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.metrics;
  
  import static com.google.common.truth.Truth.assertWithMessage;
  import static com.puppycrawl.tools.checkstyle.checks.metrics.NPathComplexityCheck.MSG_KEY;
  
  import java.io.File;
  import java.math.BigInteger;
  import java.util.Collection;
  import java.util.Optional;
  import java.util.SortedSet;
  
  import org.antlr.v4.runtime.CommonToken;
  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.Context;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.api.Violation;
  import com.puppycrawl.tools.checkstyle.internal.utils.TestUtil;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  
  // -@cs[AbbreviationAsWordInName] Can't change check name
  public class NPathComplexityCheckTest extends AbstractModuleTestSupport {
  
      @Override
      protected String getPackageLocation() {
          return "com/puppycrawl/tools/checkstyle/checks/metrics/npathcomplexity";
      }
  
      @Test
      public void testCalculation() throws Exception {
          final String[] expected = {
              "12:5: " + getCheckMessage(MSG_KEY, 2, 0),
              "17:17: " + getCheckMessage(MSG_KEY, 2, 0),
              "29:5: " + getCheckMessage(MSG_KEY, 10, 0),
              "42:5: " + getCheckMessage(MSG_KEY, 3, 0),
              "52:5: " + getCheckMessage(MSG_KEY, 7, 0),
              "70:5: " + getCheckMessage(MSG_KEY, 3, 0),
              "83:5: " + getCheckMessage(MSG_KEY, 3, 0),
              "95:5: " + getCheckMessage(MSG_KEY, 3, 0),
              "111:13: " + getCheckMessage(MSG_KEY, 2, 0),
              "120:5: " + getCheckMessage(MSG_KEY, 48, 0),
              "130:5: " + getCheckMessage(MSG_KEY, 1, 0),
              "131:5: " + getCheckMessage(MSG_KEY, 1, 0),
              "137:17: " + getCheckMessage(MSG_KEY, 3, 0),
              "151:21: " + getCheckMessage(MSG_KEY, 3, 0),
          };
  
          verifyWithInlineConfigParser(
                  getPath("InputNPathComplexityDefault.java"), expected);
      }
  
      @Test
      public void testCalculation2() throws Exception {
          final String[] expected = {
              "12:5: " + getCheckMessage(MSG_KEY, 5, 0),
              "18:5: " + getCheckMessage(MSG_KEY, 5, 0),
              "25:5: " + getCheckMessage(MSG_KEY, 4, 0),
              "40:5: " + getCheckMessage(MSG_KEY, 4, 0),
              "56:5: " + getCheckMessage(MSG_KEY, 6, 0),
              "72:5: " + getCheckMessage(MSG_KEY, 15, 0),
              "97:5: " + getCheckMessage(MSG_KEY, 11, 0),
              "107:5: " + getCheckMessage(MSG_KEY, 8, 0),
              "120:5: " + getCheckMessage(MSG_KEY, 120, 0),
              "132:5: " + getCheckMessage(MSG_KEY, 6, 0),
              "142:5: " + getCheckMessage(MSG_KEY, 21, 0),
              "155:5: " + getCheckMessage(MSG_KEY, 35, 0),
              "163:5: " + getCheckMessage(MSG_KEY, 25, 0),
              "178:5: " + getCheckMessage(MSG_KEY, 2, 0),
          };
  
          verifyWithInlineConfigParser(
                  getPath("InputNPathComplexity.java"), expected);
      }
  
      @Test
      public void testCalculation3() throws Exception {
          final String[] expected = {
              "11:5: " + getCheckMessage(MSG_KEY, 64, 0),
          };
  
          verifyWithInlineConfigParser(
                  getNonCompilablePath("InputNPathComplexityDefault2.java"), expected);
      }
  
      @Test
      public void testIntegerOverflow() throws Exception {
  
          final long largerThanMaxInt = 3_486_784_401L;
  
          final String[] expected = {
              "20:5: " + getCheckMessage(MSG_KEY, largerThanMaxInt, 0),
          };
  
          verifyWithInlineConfigParser(
                  getPath("InputNPathComplexityOverflow.java"), expected);
      }
  
