/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.io.input;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertNotNull;
  import static org.junit.jupiter.api.Assertions.assertNull;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertThrowsExactly;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  import static org.junit.jupiter.api.Assumptions.assumeFalse;
  import static org.junit.jupiter.api.Assumptions.assumeTrue;
  
  import java.io.ByteArrayInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.Reader;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.util.concurrent.atomic.AtomicBoolean;
  
  import javax.xml.parsers.DocumentBuilder;
  import javax.xml.parsers.DocumentBuilderFactory;
  import javax.xml.parsers.ParserConfigurationException;
  
  import org.apache.commons.io.ByteOrderMark;
  import org.apache.commons.io.IOUtils;
  import org.apache.commons.io.test.CustomIOException;
  import org.apache.commons.lang3.SystemProperties;
  import org.junit.jupiter.api.Test;
  import org.w3c.dom.Document;
  import org.xml.sax.InputSource;
  import org.xml.sax.SAXException;
  import org.xml.sax.SAXParseException;
  
  /**
   * Test case for {@link BOMInputStream}.
   */
  @SuppressWarnings("ResultOfMethodCallIgnored")
  class BOMInputStreamTest {
  
      /**
       *  A mock InputStream that tracks if {@code close()} is called.
       */
      private static final class ExpectCloseInputStream extends InputStream {
          private boolean closed;
  
          public void assertCloseCalled() {
              assertTrue(closed);
          }
  
          @Override
          public void close() throws IOException {
              closed = true;
          }
  
          @Override
          public int read() throws IOException {
              return -1;
          }
      }
  
      private void assertData(final byte[] expected, final byte[] actual, final int len) {
          assertEquals(expected.length, len, "length");
          for (int ii = 0; ii < expected.length; ii++) {
              assertEquals(expected[ii], actual[ii], "byte " + ii);
          }
      }
  
      /**
       *  Creates the underlying data stream, with or without BOM.
       */
      private InputStream createUtf16BeDataStream(final byte[] baseData, final boolean addBOM) {
          byte[] data = baseData;
          if (addBOM) {
              data = new byte[baseData.length + 2];
              data[0] = (byte) 0xFE;
              data[1] = (byte) 0xFF;
              System.arraycopy(baseData, 0, data, 2, baseData.length);
          }
          return new ByteArrayInputStream(data);
      }
  
      /**
      *  Creates the underlying data stream, with or without BOM.
      */
     private InputStream createUtf16LeDataStream(final byte[] baseData, final boolean addBOM) {
         byte[] data = baseData;
         if (addBOM) {
             data = new byte[baseData.length + 2];
             data[0] = (byte) 0xFF;
             data[1] = (byte) 0xFE;
             System.arraycopy(baseData, 0, data, 2, baseData.length);
         }
         return new ByteArrayInputStream(data);
     }
 
     /**
      *  Creates the underlying data stream, with or without BOM.
      */
     private InputStream createUtf32BeDataStream(final byte[] baseData, final boolean addBOM) {
         byte[] data = baseData;
         if (addBOM) {
             data = new byte[baseData.length + 4];
             data[0] = 0;
             data[1] = 0;
             data[2] = (byte) 0xFE;
             data[3] = (byte) 0xFF;
             System.arraycopy(baseData, 0, data, 4, baseData.length);
         }
         return new ByteArrayInputStream(data);
     }
 
     /**
      *  Creates the underlying data stream, with or without BOM.
      */
     private InputStream createUtf32LeDataStream(final byte[] baseData, final boolean addBOM) {
         byte[] data = baseData;
         if (addBOM) {
             data = new byte[baseData.length + 4];
             data[0] = (byte) 0xFF;
             data[1] = (byte) 0xFE;
             data[2] = 0;
             data[3] = 0;
             System.arraycopy(baseData, 0, data, 4, baseData.length);
         }
         return new ByteArrayInputStream(data);
     }
 
