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.coding;
  
  import static com.google.common.truth.Truth.assertWithMessage;
  import static com.puppycrawl.tools.checkstyle.checks.coding.ReturnCountCheck.MSG_KEY;
  import static com.puppycrawl.tools.checkstyle.checks.coding.ReturnCountCheck.MSG_KEY_VOID;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  
  import java.io.File;
  import java.util.Collection;
  import java.util.Optional;
  import java.util.Set;
  
  import org.junit.jupiter.api.Test;
  
  import com.puppycrawl.tools.checkstyle.AbstractModuleTestSupport;
  import com.puppycrawl.tools.checkstyle.DetailAstImpl;
  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 ReturnCountCheckTest extends AbstractModuleTestSupport {
  
      @Override
      protected String getPackageLocation() {
          return "com/puppycrawl/tools/checkstyle/checks/coding/returncount";
      }
  
      @Test
      public void testDefault() throws Exception {
          final String[] expected = {
              "28:5: " + getCheckMessage(MSG_KEY_VOID, 7, 1),
              "40:5: " + getCheckMessage(MSG_KEY_VOID, 2, 1),
              "45:17: " + getCheckMessage(MSG_KEY_VOID, 6, 1),
              "59:5: " + getCheckMessage(MSG_KEY, 7, 2),
          };
          verifyWithInlineConfigParser(
                  getPath("InputReturnCountSwitches.java"), expected);
      }
  
      @Test
      public void testFormat() throws Exception {
          final String[] expected = {
              "15:5: " + getCheckMessage(MSG_KEY, 7, 2),
              "28:5: " + getCheckMessage(MSG_KEY_VOID, 7, 1),
              "40:5: " + getCheckMessage(MSG_KEY_VOID, 2, 1),
              "45:17: " + getCheckMessage(MSG_KEY_VOID, 6, 1),
              "59:5: " + getCheckMessage(MSG_KEY, 7, 2),
          };
          verifyWithInlineConfigParser(
                  getPath("InputReturnCountSwitches2.java"), expected);
      }
  
      @Test
      public void testMethodsAndLambdas() throws Exception {
          final String[] expected = {
              "25:55: " + getCheckMessage(MSG_KEY, 2, 1),
              "37:49: " + getCheckMessage(MSG_KEY, 2, 1),
              "44:42: " + getCheckMessage(MSG_KEY, 3, 1),
              "51:5: " + getCheckMessage(MSG_KEY, 2, 1),
              "59:57: " + getCheckMessage(MSG_KEY, 2, 1),
          };
          verifyWithInlineConfigParser(
                  getPath("InputReturnCountLambda.java"), expected);
      }
  
      @Test
      public void testLambdasOnly() throws Exception {
          final String[] expected = {
              "43:42: " + getCheckMessage(MSG_KEY, 3, 2),
          };
          verifyWithInlineConfigParser(
                  getPath("InputReturnCountLambda2.java"), expected);
      }
  
      @Test
      public void testMethodsOnly() throws Exception {
          final String[] expected = {
              "35:5: " + getCheckMessage(MSG_KEY, 3, 2),
              "42:5: " + getCheckMessage(MSG_KEY, 4, 2),
              "50:5: " + getCheckMessage(MSG_KEY, 4, 2),
              "65:5: " + getCheckMessage(MSG_KEY, 3, 2),
          };
          verifyWithInlineConfigParser(
                  getPath("InputReturnCountLambda3.java"), expected);
      }
  
      @Test
      public void testWithReturnOnlyAsTokens() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputReturnCountLambda4.java"), expected);
      }
  
      @Test
      public void testImproperToken() {
          final ReturnCountCheck check = new ReturnCountCheck();
  
          final DetailAstImpl classDefAst = new DetailAstImpl();
          classDefAst.setType(TokenTypes.CLASS_DEF);
  
          try {
              check.visitToken(classDefAst);
              assertWithMessage("IllegalStateException is expected").fail();
          }
          catch (IllegalStateException ex) {
              // it is OK
          }
  
          try {
              check.leaveToken(classDefAst);
              assertWithMessage("IllegalStateException is expected").fail();
          }
          catch (IllegalStateException ex) {
              // it is OK
          }
      }
  
      @Test
      public void testMaxForVoid() throws Exception {
          final String[] expected = {
              "14:5: " + getCheckMessage(MSG_KEY_VOID, 1, 0),
              "18:5: " + getCheckMessage(MSG_KEY_VOID, 1, 0),
              "24:5: " + getCheckMessage(MSG_KEY_VOID, 2, 0),
              "40:5: " + getCheckMessage(MSG_KEY, 3, 2),
              "51:5: " + getCheckMessage(MSG_KEY_VOID, 2, 0),
          };
          verifyWithInlineConfigParser(
                  getPath("InputReturnCountVoid.java"), expected);
      }
  
      /**
       * We cannot reproduce situation when visitToken is called and leaveToken is not.
       * So, we have to use reflection to be sure that even in such situation
       * state of the field will be cleared.
       *
       * @throws Exception when code tested throws exception
       */
      @Test
      @SuppressWarnings("unchecked")
      public void testClearState() throws Exception {
          final ReturnCountCheck check = new ReturnCountCheck();
          final Optional<DetailAST> methodDef = TestUtil.findTokenInAstByPredicate(
              JavaParser.parseFile(new File(getPath("InputReturnCountVoid.java")),
                  JavaParser.Options.WITHOUT_COMMENTS),
              ast -> ast.getType() == TokenTypes.METHOD_DEF);
  
          assertWithMessage("Ast should contain METHOD_DEF")
                  .that(methodDef.isPresent())
                  .isTrue();
          assertWithMessage("State is not cleared on beginTree")
                  .that(TestUtil.isStatefulFieldClearedDuringBeginTree(check, methodDef.get(),
                          "contextStack",
                          contextStack -> ((Collection<Set<String>>) contextStack).isEmpty()))
                  .isTrue();
      }
  
      /**
       * Tries to reproduce system failure to call Check on not acceptable token.
       * It can not be reproduced by Input files. Maintainers thinks that keeping
       * exception on unknown token is beneficial.
       *
       */
      @Test
      public void testImproperVisitToken() {
          final ReturnCountCheck check = new ReturnCountCheck();
          final DetailAstImpl classDefAst = new DetailAstImpl();
          classDefAst.setType(TokenTypes.CLASS_DEF);
          final IllegalStateException exception = assertThrows(IllegalStateException.class,
                  () -> check.visitToken(classDefAst), "IllegalStateException was expected");
  
          assertWithMessage("Message doesn't contain ast")
                  .that(exception.getMessage())
                  .isEqualTo(classDefAst.toString());
      }
  
      /**
       * Tries to reproduce system failure to call Check on not acceptable token.
       * It can not be reproduced by Input files. Maintainers thinks that keeping
       * exception on unknown token is beneficial.
       *
       */
      @Test
      public void testImproperLeaveToken() {
          final ReturnCountCheck check = new ReturnCountCheck();
          final DetailAstImpl classDefAst = new DetailAstImpl();
          classDefAst.setType(TokenTypes.CLASS_DEF);
          final IllegalStateException exception = assertThrows(IllegalStateException.class,
                  () -> check.leaveToken(classDefAst), "IllegalStateException was expected");
  
          assertWithMessage("Message doesn't contain ast")
                  .that(exception.getMessage())
                  .isEqualTo(classDefAst.toString());
      }
  
  }
  