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.sizes;
  
  import static com.google.common.truth.Truth.assertWithMessage;
  import static com.puppycrawl.tools.checkstyle.checks.sizes.OuterTypeNumberCheck.MSG_KEY;
  
  import java.io.File;
  import java.util.Optional;
  
  import org.junit.jupiter.api.Test;
  
  import com.puppycrawl.tools.checkstyle.AbstractModuleTestSupport;
  import com.puppycrawl.tools.checkstyle.JavaParser;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.internal.utils.TestUtil;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  
  public class OuterTypeNumberCheckTest extends AbstractModuleTestSupport {
  
      @Override
      protected String getPackageLocation() {
          return "com/puppycrawl/tools/checkstyle/checks/sizes/outertypenumber";
      }
  
      @Test
      public void testGetRequiredTokens() {
          final OuterTypeNumberCheck checkObj = new OuterTypeNumberCheck();
          final int[] expected = {
              TokenTypes.CLASS_DEF,
              TokenTypes.INTERFACE_DEF,
              TokenTypes.ENUM_DEF,
              TokenTypes.ANNOTATION_DEF,
              TokenTypes.RECORD_DEF,
          };
          assertWithMessage("Default required tokens are invalid")
              .that(checkObj.getRequiredTokens())
              .isEqualTo(expected);
      }
  
      @Test
      public void testGetAcceptableTokens() {
          final OuterTypeNumberCheck outerTypeNumberObj =
              new OuterTypeNumberCheck();
          final int[] actual = outerTypeNumberObj.getAcceptableTokens();
          final int[] expected = {
              TokenTypes.CLASS_DEF,
              TokenTypes.INTERFACE_DEF,
              TokenTypes.ENUM_DEF,
              TokenTypes.ANNOTATION_DEF,
              TokenTypes.RECORD_DEF,
          };
  
          assertWithMessage("Default acceptable tokens are invalid")
              .that(actual)
              .isEqualTo(expected);
      }
  
      @Test
      public void testDefault() throws Exception {
          final String[] expected = {
              "8:1: " + getCheckMessage(MSG_KEY, 3, 1),
          };
          verifyWithInlineConfigParser(
                  getPath("InputOuterTypeNumberSimple.java"), expected);
      }
  
      @Test
      public void testMax30() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputOuterTypeNumberSimple1.java"), expected);
      }
  
      @Test
      public void testWithInnerClass() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputOuterTypeNumberEmptyInner.java"), expected);
      }
  
      @Test
      public void testWithRecords() throws Exception {
  
          final int max = 1;
  
          final String[] expected = {
              "9:1: " + getCheckMessage(MSG_KEY, 2, max),
          };
  
          verifyWithInlineConfigParser(
                  getNonCompilablePath("InputOuterTypeNumberRecords.java"), expected);
      }
  
      /**
       * Checks if the private field {@code currentDepth} and {@code outerNum} is
       * properly cleared during the start of processing the next file in the
       * check as they are file specific values.
       *
       * @throws Exception if there is an error.
       */
      @Test
      public void testClearState() throws Exception {
          final OuterTypeNumberCheck check = new OuterTypeNumberCheck();
          final DetailAST root = JavaParser.parseFile(
                  new File(getPath("InputOuterTypeNumberSimple.java")),
                  JavaParser.Options.WITHOUT_COMMENTS);
          final Optional<DetailAST> classDef = TestUtil.findTokenInAstByPredicate(root,
              ast -> ast.getType() == TokenTypes.CLASS_DEF);
  
          assertWithMessage("Ast should contain CLASS_DEF")
                  .that(classDef.isPresent())
                  .isTrue();
          assertWithMessage("State is not cleared on beginTree")
                  .that(
                      TestUtil.isStatefulFieldClearedDuringBeginTree(check, classDef.get(),
                              "currentDepth",
                              currentDepth -> ((Number) currentDepth).intValue() == 0))
                  .isTrue();
          assertWithMessage("State is not cleared on beginTree")
                  .that(
                      TestUtil.isStatefulFieldClearedDuringBeginTree(check, classDef.get(),
                              "outerNum",
                              outerNum -> ((Number) outerNum).intValue() == 0))
                  .isTrue();
      }
  
  }
  