     /**
      *  Creates the underlying data stream, with or without BOM.
      */
     private InputStream createUtf8Input(final byte[] baseData, final boolean addBOM) {
         byte[] data = baseData;
         if (addBOM) {
             data = new byte[baseData.length + 3];
             data[0] = (byte) 0xEF;
             data[1] = (byte) 0xBB;
             data[2] = (byte) 0xBF;
             System.arraycopy(baseData, 0, data, 3, baseData.length);
         }
         return new ByteArrayInputStream(data);
     }
 
     private boolean doesSaxSupportCharacterSet(final String charsetName) throws ParserConfigurationException, SAXException, IOException {
         final DocumentBuilder documentBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
         try (InputStream byteStream = CharSequenceInputStream.builder().setCharSequence("<?xml version=\"1.0\" encoding=\"" + charsetName + "\"?><Z/>")
                 .setCharset(charsetName).get()) {
             final InputSource is = new InputSource(byteStream);
             is.setEncoding(charsetName);
             documentBuilder.parse(is);
         } catch (final SAXParseException e) {
             if (e.getMessage().contains(charsetName)) {
                 return false;
             }
         }
         return true;
     }
 
     private boolean jvmAndSaxBothSupportCharset(final String charSetName) throws ParserConfigurationException, SAXException, IOException {
         return Charset.isSupported(charSetName) &&  doesSaxSupportCharacterSet(charSetName);
     }
 
     private void parseXml(final InputStream in) throws SAXException, IOException, ParserConfigurationException {
         final Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new InputSource(in));
         assertNotNull(doc);
         assertEquals("X", doc.getFirstChild().getNodeName());
     }
 
     private void parseXml(final Reader in) throws SAXException, IOException, ParserConfigurationException {
         final Document doc = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new InputSource(in));
         assertNotNull(doc);
         assertEquals("X", doc.getFirstChild().getNodeName());
     }
 
     private void readBOMInputStreamTwice(final String resource) throws Exception {
         try (InputStream inputStream = this.getClass().getResourceAsStream(resource)) {
             assertNotNull(inputStream);
             try (BOMInputStream bomInputStream = BOMInputStream.builder().setInputStream(inputStream).get()) {
                 bomInputStream.mark(1_000_000);
                 readFile(bomInputStream);
                 bomInputStream.reset();
                 readFile(bomInputStream);
                 inputStream.close();
             }
         }
     }
 
     private void readFile(final BOMInputStream bomInputStream) throws Exception {
         int bytes;
         final byte[] bytesFromStream = new byte[100];
         do {
             bytes = bomInputStream.read(bytesFromStream);
         } while (bytes > 0);
     }
 
     @Test
     void testAfterReadConsumer() throws Exception {
         final byte[] data = { 'A', 'B', 'C', 'D' };
         final AtomicBoolean boolRef = new AtomicBoolean();
         // @formatter:off
         try (BOMInputStream bounded = BOMInputStream.builder()
                 .setInputStream(createUtf8Input(data, true))
                 .setAfterRead(i -> boolRef.set(true))
                 .get()) {
             IOUtils.consume(bounded);
         }
         // @formatter:on
         assertTrue(boolRef.get());
         // Throwing
         final String message = "test exception message";
         // @formatter:off
         assertEquals(message, assertThrowsExactly(CustomIOException.class, () -> BOMInputStream.builder()
                 .setInputStream(createUtf8Input(data, true))
                 .setAfterRead(i -> {
                     throw new CustomIOException(message);
                 })
                 .get()).getMessage());
         // @formatter:on
     }
 
     @Test
     void testAvailableWithBOMAfterClose() throws Exception {
         final byte[] data = { 'A', 'B', 'C', 'D' };
         final InputStream shadow;
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             assertEquals(4, in.available());
             shadow = in;
         }
         assertEquals(0, shadow.available());
     }
 
     @Test
     void testAvailableWithBOMAfterOpen() throws Exception {
         final byte[] data = { 'A', 'B', 'C', 'D' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             assertEquals(4, in.available());
         }
     }
 
     @Test
     void testAvailableWithoutBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C', 'D' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             assertEquals(1, in.available());
         }
     }
 
