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.grammar.comments;
  
  import static com.google.common.truth.Truth.assertWithMessage;
  
  import java.nio.charset.StandardCharsets;
  import java.util.LinkedHashSet;
  import java.util.Set;
  
  import org.junit.jupiter.api.Test;
  
  import com.puppycrawl.tools.checkstyle.AbstractModuleTestSupport;
  import com.puppycrawl.tools.checkstyle.DefaultConfiguration;
  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
  import com.puppycrawl.tools.checkstyle.api.DetailAST;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  import com.puppycrawl.tools.checkstyle.internal.utils.CheckUtil;
  
  public class AllSinglelineCommentsTest extends AbstractModuleTestSupport {
  
      private static final Set<String> ALL_COMMENTS = new LinkedHashSet<>();
  
      private static String lineSeparator;
  
      @Override
      protected String getPackageLocation() {
          return "com/puppycrawl/tools/checkstyle/grammar/comments";
      }
  
      @Test
      public void testAllSinglelineComments() throws Exception {
          final DefaultConfiguration checkConfig =
              createModuleConfig(SinglelineCommentListenerCheck.class);
          final String path = getPath("InputFullOfSinglelineComments.java");
          lineSeparator = CheckUtil.getLineSeparatorForFile(path, StandardCharsets.UTF_8);
          execute(checkConfig, path);
          assertWithMessage("All comments should be empty")
              .that(ALL_COMMENTS)
              .isEmpty();
      }
  
      public static class SinglelineCommentListenerCheck extends AbstractCheck {
  
          @Override
          public boolean isCommentNodesRequired() {
              return true;
          }
  
          @Override
          public int[] getDefaultTokens() {
              return getAcceptableTokens();
          }
  
          @Override
          public int[] getAcceptableTokens() {
              return new int[] {TokenTypes.SINGLE_LINE_COMMENT};
          }
  
          @Override
          public int[] getRequiredTokens() {
              return getAcceptableTokens();
          }
  
          @Override
          public void init() {
              final int lines = 63;
              for (int i = 0; i < lines; i++) {
                  ALL_COMMENTS.add(i + lineSeparator);
              }
              ALL_COMMENTS.add(String.valueOf(lines));
          }
  
          @Override
          public void visitToken(DetailAST ast) {
              final String commentContent = ast.getFirstChild().getText();
              assertWithMessage("Unexpected comment: %s", commentContent)
                      .that(ALL_COMMENTS.remove(commentContent))
                      .isTrue();
          }
  
      }
  
  }
  