code: ///////////////////////////////////////////////////////////////////////////////////////////////
  // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
  // Copyright (C) 2001-2023 the original author or authors.
  //
  // This library is free software; you can redistribute it and/or
  // modify it under the terms of the GNU Lesser General Public
  // License as published by the Free Software Foundation; either
  // version 2.1 of the License, or (at your option) any later version.
  //
  // This library is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  // Lesser General Public License for more details.
  //
  // You should have received a copy of the GNU Lesser General Public
  // License along with this library; if not, write to the Free Software
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  ///////////////////////////////////////////////////////////////////////////////////////////////
  
  package com.puppycrawl.tools.checkstyle.gui;
  
  import static com.google.common.truth.Truth.assertWithMessage;
  
  import java.awt.Window;
  import java.util.Arrays;
  
  import javax.swing.SwingUtilities;
  
  import org.junit.jupiter.params.ParameterizedTest;
  import org.junit.jupiter.params.provider.ValueSource;
  
  import com.puppycrawl.tools.checkstyle.AbstractGuiTestSupport;
  
  public class MainTest extends AbstractGuiTestSupport {
  
      @Override
      protected String getPackageLocation() {
          return "com/puppycrawl/tools/checkstyle/gui/main";
      }
  
      /**
       * Parametrized test to invoke Checkstyle GUI with different command line arguments.
       *
       * @param argList the command line arguments delimited by a semicolon (";")
       * @throws Exception if an exception occurs while executing the test.
       */
      @ParameterizedTest
      @ValueSource(strings = {";", "InputMain.java"})
      public void testMain(String argList) throws Exception {
          final String[] args = argList.split(";");
          for (int i = 0; i < args.length; i++) {
              args[i] = getPath(args[i]);
          }
  
          // Create the main window
          Main.main(args);
  
          SwingUtilities.invokeAndWait(() -> {
              // Close the main window
              final long mainFrameCount = Arrays.stream(Window.getWindows())
                      .filter(wnd -> wnd instanceof MainFrame && wnd.isVisible())
                      .peek(Window::dispose)
                      .count();
              assertWithMessage("Only one window is expected")
                      .that(mainFrameCount)
                      .isEqualTo(1);
          });
      }
  
  }
  