     @Test
     void testBuilderGet() {
         // java.lang.IllegalStateException: origin == null
         assertThrows(IllegalStateException.class, () -> BOMInputStream.builder().get());
     }
 
     @Test
     // this is here for coverage
     void testClose() throws Exception {
         try (ExpectCloseInputStream del = new ExpectCloseInputStream()) {
             try (BOMInputStream in = new BOMInputStream(del)) {
                 // nothing
             }
             del.assertCloseCalled();
         }
     }
 
     @Test
     void testCloseHandleIOException() throws IOException {
         final IOException exception = new IOException();
         ProxyInputStreamTest.testCloseHandleIOException(BOMInputStream.builder().setInputStream(new BrokenInputStream(() -> exception) {
 
             @Override
             public int read() throws IOException {
                 return 'X';
             }
         }).get());
     }
 
     @Test
     void testEmptyBufferWithBOM() throws Exception {
         final byte[] data = {};
         try (InputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             final byte[] buf = new byte[1024];
             assertEquals(-1, in.read(buf));
         }
     }
 
     @Test
     void testEmptyBufferWithoutBOM() throws Exception {
         final byte[] data = {};
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             final byte[] buf = new byte[1024];
             assertEquals(-1, in.read(buf));
         }
     }
 
     @Test
     void testGetBOMFirstThenRead() throws Exception {
         final byte[] data = { 'A', 'B', 'C' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             assertEquals(ByteOrderMark.UTF_8, in.getBOM(), "getBOM");
             assertTrue(in.hasBOM(), "hasBOM()");
             assertTrue(in.hasBOM(ByteOrderMark.UTF_8), "hasBOM(UTF-8)");
             assertEquals('A', in.read());
             assertEquals('B', in.read());
             assertEquals('C', in.read());
             assertEquals(-1, in.read());
         }
     }
 
     @Test
     void testGetBOMFirstThenReadInclude() throws Exception {
         final byte[] data = { 'A', 'B', 'C' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).setInclude(true).get()) {
             assertTrue(in.hasBOM(), "hasBOM()");
             assertTrue(in.hasBOM(ByteOrderMark.UTF_8), "hasBOM(UTF-8)");
             assertEquals(ByteOrderMark.UTF_8, in.getBOM(), "getBOM");
             assertEquals(0xEF, in.read());
             assertEquals(0xBB, in.read());
             assertEquals(0xBF, in.read());
             assertEquals('A', in.read());
             assertEquals('B', in.read());
             assertEquals('C', in.read());
             assertEquals(-1, in.read());
         }
     }
 
     @Test
     void testLargeBufferWithBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             final byte[] buf = new byte[1024];
             assertData(data, buf, in.read(buf));
         }
     }
 
     @Test
     void testLargeBufferWithoutBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             final byte[] buf = new byte[1024];
             assertData(data, buf, in.read(buf));
         }
     }
 
     @Test
     void testLeadingNonBOMBufferedRead() throws Exception {
         final byte[] data = { (byte) 0xEF, (byte) 0xAB, (byte) 0xCD };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             final byte[] buf = new byte[1024];
             assertData(data, buf, in.read(buf));
         }
     }
 
     @Test
     void testLeadingNonBOMSingleRead() throws Exception {
         final byte[] data = { (byte) 0xEF, (byte) 0xAB, (byte) 0xCD };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             assertEquals(0xEF, in.read());
             assertEquals(0xAB, in.read());
             assertEquals(0xCD, in.read());
             assertEquals(-1, in.read());
         }
     }
 
     @Test
     void testMarkResetAfterReadWithBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C', 'D' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             assertTrue(in.markSupported());
             in.read();
             in.mark(10);
             in.read();
             in.read();
             in.reset();
             assertEquals('B', in.read());
         }
     }
 
     @Test
     void testMarkResetAfterReadWithoutBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C', 'D' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             assertTrue(in.markSupported());
             in.read();
             in.mark(10);
             in.read();
             in.read();
             in.reset();
             assertEquals('B', in.read());
         }
     }
 
