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.regexp;
  
  import static com.google.common.truth.Truth.assertWithMessage;
  import static com.puppycrawl.tools.checkstyle.checks.regexp.MultilineDetector.MSG_EMPTY;
  import static com.puppycrawl.tools.checkstyle.checks.regexp.MultilineDetector.MSG_REGEXP_EXCEEDED;
  import static com.puppycrawl.tools.checkstyle.checks.regexp.MultilineDetector.MSG_REGEXP_MINIMUM;
  import static com.puppycrawl.tools.checkstyle.checks.regexp.MultilineDetector.MSG_STACKOVERFLOW;
  
  import java.io.File;
  import java.nio.charset.StandardCharsets;
  import java.nio.file.Files;
  
  import org.junit.jupiter.api.Test;
  import org.junit.jupiter.api.io.TempDir;
  
  import com.puppycrawl.tools.checkstyle.AbstractModuleTestSupport;
  import com.puppycrawl.tools.checkstyle.DefaultConfiguration;
  import com.puppycrawl.tools.checkstyle.api.FileText;
  import com.puppycrawl.tools.checkstyle.internal.testmodules.TestLoggingReporter;
  import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
  
  public class RegexpMultilineCheckTest extends AbstractModuleTestSupport {
  
      @TempDir
      public File temporaryFolder;
  
      @Override
      protected String getPackageLocation() {
          return "com/puppycrawl/tools/checkstyle/checks/regexp/regexpmultiline";
      }
  
      @Test
      public void testIt() throws Exception {
          final String[] expected = {
              "78: " + getCheckMessage(MSG_REGEXP_EXCEEDED, "System\\.(out)|(err)\\.print(ln)?\\("),
          };
          verifyWithInlineConfigParser(
                  getPath("InputRegexpMultilineSemantic.java"), expected);
      }
  
      @Test
      public void testMessageProperty()
              throws Exception {
          final String[] expected = {
              "79: " + "Bad line :(",
          };
          verifyWithInlineConfigParser(
                  getPath("InputRegexpMultilineSemantic2.java"), expected);
      }
  
      @Test
      public void testIgnoreCaseTrue() throws Exception {
          final String[] expected = {
              "79: " + getCheckMessage(MSG_REGEXP_EXCEEDED, "SYSTEM\\.(OUT)|(ERR)\\.PRINT(LN)?\\("),
          };
          verifyWithInlineConfigParser(
                  getPath("InputRegexpMultilineSemantic3.java"), expected);
      }
  
      @Test
      public void testIgnoreCaseFalse() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputRegexpMultilineSemantic4.java"), expected);
      }
  
      @Test
      public void testIllegalFailBelowErrorLimit() throws Exception {
          final String[] expected = {
              "16: " + getCheckMessage(MSG_REGEXP_EXCEEDED, "^import"),
              "17: " + getCheckMessage(MSG_REGEXP_EXCEEDED, "^import"),
              "18: " + getCheckMessage(MSG_REGEXP_EXCEEDED, "^import"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputRegexpMultilineSemantic5.java"), expected);
      }
  
      @Test
      public void testCarriageReturn() throws Exception {
          final DefaultConfiguration checkConfig = createModuleConfig(RegexpMultilineCheck.class);
          checkConfig.addProperty("format", "\\r");
          checkConfig.addProperty("maximum", "0");
          final String[] expected = {
              "1: " + getCheckMessage(MSG_REGEXP_EXCEEDED, "\\r"),
              "3: " + getCheckMessage(MSG_REGEXP_EXCEEDED, "\\r"),
          };
  
          final File file = File.createTempFile("junit", null, temporaryFolder);
          Files.write(file.toPath(),
              "first line \r\n second line \n\r third line".getBytes(StandardCharsets.UTF_8));
  
          verify(checkConfig, file.getPath(), expected);
      }
  
      @Test
      public void testMaximum() throws Exception {
          final DefaultConfiguration checkConfig = createModuleConfig(RegexpMultilineCheck.class);
          checkConfig.addProperty("format", "\\r");
          checkConfig.addProperty("maximum", "1");
          final String[] expected = {
              "3: " + getCheckMessage(MSG_REGEXP_EXCEEDED, "\\r"),
          };
  
          final File file = File.createTempFile("junit", null, temporaryFolder);
          Files.write(file.toPath(),
                  "first line \r\n second line \n\r third line".getBytes(StandardCharsets.UTF_8));
  
