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.google.checkstyle.test.chapter3filestructure.rule341onetoplevel;
  
  import org.junit.jupiter.api.Test;
  
  import com.google.checkstyle.test.base.AbstractGoogleModuleTestSupport;
  import com.puppycrawl.tools.checkstyle.api.Configuration;
  import com.puppycrawl.tools.checkstyle.checks.design.OneTopLevelClassCheck;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  
  public class OneTopLevelClassTest extends AbstractGoogleModuleTestSupport {
  
      @Override
      protected String getPackageLocation() {
          return "com/google/checkstyle/test/chapter3filestructure/rule341onetoplevel";
      }
  
      @Test
      public void testBad() throws Exception {
          final Class<OneTopLevelClassCheck> clazz = OneTopLevelClassCheck.class;
          final String messageKey = "one.top.level.class";
  
          final String[] expected = {
              "25:1: " + getCheckMessage(clazz, messageKey, "NoSuperClone"),
              "33:1: " + getCheckMessage(clazz, messageKey, "InnerClone"),
              "50:1: " + getCheckMessage(clazz, messageKey, "CloneWithTypeArguments"),
              "55:1: " + getCheckMessage(clazz, messageKey, "CloneWithTypeArgumentsAndNoSuper"),
              "60:1: " + getCheckMessage(clazz, messageKey, "MyClassWithGenericSuperMethod"),
              "77:1: " + getCheckMessage(clazz, messageKey, "AnotherClass"),
          };
  
          final Configuration checkConfig = getModuleConfig("OneTopLevelClass");
          final String filePath = getPath("InputOneTopLevelClassBasic.java");
  
          final Integer[] warnList = getLinesWithWarn(filePath);
          verify(checkConfig, filePath, expected, warnList);
      }
  
      @Test
      public void testGood() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
  
          final Configuration checkConfig = getModuleConfig("OneTopLevelClass");
          final String filePath = getPath("InputOneTopLevelClassGood.java");
  
          final Integer[] warnList = getLinesWithWarn(filePath);
          verify(checkConfig, filePath, expected, warnList);
      }
  
      @Test
      public void testBad1() throws Exception {
          final Class<OneTopLevelClassCheck> clazz = OneTopLevelClassCheck.class;
          final String messageKey = "one.top.level.class";
  
          final String[] expected = {
              "4:1: " + getCheckMessage(clazz, messageKey, "FooEnum"),
              "5:1: " + getCheckMessage(clazz, messageKey, "FooAt"),
          };
  
          final Configuration checkConfig = getModuleConfig("OneTopLevelClass");
          final String filePath = getPath("InputOneTopLevelClassBad1.java");
  
          final Integer[] warnList = getLinesWithWarn(filePath);
          verify(checkConfig, filePath, expected, warnList);
      }
  
      @Test
      public void testBad2() throws Exception {
          final Class<OneTopLevelClassCheck> clazz = OneTopLevelClassCheck.class;
          final String messageKey = "one.top.level.class";
  
          final String[] expected = {
              "5:1: " + getCheckMessage(clazz, messageKey, "FooIn"),
              "7:1: " + getCheckMessage(clazz, messageKey, "FooClass"),
          };
  
          final Configuration checkConfig = getModuleConfig("OneTopLevelClass");
          final String filePath = getPath("InputOneTopLevelClassBad2.java");
  
          final Integer[] warnList = getLinesWithWarn(filePath);
          verify(checkConfig, filePath, expected, warnList);
      }
  
  }
  