index 5835d606d855..e57ca1a3e625 100644
--- a/bindings/pydrake/systems/test/general_test.py
+++ b/bindings/pydrake/systems/test/general_test.py
@@ -12,9 +12,11 @@
     Simulator,
     )
 from pydrake.systems.framework import (
+    AbstractValue,
     BasicVector,
     Diagram,
     DiagramBuilder,
+    VectorBase,
     )
 from pydrake.systems.primitives import (
     Adder,
@@ -22,10 +24,19 @@
     ConstantVectorSource,
     Integrator,
     LinearSystem,
+    PassThrough,
     SignalLogger,
     )
 
 
+def compare_value(test, a, b):
+    if isinstance(a, VectorBase):
+        test.assertTrue(np.allclose(a.get_value(), b.get_value()))
+    else:
+        test.assertEquals(type(a.get_value()), type(b.get_value()))
+        test.assertEquals(a.get_value(), b.get_value())
+
+
 class TestGeneral(unittest.TestCase):
     def test_simulator_ctor(self):
         # Create simple system.
@@ -203,6 +214,30 @@ def test_linear_affine_system(self):
         self.assertEqual(system.y0(), y0)
         self.assertEqual(system.time_period(), .1)
 
+    def test_vector_pass_through(self):
+        model_value = BasicVector([1., 2, 3])
+        system = PassThrough(model_value.size())
+        context = system.CreateDefaultContext()
+        context.FixInputPort(0, model_value)
+        output = system.AllocateOutput(context)
+        input_eval = system.EvalVectorInput(context, 0)
+        compare_value(self, input_eval, model_value)
+        system.CalcOutput(context, output)
+        output_value = output.get_vector_data(0)
+        compare_value(self, output_value, model_value)
+
+    def test_abstract_pass_through(self):
+        model_value = AbstractValue.Make("Hello world")
+        system = PassThrough(model_value)
+        context = system.CreateDefaultContext()
+        context.FixInputPort(0, model_value)
+        output = system.AllocateOutput(context)
+        input_eval = system.EvalAbstractInput(context, 0)
+        compare_value(self, input_eval, model_value)
+        system.CalcOutput(context, output)
+        output_value = output.get_data(0)
+        compare_value(self, output_value, model_value)
+
 
 if __name__ == '__main__':
     unittest.main()