     @Test
     void testMarkResetBeforeReadWithBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C', 'D' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             assertTrue(in.markSupported());
             in.mark(10);
             in.read();
             in.read();
             in.reset();
             assertEquals('A', in.read());
         }
     }
 
     @Test
     void testMarkResetBeforeReadWithoutBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C', 'D' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             assertTrue(in.markSupported());
             in.mark(10);
             in.read();
             in.read();
             in.reset();
             assertEquals('A', in.read());
         }
     }
 
     @Test
     void testNoBoms() throws Exception {
         final byte[] data = { 'A', 'B', 'C' };
         assertThrows(IllegalArgumentException.class, () -> new BOMInputStream(createUtf8Input(data, true), false, (ByteOrderMark[]) null).close());
         assertThrows(IllegalArgumentException.class, () -> new BOMInputStream(createUtf8Input(data, true), false, new ByteOrderMark[0]).close());
         //
         try (BOMInputStream bomInputStream = BOMInputStream.builder()
                 .setInputStream(createUtf8Input(data, true))
                 .setInclude(true)
                 .setByteOrderMarks((ByteOrderMark[]) null)
                 .get()) {
             assertEquals(BOMInputStream.Builder.getDefaultByteOrderMark(), bomInputStream.getBOM());
         }
         assertThrows(IllegalArgumentException.class, () -> BOMInputStream.builder()
                 .setInputStream(createUtf8Input(data, true))
                 .setInclude(true)
                 .setByteOrderMarks()
                 .get()
                 .close());
     }
 
     @Test
     void testReadAfterClose() throws Exception {
         final byte[] data = { 'A', 'B', 'C', 'D' };
         try (InputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             assertEquals(4, in.available());
             in.close();
             assertThrows(IOException.class, in::read);
         }
     }
 
     @Test
     void testReadEmpty() throws Exception {
         final byte[] data = {};
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             assertEquals(-1, in.read());
             assertFalse(in.hasBOM(), "hasBOM()");
             assertFalse(in.hasBOM(ByteOrderMark.UTF_8), "hasBOM(UTF-8)");
             assertNull(in.getBOM(), "getBOM");
         }
     }
 
     @Test
     void testReadSmall() throws Exception {
         final byte[] data = { 'A', 'B' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             assertEquals('A', in.read());
             assertEquals('B', in.read());
             assertEquals(-1, in.read());
             assertFalse(in.hasBOM(), "hasBOM()");
             assertFalse(in.hasBOM(ByteOrderMark.UTF_8), "hasBOM(UTF-8)");
             assertNull(in.getBOM(), "getBOM");
         }
     }
 
     @Test
     void testReadTwiceWithBOM() throws Exception {
         readBOMInputStreamTwice("/org/apache/commons/io/testfileBOM.xml");
     }
 
     @Test
     void testReadTwiceWithoutBOM() throws Exception {
         readBOMInputStreamTwice("/org/apache/commons/io/testfileNoBOM.xml");
     }
 
     @Test
     void testReadWithBOMInclude() throws Exception {
         final byte[] data = { 'A', 'B', 'C' };
         try (BOMInputStream in = new BOMInputStream(createUtf8Input(data, true), true)) {
             assertEquals(0xEF, in.read());
             assertEquals(0xBB, in.read());
             assertEquals(0xBF, in.read());
             assertEquals('A', in.read());
             assertEquals('B', in.read());
             assertEquals('C', in.read());
             assertEquals(-1, in.read());
             assertTrue(in.hasBOM(), "hasBOM()");
             assertTrue(in.hasBOM(ByteOrderMark.UTF_8), "hasBOM(UTF-8)");
             assertEquals(ByteOrderMark.UTF_8, in.getBOM(), "getBOM");
         }
     }
 
