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.whitespace;
  
  import static com.google.common.truth.Truth.assertWithMessage;
  import static com.puppycrawl.tools.checkstyle.checks.whitespace.GenericWhitespaceCheck.MSG_WS_FOLLOWED;
  import static com.puppycrawl.tools.checkstyle.checks.whitespace.GenericWhitespaceCheck.MSG_WS_ILLEGAL_FOLLOW;
  import static com.puppycrawl.tools.checkstyle.checks.whitespace.GenericWhitespaceCheck.MSG_WS_NOT_PRECEDED;
  import static com.puppycrawl.tools.checkstyle.checks.whitespace.GenericWhitespaceCheck.MSG_WS_PRECEDED;
  
  import java.io.File;
  import java.nio.charset.StandardCharsets;
  import java.util.Optional;
  
  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.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.FileContents;
  import com.puppycrawl.tools.checkstyle.api.FileText;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.internal.utils.TestUtil;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  
  public class GenericWhitespaceCheckTest
      extends AbstractModuleTestSupport {
  
      @Override
      protected String getPackageLocation() {
          return "com/puppycrawl/tools/checkstyle/checks/whitespace/genericwhitespace";
      }
  
      @Test
      public void testGetRequiredTokens() {
          final GenericWhitespaceCheck checkObj = new GenericWhitespaceCheck();
          final int[] expected = {
              TokenTypes.GENERIC_START,
              TokenTypes.GENERIC_END,
          };
          assertWithMessage("Default required tokens are invalid")
              .that(checkObj.getRequiredTokens())
              .isEqualTo(expected);
      }
  
      @Test
      public void testDefault() throws Exception {
          final String[] expected = {
              "22:14: " + getCheckMessage(MSG_WS_PRECEDED, "<"),
              "22:14: " + getCheckMessage(MSG_WS_FOLLOWED, "<"),
              "22:24: " + getCheckMessage(MSG_WS_PRECEDED, ">"),
              "22:44: " + getCheckMessage(MSG_WS_PRECEDED, "<"),
              "22:44: " + getCheckMessage(MSG_WS_FOLLOWED, "<"),
              "22:54: " + getCheckMessage(MSG_WS_PRECEDED, ">"),
              "23:14: " + getCheckMessage(MSG_WS_PRECEDED, "<"),
              "23:14: " + getCheckMessage(MSG_WS_FOLLOWED, "<"),
              "23:21: " + getCheckMessage(MSG_WS_PRECEDED, "<"),
              "23:21: " + getCheckMessage(MSG_WS_FOLLOWED, "<"),
              "23:31: " + getCheckMessage(MSG_WS_PRECEDED, ">"),
              "23:31: " + getCheckMessage(MSG_WS_FOLLOWED, ">"),
              "23:33: " + getCheckMessage(MSG_WS_PRECEDED, ">"),
              "23:53: " + getCheckMessage(MSG_WS_PRECEDED, "<"),
              "23:53: " + getCheckMessage(MSG_WS_FOLLOWED, "<"),
              "23:60: " + getCheckMessage(MSG_WS_PRECEDED, "<"),
              "23:60: " + getCheckMessage(MSG_WS_FOLLOWED, "<"),
              "23:70: " + getCheckMessage(MSG_WS_PRECEDED, ">"),
              "23:70: " + getCheckMessage(MSG_WS_FOLLOWED, ">"),
              "23:72: " + getCheckMessage(MSG_WS_PRECEDED, ">"),
              "36:18: " + getCheckMessage(MSG_WS_NOT_PRECEDED, "<"),
              "36:20: " + getCheckMessage(MSG_WS_ILLEGAL_FOLLOW, ">"),
              "48:22: " + getCheckMessage(MSG_WS_PRECEDED, "<"),
              "48:29: " + getCheckMessage(MSG_WS_FOLLOWED, ">"),
              "66:35: " + getCheckMessage(MSG_WS_NOT_PRECEDED, "&"),
              "69:35: " + getCheckMessage(MSG_WS_FOLLOWED, ">"),
              "87:28: " + getCheckMessage(MSG_WS_NOT_PRECEDED, "<"),
              "88:34: " + getCheckMessage(MSG_WS_FOLLOWED, ">"),
              "89:34: " + getCheckMessage(MSG_WS_NOT_PRECEDED, "<"),
              "89:41: " + getCheckMessage(MSG_WS_FOLLOWED, ">"),
              "92:26: " + getCheckMessage(MSG_WS_NOT_PRECEDED, "<"),
              "93:35: " + getCheckMessage(MSG_WS_FOLLOWED, ">"),
              "94:35: " + getCheckMessage(MSG_WS_NOT_PRECEDED, "<"),
              "94:42: " + getCheckMessage(MSG_WS_FOLLOWED, ">"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputGenericWhitespaceDefault.java"), expected);
      }
  