      @Test
      @SuppressWarnings("unchecked")
      public void testStatefulFieldsClearedOnBeginTree1() {
          final DetailAstImpl ast = new DetailAstImpl();
          ast.setType(TokenTypes.LITERAL_ELSE);
  
          final NPathComplexityCheck check = new NPathComplexityCheck();
          assertWithMessage("Stateful field is not cleared after beginTree")
                  .that(TestUtil.isStatefulFieldClearedDuringBeginTree(check, ast, "rangeValues",
                          rangeValues -> ((Collection<Context>) rangeValues).isEmpty()))
                  .isTrue();
          assertWithMessage("Stateful field is not cleared after beginTree")
                  .that(TestUtil.isStatefulFieldClearedDuringBeginTree(check, ast, "expressionValues",
                          expressionValues -> ((Collection<Context>) expressionValues).isEmpty()))
                  .isTrue();
          assertWithMessage("Stateful field is not cleared after beginTree")
                  .that(TestUtil.isStatefulFieldClearedDuringBeginTree(check, ast, "branchVisited",
                          branchVisited -> !(boolean) branchVisited))
                  .isTrue();
          assertWithMessage("Stateful field is not cleared after beginTree")
                  .that(TestUtil.isStatefulFieldClearedDuringBeginTree(check, ast,
                          "currentRangeValue",
                          currentRangeValue -> currentRangeValue.equals(BigInteger.ZERO)))
                  .isTrue();
      }
  
      @Test
      @SuppressWarnings("unchecked")
      public void testStatefulFieldsClearedOnBeginTree2() {
          final DetailAstImpl ast = new DetailAstImpl();
          ast.setType(TokenTypes.LITERAL_RETURN);
          ast.setLineNo(5);
          final DetailAstImpl child = new DetailAstImpl();
          child.setType(TokenTypes.SEMI);
          ast.addChild(child);
  
          final NPathComplexityCheck check = new NPathComplexityCheck();
          assertWithMessage("Stateful field is not cleared after beginTree")
                  .that(TestUtil.isStatefulFieldClearedDuringBeginTree(check, ast, "afterValues",
                          isAfterValues -> ((Collection<Context>) isAfterValues).isEmpty()))
                  .isTrue();
      }
  
      @Test
      public void testStatefulFieldsClearedOnBeginTree3() throws Exception {
          final NPathComplexityCheck check = new NPathComplexityCheck();
          final Optional<DetailAST> question = TestUtil.findTokenInAstByPredicate(
              JavaParser.parseFile(new File(getPath("InputNPathComplexity.java")),
                  JavaParser.Options.WITHOUT_COMMENTS),
              ast -> ast.getType() == TokenTypes.QUESTION);
  
          assertWithMessage("Ast should contain QUESTION")
                  .that(question.isPresent())
                  .isTrue();
  
          assertWithMessage("State is not cleared on beginTree")
                  .that(TestUtil.isStatefulFieldClearedDuringBeginTree(check, question.get(),
                          "processingTokenEnd", processingTokenEnd -> {
                              return TestUtil.<Integer>getInternalState(processingTokenEnd,
                                      "endLineNo") == 0
                                      && TestUtil.<Integer>getInternalState(processingTokenEnd,
                                              "endColumnNo") == 0;
                          }))
                  .isTrue();
      }
  
      @Test
      public void testDefaultConfiguration() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputNPathComplexityDefault2.java"), expected);
      }
  
      @Test
      public void testNpathComplexityRecords() throws Exception {
          final int max = 1;
  
          final String[] expected = {
              "15:5: " + getCheckMessage(MSG_KEY, 3, max),
              "25:9: " + getCheckMessage(MSG_KEY, 2, max),
              "30:21: " + getCheckMessage(MSG_KEY, 2, max),
              "44:9: " + getCheckMessage(MSG_KEY, 3, max),
          };
  
          verifyWithInlineConfigParser(
                  getNonCompilablePath("InputNPathComplexityRecords.java"), expected);
      }
  
