Use namespaces (#328)

* add expand_topic_or_service_name()

* use namespace in intra process

(actual change to topic names in next commit)

* catch and report name issues

for node names, namespaces, and topic/service names

* address comment

rclcpp/test/test_client.cpp

@@ -0,0 +1,60 @@
+// Copyright 2017 Open Source Robotics Foundation, Inc.
+//
+// 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 <gtest/gtest.h>
+
+#include <string>
+#include <memory>
+
+#include "rclcpp/exceptions.hpp"
+#include "rclcpp/rclcpp.hpp"
+
+#include "rcl_interfaces/srv/list_parameters.hpp"
+
+class TestClient : public ::testing::Test
+{
+protected:
+  static void SetUpTestCase()
+  {
+    rclcpp::init(0, nullptr);
+  }
+
+  void SetUp()
+  {
+    node = std::make_shared<rclcpp::node::Node>("my_node", "/ns");
+  }
+
+  void TearDown()
+  {
+    node.reset();
+  }
+
+  rclcpp::node::Node::SharedPtr node;
+};
+
+/*
+   Testing client construction and destruction.
+ */
+TEST_F(TestClient, construction_and_destruction) {
+  using rcl_interfaces::srv::ListParameters;
+  {
+    auto client = node->create_client<ListParameters>("service");
+  }
+
+  {
+    ASSERT_THROW({
+      auto client = node->create_client<ListParameters>("invalid_service?");
+    }, rclcpp::exceptions::InvalidServiceNameError);
+  }
+}