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.naming;
  
  import static com.google.common.truth.Truth.assertWithMessage;
  import static com.puppycrawl.tools.checkstyle.checks.naming.AbstractNameCheck.MSG_INVALID_PATTERN;
  
  import org.junit.jupiter.api.Test;
  
  import com.puppycrawl.tools.checkstyle.AbstractModuleTestSupport;
  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
  
  public class PatternVariableNameCheckTest
          extends AbstractModuleTestSupport {
  
      @Override
      protected String getPackageLocation() {
          return "com/puppycrawl/tools/checkstyle/checks/naming/patternvariablename";
      }
  
      @Test
      public void testGetAcceptableTokens() {
          final PatternVariableNameCheck patternVariableNameCheck = new PatternVariableNameCheck();
          final int[] expected = {TokenTypes.PATTERN_VARIABLE_DEF};
  
          assertWithMessage("Default acceptable tokens are invalid")
                  .that(patternVariableNameCheck.getAcceptableTokens())
                  .isEqualTo(expected);
      }
  
      @Test
      public void testDefault() throws Exception {
  
          final String pattern = "^[a-z][a-zA-Z0-9]*$";
  
          final String[] expected = {
              "18:39: " + getCheckMessage(MSG_INVALID_PATTERN, "OTHER", pattern),
              "28:34: " + getCheckMessage(MSG_INVALID_PATTERN, "Count", pattern),
              "43:36: " + getCheckMessage(MSG_INVALID_PATTERN, "S", pattern),
              "44:42: " + getCheckMessage(MSG_INVALID_PATTERN, "STRING", pattern),
              "47:34: " + getCheckMessage(MSG_INVALID_PATTERN, "STRING", pattern),
              "48:43: " + getCheckMessage(MSG_INVALID_PATTERN, "STRING", pattern),
              "60:37: " + getCheckMessage(MSG_INVALID_PATTERN, "INTEGER", pattern),
              "66:43: " + getCheckMessage(MSG_INVALID_PATTERN, "Thing1", pattern),
              "70:41: " + getCheckMessage(MSG_INVALID_PATTERN, "Thing2", pattern),
          };
          verifyWithInlineConfigParser(
                  getNonCompilablePath(
                          "InputPatternVariableNameEnhancedInstanceofTestDefault.java"),
                  expected);
      }
  
      @Test
      public void testPatternVariableNameNoSingleChar() throws Exception {
  
          final String pattern = "^[a-z][a-zA-Z0-9]+$";
  
          final String[] expected = {
              "18:39: " + getCheckMessage(MSG_INVALID_PATTERN, "OTHER", pattern),
              "23:33: " + getCheckMessage(MSG_INVALID_PATTERN, "s", pattern),
              "28:34: " + getCheckMessage(MSG_INVALID_PATTERN, "Count", pattern),
              "43:36: " + getCheckMessage(MSG_INVALID_PATTERN, "S", pattern),
              "44:42: " + getCheckMessage(MSG_INVALID_PATTERN, "STRING", pattern),
              "46:34: " + getCheckMessage(MSG_INVALID_PATTERN, "STRING", pattern),
              "47:43: " + getCheckMessage(MSG_INVALID_PATTERN, "STRING", pattern),
              "49:57: " + getCheckMessage(MSG_INVALID_PATTERN, "s", pattern),
              "56:48: " + getCheckMessage(MSG_INVALID_PATTERN, "a", pattern),
              "57:39: " + getCheckMessage(MSG_INVALID_PATTERN, "x", pattern),
              "58:43: " + getCheckMessage(MSG_INVALID_PATTERN, "y", pattern),
              "60:37: " + getCheckMessage(MSG_INVALID_PATTERN, "INTEGER", pattern),
              "65:43: " + getCheckMessage(MSG_INVALID_PATTERN, "Thing1", pattern),
              "69:41: " + getCheckMessage(MSG_INVALID_PATTERN, "Thing2", pattern),
              "74:38: " + getCheckMessage(MSG_INVALID_PATTERN, "j", pattern),
              "75:36: " + getCheckMessage(MSG_INVALID_PATTERN, "j", pattern),
              "76:37: " + getCheckMessage(MSG_INVALID_PATTERN, "j", pattern),
              "83:41: " + getCheckMessage(MSG_INVALID_PATTERN, "s", pattern),
          };
  
          verifyWithInlineConfigParser(
                  getNonCompilablePath(
                          "InputPatternVariableNameEnhancedInstanceofNoSingleChar.java"),
                  expected);
      }
  }
  