      @Test
      public void testNpathComplexitySwitchExpression() throws Exception {
  
          final int max = 1;
  
          final String[] expected = {
              "12:5: " + getCheckMessage(MSG_KEY, 5, max),
              "29:5: " + getCheckMessage(MSG_KEY, 5, max),
              "44:5: " + getCheckMessage(MSG_KEY, 6, max),
              "60:5: " + getCheckMessage(MSG_KEY, 6, max),
          };
  
          verifyWithInlineConfigParser(
                  getNonCompilablePath("InputNPathComplexityCheckSwitchExpression.java"),
              expected);
      }
  
      @Test
      public void testBranchVisited() throws Exception {
  
          final String[] expected = {
              "13:3: " + getCheckMessage(MSG_KEY, 37, 20),
          };
  
          verifyWithInlineConfigParser(
                  getPath("InputNPathComplexityCheckBranchVisited.java"),
              expected);
      }
  
      @Test
      public void testCount() throws Exception {
  
          final String[] expected = {
              "11:5: " + getCheckMessage(MSG_KEY, 30, 20),
              "22:5: " + getCheckMessage(MSG_KEY, 72, 20),
              "67:5: " + getCheckMessage(MSG_KEY, 23, 20),
          };
  
          verifyWithInlineConfigParser(
                  getPath("InputNPathComplexityCheckCount.java"),
              expected);
      }
  
      @Test
      public void testGetAcceptableTokens() {
          final NPathComplexityCheck npathComplexityCheckObj = new NPathComplexityCheck();
          final int[] actual = npathComplexityCheckObj.getAcceptableTokens();
          final int[] expected = {
              TokenTypes.CTOR_DEF,
              TokenTypes.METHOD_DEF,
              TokenTypes.STATIC_INIT,
              TokenTypes.INSTANCE_INIT,
              TokenTypes.LITERAL_WHILE,
              TokenTypes.LITERAL_DO,
              TokenTypes.LITERAL_FOR,
              TokenTypes.LITERAL_IF,
              TokenTypes.LITERAL_ELSE,
              TokenTypes.LITERAL_SWITCH,
              TokenTypes.CASE_GROUP,
              TokenTypes.LITERAL_TRY,
              TokenTypes.LITERAL_CATCH,
              TokenTypes.QUESTION,
              TokenTypes.LITERAL_RETURN,
              TokenTypes.LITERAL_DEFAULT,
              TokenTypes.COMPACT_CTOR_DEF,
              TokenTypes.SWITCH_RULE,
          };
          assertWithMessage("Acceptable tokens should not be null")
              .that(actual)
              .isNotNull();
          assertWithMessage("Invalid acceptable tokens")
              .that(actual)
              .isEqualTo(expected);
      }
  
      @Test
      public void testGetRequiredTokens() {
          final NPathComplexityCheck npathComplexityCheckObj = new NPathComplexityCheck();
          final int[] actual = npathComplexityCheckObj.getRequiredTokens();
          final int[] expected = {
              TokenTypes.CTOR_DEF,
              TokenTypes.METHOD_DEF,
              TokenTypes.STATIC_INIT,
              TokenTypes.INSTANCE_INIT,
              TokenTypes.LITERAL_WHILE,
              TokenTypes.LITERAL_DO,
              TokenTypes.LITERAL_FOR,
              TokenTypes.LITERAL_IF,
              TokenTypes.LITERAL_ELSE,
              TokenTypes.LITERAL_SWITCH,
              TokenTypes.CASE_GROUP,
              TokenTypes.LITERAL_TRY,
              TokenTypes.LITERAL_CATCH,
              TokenTypes.QUESTION,
              TokenTypes.LITERAL_RETURN,
              TokenTypes.LITERAL_DEFAULT,
              TokenTypes.COMPACT_CTOR_DEF,
              TokenTypes.SWITCH_RULE,
          };
          assertWithMessage("Required tokens should not be null")
              .that(actual)
              .isNotNull();
          assertWithMessage("Invalid required tokens")
              .that(actual)
              .isEqualTo(expected);
      }
  