      @Test
      public void testAtTheStartOfTheLine() throws Exception {
          final String[] expected = {
              "16:2: " + getCheckMessage(MSG_WS_PRECEDED, ">"),
              "18:2: " + getCheckMessage(MSG_WS_PRECEDED, "<"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputGenericWhitespaceAtStartOfTheLine.java"), expected);
      }
  
      @Test
      public void testNestedGeneric() throws Exception {
          final String[] expected = {
              "17:1: " + getCheckMessage(MSG_WS_NOT_PRECEDED, "&"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputGenericWhitespaceNested.java"), expected);
      }
  
      @Test
      public void testList() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputGenericWhitespaceList.java"), expected);
      }
  
      @Test
      public void testInnerClass() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputGenericWhitespaceInnerClass.java"), expected);
      }
  
      @Test
      public void testMethodReferences() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputGenericWhitespaceMethodRef1.java"), expected);
      }
  
      @Test
      public void testMethodReferences2() throws Exception {
          final String[] expected = {
              "16:37: " + getCheckMessage(MSG_WS_FOLLOWED, ">"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputGenericWhitespaceMethodRef2.java"), expected);
      }
  
      @Test
      public void testGenericEndsTheLine() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputGenericWhitespaceEndsTheLine.java"), expected);
      }
  
      @Test
      public void testGenericWhitespaceWithEmoji() throws Exception {
          final String[] expected = {
              "35:2: " + getCheckMessage(MSG_WS_PRECEDED, '>'),
              "40:35: " + getCheckMessage(MSG_WS_PRECEDED, '<'),
              "40:42: " + getCheckMessage(MSG_WS_FOLLOWED, '>'),
              "44:28: " + getCheckMessage(MSG_WS_NOT_PRECEDED, '<'),
              "45:53: " + getCheckMessage(MSG_WS_PRECEDED, '<'),
          };
          verifyWithInlineConfigParser(
                  getPath("InputGenericWhitespaceWithEmoji.java"), expected);
      }
  
      /**
       * Checks if the private field {@code depth} is properly cleared during the
       * start of processing the next file in the check.
       *
       * @throws Exception if there is an error.
       */
      @Test
      public void testClearState() throws Exception {
          final GenericWhitespaceCheck check = new GenericWhitespaceCheck();
          final FileText fileText = new FileText(
                  new File(getPath("InputGenericWhitespaceDefault.java")),
                  StandardCharsets.UTF_8.name());
          check.setFileContents(new FileContents(fileText));
          final DetailAST root = JavaParser.parseFileText(fileText,
                  JavaParser.Options.WITHOUT_COMMENTS);
          final Optional<DetailAST> genericStart = TestUtil.findTokenInAstByPredicate(root,
              ast -> ast.getType() == TokenTypes.GENERIC_START);
  
          assertWithMessage("Ast should contain GENERIC_START")
                  .that(genericStart.isPresent())
                  .isTrue();
          assertWithMessage("State is not cleared on beginTree")
                  .that(
                      TestUtil.isStatefulFieldClearedDuringBeginTree(check, genericStart.get(),
                              "depth",
                              depth -> ((Number) depth).intValue() == 0))
                  .isTrue();
      }
  
      @Test
      public void testGetAcceptableTokens() {
          final GenericWhitespaceCheck genericWhitespaceCheckObj = new GenericWhitespaceCheck();
          final int[] actual = genericWhitespaceCheckObj.getAcceptableTokens();
          final int[] expected = {
              TokenTypes.GENERIC_START,
              TokenTypes.GENERIC_END,
          };
          assertWithMessage("Default acceptable tokens are invalid")
              .that(actual)
              .isEqualTo(expected);
      }
  
      @Test
      public void testWrongTokenType() {
          final GenericWhitespaceCheck genericWhitespaceCheckObj = new GenericWhitespaceCheck();
          final DetailAstImpl ast = new DetailAstImpl();
          ast.initialize(new CommonToken(TokenTypes.INTERFACE_DEF, "interface"));
          try {
              genericWhitespaceCheckObj.visitToken(ast);
              assertWithMessage("exception expected").fail();
          }
          catch (IllegalArgumentException ex) {
              assertWithMessage("Invalid exception message")
                  .that(ex.getMessage())
                  .isEqualTo("Unknown type interface[0x-1]");
          }
      }
  
  }
  