     @Test
     void testReadWithBOMUtf16Be() throws Exception {
         final byte[] data = "ABC".getBytes(StandardCharsets.UTF_16BE);
         try (BOMInputStream in = new BOMInputStream(createUtf16BeDataStream(data, true), ByteOrderMark.UTF_16BE)) {
             assertEquals(0, in.read());
             assertEquals('A', in.read());
             assertEquals(0, in.read());
             assertEquals('B', in.read());
             assertEquals(0, in.read());
             assertEquals('C', in.read());
             assertEquals(-1, in.read());
             assertTrue(in.hasBOM(), "hasBOM()");
             assertTrue(in.hasBOM(ByteOrderMark.UTF_16BE), "hasBOM(UTF-16BE)");
             assertEquals(ByteOrderMark.UTF_16BE, in.getBOM(), "getBOM");
             assertThrows(IllegalArgumentException.class, () -> in.hasBOM(ByteOrderMark.UTF_16LE));
         }
     }
 
     @Test
     void testReadWithBOMUtf16Le() throws Exception {
         final byte[] data = "ABC".getBytes(StandardCharsets.UTF_16LE);
         try (BOMInputStream in = new BOMInputStream(createUtf16LeDataStream(data, true), ByteOrderMark.UTF_16LE)) {
             assertEquals('A', in.read());
             assertEquals(0, in.read());
             assertEquals('B', in.read());
             assertEquals(0, in.read());
             assertEquals('C', in.read());
             assertEquals(0, in.read());
             assertEquals(-1, in.read());
             assertTrue(in.hasBOM(), "hasBOM()");
             assertTrue(in.hasBOM(ByteOrderMark.UTF_16LE), "hasBOM(UTF-16LE)");
             assertEquals(ByteOrderMark.UTF_16LE, in.getBOM(), "getBOM");
             assertThrows(IllegalArgumentException.class, () -> in.hasBOM(ByteOrderMark.UTF_16BE));
         }
     }
 
     @Test
     void testReadWithBOMUtf32Be() throws Exception {
         assumeTrue(Charset.isSupported("UTF_32BE"));
         final byte[] data = "ABC".getBytes("UTF_32BE");
         try (BOMInputStream in = new BOMInputStream(createUtf32BeDataStream(data, true),
                 ByteOrderMark.UTF_32BE)) {
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals('A', in.read());
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals('B', in.read());
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals('C', in.read());
             assertEquals(-1, in.read());
             assertTrue(in.hasBOM(), "hasBOM()");
             assertTrue(in.hasBOM(ByteOrderMark.UTF_32BE), "hasBOM(UTF-32BE)");
             assertEquals(ByteOrderMark.UTF_32BE, in.getBOM(), "getBOM");
             assertThrows(IllegalArgumentException.class, () -> in.hasBOM(ByteOrderMark.UTF_32LE));
         }
     }
 
     @Test
     void testReadWithBOMUtf32Le() throws Exception {
         assumeTrue(Charset.isSupported("UTF_32LE"));
         final byte[] data = "ABC".getBytes("UTF_32LE");
         try (BOMInputStream in = new BOMInputStream(createUtf32LeDataStream(data, true),
                 ByteOrderMark.UTF_32LE)) {
             assertEquals('A', in.read());
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals('B', in.read());
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals('C', in.read());
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals(0, in.read());
             assertEquals(-1, in.read());
             assertTrue(in.hasBOM(), "hasBOM()");
             assertTrue(in.hasBOM(ByteOrderMark.UTF_32LE), "hasBOM(UTF-32LE)");
             assertEquals(ByteOrderMark.UTF_32LE, in.getBOM(), "getBOM");
             assertThrows(IllegalArgumentException.class, () -> in.hasBOM(ByteOrderMark.UTF_32BE));
         }
     }
 
     @Test
     void testReadWithBOMUtf8() throws Exception {
         final byte[] data = "ABC".getBytes(StandardCharsets.UTF_8);
         try (BOMInputStream in = new BOMInputStream(createUtf8Input(data, true), ByteOrderMark.UTF_8)) {
             assertEquals('A', in.read());
             assertEquals('B', in.read());
             assertEquals('C', in.read());
             assertEquals(-1, in.read());
             assertTrue(in.hasBOM(), "hasBOM()");
             assertTrue(in.hasBOM(ByteOrderMark.UTF_8), "hasBOM(UTF-8)");
             assertEquals(ByteOrderMark.UTF_8, in.getBOM(), "getBOM");
             assertThrows(IllegalArgumentException.class, () -> in.hasBOM(ByteOrderMark.UTF_16BE));
         }
     }
 
