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.api;
  
  import static com.google.common.truth.Truth.assertWithMessage;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  
  import java.util.Set;
  import java.util.regex.Pattern;
  
  import org.junit.jupiter.api.Test;
  
  import com.puppycrawl.tools.checkstyle.filefilters.BeforeExecutionExclusionFileFilter;
  
  public class BeforeExecutionFileFilterSetTest {
  
      @Test
      public void testRemoveFilters() {
          final BeforeExecutionFileFilterSet filterSet = new BeforeExecutionFileFilterSet();
          final BeforeExecutionFileFilter filter = new BeforeExecutionExclusionFileFilter();
          filterSet.addBeforeExecutionFileFilter(filter);
          filterSet.removeBeforeExecutionFileFilter(filter);
          assertWithMessage("size is the same")
                  .that(filterSet.getBeforeExecutionFileFilters())
                  .isEmpty();
      }
  
      @Test
      public void testAccept() {
          final String fileName = "BAD";
          final BeforeExecutionExclusionFileFilter filter = new BeforeExecutionExclusionFileFilter();
          filter.setFileNamePattern(Pattern.compile(fileName));
          final BeforeExecutionFileFilterSet set = new BeforeExecutionFileFilterSet();
          set.addBeforeExecutionFileFilter(filter);
  
          assertWithMessage("Invalid accept state, should accept")
                  .that(set.accept("ATest.java"))
                  .isTrue();
      }
  
      @Test
      public void testReject() {
          final String fileName = "Test";
          final BeforeExecutionExclusionFileFilter filter = new BeforeExecutionExclusionFileFilter();
          filter.setFileNamePattern(Pattern.compile(fileName));
          final BeforeExecutionFileFilterSet set = new BeforeExecutionFileFilterSet();
          set.addBeforeExecutionFileFilter(filter);
  
          assertWithMessage("Invalid accept state, should not accept")
                  .that(set.accept("ATest.java"))
                  .isFalse();
      }
  
      @Test
      public void testGetFilters2() {
          final BeforeExecutionFileFilterSet filterSet = new BeforeExecutionFileFilterSet();
          filterSet.addBeforeExecutionFileFilter(new BeforeExecutionExclusionFileFilter());
          assertWithMessage("size is the same")
                  .that(filterSet.getBeforeExecutionFileFilters())
                  .hasSize(1);
      }
  
      @Test
      public void testToString2() {
          final BeforeExecutionFileFilterSet filterSet = new BeforeExecutionFileFilterSet();
          filterSet.addBeforeExecutionFileFilter(new BeforeExecutionExclusionFileFilter());
          assertWithMessage("size is the same")
                  .that(filterSet.toString())
                  .isNotNull();
      }
  
      @Test
      public void testClear() {
          final BeforeExecutionFileFilterSet filterSet = new BeforeExecutionFileFilterSet();
          filterSet.addBeforeExecutionFileFilter(new BeforeExecutionExclusionFileFilter());
  
          assertWithMessage("Invalid filter set size")
                  .that(filterSet.getBeforeExecutionFileFilters())
                  .hasSize(1);
  
          filterSet.clear();
  
          assertWithMessage("Invalid filter set size")
                  .that(filterSet.getBeforeExecutionFileFilters())
                  .isEmpty();
      }
  
      /*
        Due to low level configuration setup of BeforeExecutionFileFilterSet, conventional
        input validation cannot be done here hence, pure JUnit testing has been
        done for the time being
      */
      @Test
      public void testUnmodifiableSet() {
          final BeforeExecutionFileFilterSet filterSet = new BeforeExecutionFileFilterSet();
          final BeforeExecutionFileFilter filter = new BeforeExecutionExclusionFileFilter();
          filterSet.addBeforeExecutionFileFilter(filter);
          final Set<BeforeExecutionFileFilter> excFilterSet =
              filterSet.getBeforeExecutionFileFilters();
          assertThrows(UnsupportedOperationException.class,
              () -> excFilterSet.add(filter));
      }
  
      /*
        Input based test does not call toString, but this method might be
        useful for third party integrations.
      */
      @Test
      public void testEmptyToString() {
          final BeforeExecutionFileFilterSet filterSet = new BeforeExecutionFileFilterSet();
          assertWithMessage("toString() result shouldn't be an empty string")
                  .that(filterSet.toString())
                  .isNotEmpty();
      }
  
  }
  