      @Test
      public void testDefaultHooks() {
          final NPathComplexityCheck npathComplexityCheckObj = new NPathComplexityCheck();
          final DetailAstImpl ast = new DetailAstImpl();
          ast.initialize(new CommonToken(TokenTypes.INTERFACE_DEF, "interface"));
  
          npathComplexityCheckObj.visitToken(ast);
          final SortedSet<Violation> violations1 = npathComplexityCheckObj.getViolations();
  
          assertWithMessage("No exception violations expected")
              .that(violations1)
              .isEmpty();
  
          npathComplexityCheckObj.leaveToken(ast);
          final SortedSet<Violation> violations2 = npathComplexityCheckObj.getViolations();
  
          assertWithMessage("No exception violations expected")
              .that(violations2)
              .isEmpty();
      }
  
      /**
       * This must be a reflection test as it is too difficult to hit normally and
       * the responsible code can't be removed without failing tests.
       * TokenEnd is only used for processingTokenEnd and it is only set during visitConditional
       * and visitUnitaryOperator. For it to be the same line/column, it must be the exact same
       * token or a token who has the same line/column as it's child and we visit. We never
       * visit the same token twice and we are only visiting on very specific tokens.
       * The line can't be removed or reworked as other tests fail, and regression shows us no
       * use cases to create a UT for.
       *
       * @throws Exception if there is an error.
       */
      @Test
      public void testTokenEndIsAfterSameLineColumn() throws Exception {
          final NPathComplexityCheck check = new NPathComplexityCheck();
          final Object tokenEnd = TestUtil.getInternalState(check, "processingTokenEnd");
          final DetailAstImpl token = new DetailAstImpl();
          token.setLineNo(0);
          token.setColumnNo(0);
  
          assertWithMessage("isAfter must be true for same line/column")
                  .that(TestUtil.<Boolean>invokeMethod(tokenEnd, "isAfter", token))
                  .isTrue();
      }
  
      @Test
      public void testVisitTokenBeforeExpressionRange() {
          // Create first ast
          final DetailAstImpl astIf = mockAST(TokenTypes.LITERAL_IF, "if", 2, 2);
          final DetailAstImpl astIfLeftParen = mockAST(TokenTypes.LPAREN, "(", 3, 3);
          astIf.addChild(astIfLeftParen);
          final DetailAstImpl astIfTrue =
                  mockAST(TokenTypes.LITERAL_TRUE, "true", 3, 3);
          astIf.addChild(astIfTrue);
          final DetailAstImpl astIfRightParen = mockAST(TokenTypes.RPAREN, ")", 4, 4);
          astIf.addChild(astIfRightParen);
          // Create ternary ast
          final DetailAstImpl astTernary = mockAST(TokenTypes.QUESTION, "?", 1, 1);
          final DetailAstImpl astTernaryTrue =
                  mockAST(TokenTypes.LITERAL_TRUE, "true", 1, 2);
          astTernary.addChild(astTernaryTrue);
  
          final NPathComplexityCheck npathComplexityCheckObj = new NPathComplexityCheck();
          npathComplexityCheckObj.beginTree(null);
  
          // visiting first ast, set expressionSpatialRange to [2,2 - 4,4]
          npathComplexityCheckObj.visitToken(astIf);
          final SortedSet<Violation> violations1 = npathComplexityCheckObj.getViolations();
  
          assertWithMessage("No exception violations expected")
              .that(violations1)
              .isEmpty();
  
          // visiting ternary, it lies before expressionSpatialRange
          npathComplexityCheckObj.visitToken(astTernary);
          final SortedSet<Violation> violations2 = npathComplexityCheckObj.getViolations();
  
          assertWithMessage("No exception violations expected")
              .that(violations2)
              .isEmpty();
      }
  
      /**
       * Creates MOCK lexical token and returns AST node for this token.
       *
       * @param tokenType type of token
       * @param tokenText text of token
       * @param tokenRow token position in a file (row)
       * @param tokenColumn token position in a file (column)
       * @return AST node for the token
       */
      private static DetailAstImpl mockAST(final int tokenType, final String tokenText,
              final int tokenRow, final int tokenColumn) {
          final CommonToken tokenImportSemi = new CommonToken(tokenType, tokenText);
          tokenImportSemi.setLine(tokenRow);
          tokenImportSemi.setCharPositionInLine(tokenColumn);
          final DetailAstImpl astSemi = new DetailAstImpl();
          astSemi.initialize(tokenImportSemi);
          return astSemi;
      }
  
  }
  