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.checks.design;
  
  import static com.google.common.truth.Truth.assertWithMessage;
  import static com.puppycrawl.tools.checkstyle.checks.design.OneTopLevelClassCheck.MSG_KEY;
  
  import java.io.File;
  import java.util.Arrays;
  import java.util.List;
  
  import org.junit.jupiter.api.Test;
  
  import com.google.common.collect.ImmutableMap;
  import com.puppycrawl.tools.checkstyle.AbstractModuleTestSupport;
  import com.puppycrawl.tools.checkstyle.DefaultConfiguration;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  
  public class OneTopLevelClassCheckTest extends AbstractModuleTestSupport {
  
      @Override
      protected String getPackageLocation() {
          return "com/puppycrawl/tools/checkstyle/checks/design/onetoplevelclass";
      }
  
      @Test
      public void testGetRequiredTokens() {
          final OneTopLevelClassCheck checkObj = new OneTopLevelClassCheck();
          final int[] expected = {TokenTypes.COMPILATION_UNIT};
          assertWithMessage("Required tokens are invalid.")
                  .that(checkObj.getRequiredTokens())
                  .isEqualTo(expected);
      }
  
      @Test
      public void testClearState() throws Exception {
          final DefaultConfiguration checkConfig =
                  createModuleConfig(OneTopLevelClassCheck.class);
          final String firstInputFilePath = getPath("InputOneTopLevelClassDeclarationOrder.java");
          final String secondInputFilePath = getPath("InputOneTopLevelClassInterface2.java");
  
          final File[] inputs = {
              new File(firstInputFilePath),
              new File(secondInputFilePath),
          };
  
          final List<String> expectedFirstInput = Arrays.asList(
              "16:1: " + getCheckMessage(MSG_KEY, "InputDeclarationOrderEnum"),
              "26:1: " + getCheckMessage(MSG_KEY, "InputDeclarationOrderAnnotation"));
          final List<String> expectedSecondInput = Arrays.asList(
              "9:1: " + getCheckMessage(MSG_KEY, "InputOneTopLevelClassInterface2inner1"),
              "17:1: " + getCheckMessage(MSG_KEY, "InputOneTopLevelClassInterface2inner2"));
  
          verify(createChecker(checkConfig), inputs,
              ImmutableMap.of(firstInputFilePath, expectedFirstInput,
                  secondInputFilePath, expectedSecondInput));
      }
  
      @Test
      public void testAcceptableTokens() {
          final OneTopLevelClassCheck check = new OneTopLevelClassCheck();
          final int[] expected = {TokenTypes.COMPILATION_UNIT};
          assertWithMessage("Default required tokens are invalid")
              .that(check.getAcceptableTokens())
              .isEqualTo(expected);
      }
  
      @Test
      public void testFileWithOneTopLevelClass() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClass.java"), expected);
      }
  
      @Test
      public void testFileWithOneTopLevelInterface() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClassInterface.java"), expected);
      }
  
      @Test
      public void testFileWithOneTopLevelEnum() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClassEnum.java"), expected);
      }
  
      @Test
      public void testFileWithOneTopLevelAnnotation() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClassAnnotation.java"), expected);
      }
  
      @Test
      public void testFileWithNoPublicTopLevelClass() throws Exception {
          final String[] expected = {
              "14:1: " + getCheckMessage(MSG_KEY, "InputOneTopLevelClassNoPublic2"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClassNoPublic.java"), expected);
      }
  
      @Test
      public void testFileWithThreeTopLevelInterface() throws Exception {
          final String[] expected = {
              "9:1: " + getCheckMessage(MSG_KEY, "InputOneTopLevelClassInterface3inner1"),
              "17:1: " + getCheckMessage(MSG_KEY, "InputOneTopLevelClassInterface3inner2"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClassInterface3.java"), expected);
      }
  
      @Test
      public void testFileWithThreeTopLevelEnum() throws Exception {
          final String[] expected = {
              "9:1: " + getCheckMessage(MSG_KEY, "InputOneTopLevelClassEnum2inner1"),
              "17:1: " + getCheckMessage(MSG_KEY, "InputOneTopLevelClassEnum2inner2"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClassEnum2.java"), expected);
      }
  
      @Test
      public void testFileWithThreeTopLevelAnnotation() throws Exception {
          final String[] expected = {
              "15:1: " + getCheckMessage(MSG_KEY, "InputOneTopLevelClassAnnotation2A"),
              "20:1: " + getCheckMessage(MSG_KEY, "InputOneTopLevelClassAnnotation2B"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClassAnnotation2.java"), expected);
      }
  
      @Test
      public void testFileWithFewTopLevelClasses() throws Exception {
          final String[] expected = {
              "31:1: " + getCheckMessage(MSG_KEY, "NoSuperClone"),
              "35:1: " + getCheckMessage(MSG_KEY, "InnerClone"),
              "39:1: " + getCheckMessage(MSG_KEY, "CloneWithTypeArguments"),
              "43:1: " + getCheckMessage(MSG_KEY, "CloneWithTypeArgumentsAndNoSuper"),
              "47:1: " + getCheckMessage(MSG_KEY, "MyClassWithGenericSuperMethod"),
              "51:1: " + getCheckMessage(MSG_KEY, "AnotherClass"),
              "54:1: " + getCheckMessage(MSG_KEY, "NativeTest"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClassClone.java"), expected);
      }
  
      @Test
      public void testFileWithSecondEnumTopLevelClass() throws Exception {
          final String[] expected = {
              "16:1: " + getCheckMessage(MSG_KEY, "InputDeclarationOrderEnum2"),
              "26:1: " + getCheckMessage(MSG_KEY, "InputDeclarationOrderAnnotation2"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClassDeclarationOrder2.java"), expected);
      }
  
      @Test
      public void testPackageInfoWithNoTypesDeclared() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getNonCompilablePath("package-info.java"), expected);
      }
  
      @Test
      public void testFileWithMultipleSameLine() throws Exception {
          final String[] expected = {
              "9:47: " + getCheckMessage(MSG_KEY, "ViolatingSecondType"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClassSameLine.java"), expected);
      }
  
      @Test
      public void testFileWithIndentation() throws Exception {
          final String[] expected = {
              "13:2: " + getCheckMessage(MSG_KEY, "ViolatingIndentedClass1"),
              "17:5: " + getCheckMessage(MSG_KEY, "ViolatingIndentedClass2"),
              "21:1: " + getCheckMessage(MSG_KEY, "ViolatingNonIndentedInterface"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputOneTopLevelClassIndentation.java"), expected);
      }
  
      @Test
      public void testOneTopLevelClassRecords() throws Exception {
          final String[] expected = {
              "13:1: " + getCheckMessage(MSG_KEY, "TestRecord1"),
              "17:1: " + getCheckMessage(MSG_KEY, "TestRecord2"),
          };
          verifyWithInlineConfigParser(
                  getNonCompilablePath("InputOneTopLevelClassRecords.java"), expected);
      }
  
      @Test
      public void testOneTopLevelClassEmpty() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getNonCompilablePath("InputOneTopLevelClassEmpty.java"), expected);
      }
  }
  