          verify(checkConfig, file.getPath(), expected);
      }
  
      /**
       * Done as a UT cause new instance of Detector is created each time 'verify' executed.
       *
       * @throws Exception some Exception
       */
      @Test
      public void testStateIsBeingReset() throws Exception {
          final TestLoggingReporter reporter = new TestLoggingReporter();
          final DetectorOptions detectorOptions = DetectorOptions.newBuilder()
                  .reporter(reporter)
                  .format("\\r")
                  .maximum(1)
                  .build();
  
          final MultilineDetector detector =
                  new MultilineDetector(detectorOptions);
          final File file = File.createTempFile("junit", null, temporaryFolder);
          Files.write(file.toPath(),
                  "first line \r\n second line \n\r third line".getBytes(StandardCharsets.UTF_8));
  
          detector.processLines(new FileText(file, StandardCharsets.UTF_8.name()));
          detector.processLines(new FileText(file, StandardCharsets.UTF_8.name()));
          assertWithMessage("Logged unexpected amount of issues")
                  .that(reporter.getLogCount())
                  .isEqualTo(2);
      }
  
      @Test
      public void testDefaultConfiguration() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputRegexpMultilineSemantic6.java"), expected);
      }
  
      @Test
      public void testNullFormat() throws Exception {
          final String[] expected = {
              "1: " + getCheckMessage(MSG_EMPTY),
          };
          verifyWithInlineConfigParser(
                  getPath("InputRegexpMultilineSemantic7.java"), expected);
      }
  
      @Test
      public void testEmptyFormat() throws Exception {
          final String[] expected = {
              "1: " + getCheckMessage(MSG_EMPTY),
          };
          verifyWithInlineConfigParser(
                  getPath("InputRegexpMultilineSemantic8.java"), expected);
      }
  
      @Test
      public void testNoStackOverflowError() throws Exception {
          final DefaultConfiguration checkConfig = createModuleConfig(RegexpMultilineCheck.class);
          // http://madbean.com/2004/mb2004-20/
          checkConfig.addProperty("format", "(x|y)*");
  
          final String[] expected = {
              "1: " + getCheckMessage(MSG_STACKOVERFLOW),
          };
  
          final File file = File.createTempFile("junit", null, temporaryFolder);
          Files.write(file.toPath(), makeLargeXyString().toString().getBytes(StandardCharsets.UTF_8));
  
          verify(checkConfig, file.getPath(), expected);
      }
  
      @Test
      public void testMinimum() throws Exception {
          final DefaultConfiguration checkConfig = createModuleConfig(RegexpMultilineCheck.class);
          checkConfig.addProperty("format", "\\r");
          checkConfig.addProperty("minimum", "5");
          final String[] expected = {
              "1: " + getCheckMessage(MSG_REGEXP_MINIMUM, "5", "\\r"),
          };
  
          final File file = File.createTempFile("junit", null, temporaryFolder);
          Files.write(file.toPath(), "".getBytes(StandardCharsets.UTF_8));
  
          verify(checkConfig, file.getPath(), expected);
      }
  
      @Test
      public void testMinimumWithCustomMessage() throws Exception {
          final DefaultConfiguration checkConfig = createModuleConfig(RegexpMultilineCheck.class);
          checkConfig.addProperty("format", "\\r");
          checkConfig.addProperty("minimum", "5");
          checkConfig.addProperty("message", "some message");
          final String[] expected = {
              "1: some message",
          };
  
          final File file = File.createTempFile("junit", null, temporaryFolder);
          Files.write(file.toPath(), "".getBytes(StandardCharsets.UTF_8));
  
          verify(checkConfig, file.getPath(), expected);
      }
  
      private static CharSequence makeLargeXyString() {
          // now needs 10'000 or 100'000, as just 1000 is no longer enough today to provoke the
          // StackOverflowError
          final int size = 100_000;
          return "xy".repeat(size / 2);
      }
  
      @Test
      public void testGoodLimit() throws Exception {
          final String[] expected = CommonUtil.EMPTY_STRING_ARRAY;
          verifyWithInlineConfigParser(
                  getPath("InputRegexpMultilineSemantic9.java"), expected);
      }
  
      @Test
      public void testMultilineSupport() throws Exception {
          final String[] expected = {
              "22: " + getCheckMessage(MSG_REGEXP_EXCEEDED, "(a)bc.*def"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputRegexpMultilineMultilineSupport.java"), expected);
      }
  
      @Test
      public void testMultilineSupportNotGreedy() throws Exception {
          final String[] expected = {
              "22: " + getCheckMessage(MSG_REGEXP_EXCEEDED, "(a)bc.*?def"),
              "24: " + getCheckMessage(MSG_REGEXP_EXCEEDED, "(a)bc.*?def"),
          };
          verifyWithInlineConfigParser(
                  getPath("InputRegexpMultilineMultilineSupport2.java"), expected);
      }
  
  }
  