Added unit test for Plufin base class

rqt_gui_cpp/CMakeLists.txt

@@ -66,6 +66,16 @@ target_link_libraries(${PROJECT_NAME} PRIVATE
 if(BUILD_TESTING)
   find_package(ament_lint_auto REQUIRED)
   ament_lint_auto_find_test_dependencies()
+
+  find_package(ament_cmake_gtest REQUIRED)
+  ament_add_gtest(test_plugin test/test_plugin.cpp)
+  if(TARGET test_plugin)
+    target_link_libraries(test_plugin
+      ${PROJECT_NAME}
+      rclcpp::rclcpp
+      Qt${QT_VERSION_MAJOR}::Widgets
+    )
+  endif()
 endif()
 
 install(

rqt_gui_cpp/package.xml

@@ -23,6 +23,7 @@
   <build_depend>qt-base-dev</build_depend>
   <exec_depend version_gte="0.3.0">qt_gui_cpp</exec_depend>
 
+  <test_depend>ament_cmake_gtest</test_depend>
   <test_depend>ament_lint_auto</test_depend>
   <test_depend>ament_lint_common</test_depend>
 

rqt_gui_cpp/test/test_plugin.cpp

@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2026, Open Source Robotics Foundation, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * Redistributions in binary form must reproduce the above
+ *     copyright notice, this list of conditions and the following
+ *     disclaimer in the documentation and/or other materials provided
+ *     with the distribution.
+ *   * Neither the name of the TU Darmstadt nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <gtest/gtest.h>
+
+#include <memory>
+
+#include <rclcpp/rclcpp.hpp>
+#include <rqt_gui_cpp/plugin.hpp>
+
+namespace
+{
+
+// Minimal concrete plugin used to exercise the rqt_gui_cpp::Plugin base class.
+// It exposes the protected node_ member so the test can verify passInNode().
+class TestPlugin
+  : public rqt_gui_cpp::Plugin
+{
+public:
+  rclcpp::Node::SharedPtr node() const
+  {
+    return node_;
+  }
+};
+
+}  // namespace
+
+class PluginTest
+  : public ::testing::Test
+{
+protected:
+  void SetUp() override
+  {
+    rclcpp::init(0, nullptr);
+  }
+
+  void TearDown() override
+  {
+    rclcpp::shutdown();
+  }
+};
+
+TEST_F(PluginTest, node_is_null_before_pass_in_node)
+{
+  TestPlugin plugin;
+  EXPECT_EQ(plugin.node(), nullptr);
+}
+
+TEST_F(PluginTest, pass_in_node_stores_the_node)
+{
+  TestPlugin plugin;
+  auto node = std::make_shared<rclcpp::Node>("test_rqt_gui_cpp_plugin");
+
+  plugin.passInNode(node);
+
+  EXPECT_EQ(plugin.node(), node);
+}
+
+TEST_F(PluginTest, shutdown_plugin_is_safe_to_call)
+{
+  TestPlugin plugin;
+  EXPECT_NO_THROW(plugin.shutdownPlugin());
+}