     @Test
     void testReadWithMultipleBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C' };
         try (BOMInputStream in = new BOMInputStream(createUtf8Input(data, true), ByteOrderMark.UTF_16BE,
                 ByteOrderMark.UTF_8)) {
             assertEquals('A', in.read());
             assertEquals('B', in.read());
             assertEquals('C', in.read());
             assertEquals(-1, in.read());
             assertTrue(in.hasBOM(), "hasBOM()");
             assertTrue(in.hasBOM(ByteOrderMark.UTF_8), "hasBOM(UTF-8)");
             assertFalse(in.hasBOM(ByteOrderMark.UTF_16BE), "hasBOM(UTF-16BE)");
             assertEquals(ByteOrderMark.UTF_8, in.getBOM(), "getBOM");
         }
     }
 
     @Test
     void testReadWithoutBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C' };
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             assertEquals('A', in.read());
             assertEquals('B', in.read());
             assertEquals('C', in.read());
             assertEquals(-1, in.read());
             assertFalse(in.hasBOM(), "hasBOM()");
             assertFalse(in.hasBOM(ByteOrderMark.UTF_8), "hasBOM(UTF-8)");
             assertNull(in.getBOM(), "getBOM");
         }
     }
 
     @Test
     void testReadXmlWithBOMUcs2() throws Exception {
         assumeFalse(SystemProperties.getJavaVendor().contains("IBM"), "This test does not pass on some IBM VMs XML parsers");
 
         // UCS-2 is BE.
         assumeTrue(Charset.isSupported("ISO-10646-UCS-2"));
         final byte[] data = "<?xml version=\"1.0\" encoding=\"ISO-10646-UCS-2\"?><X/>".getBytes("ISO-10646-UCS-2");
         try (BOMInputStream in = new BOMInputStream(createUtf16BeDataStream(data, true), ByteOrderMark.UTF_16BE)) {
             parseXml(in);
         }
         parseXml(createUtf16BeDataStream(data, true));
     }
 
     @Test
     void testReadXmlWithBOMUcs4() throws Exception {
         // UCS-4 is BE or LE?
         // Hm: ISO-10646-UCS-4 is not supported on Oracle 1.6.0_31
         assumeTrue(Charset.isSupported("ISO-10646-UCS-4"));
         final byte[] data = "<?xml version=\"1.0\" encoding=\"ISO-10646-UCS-4\"?><X/>".getBytes("ISO-10646-UCS-4");
         // XML parser does not know what to do with UTF-32
         try (BOMInputStream in = new BOMInputStream(createUtf32BeDataStream(data, true), ByteOrderMark.UTF_32BE)) {
             parseXml(in);
             // XML parser does not know what to do with UTF-32
             assumeTrue(jvmAndSaxBothSupportCharset("UTF_32LE"), "JVM and SAX need to support UTF_32LE for this");
         }
         parseXml(createUtf32BeDataStream(data, true));
     }
 
     @Test
     void testReadXmlWithBOMUtf16Be() throws Exception {
         final byte[] data = "<?xml version=\"1.0\" encoding=\"UTF-16BE\"?><X/>".getBytes(StandardCharsets.UTF_16BE);
         try (BOMInputStream in = new BOMInputStream(createUtf16BeDataStream(data, true), ByteOrderMark.UTF_16BE)) {
             parseXml(in);
         }
         parseXml(createUtf16BeDataStream(data, true));
     }
 
     @Test
     void testReadXmlWithBOMUtf16Le() throws Exception {
         final byte[] data = "<?xml version=\"1.0\" encoding=\"UTF-16LE\"?><X/>".getBytes(StandardCharsets.UTF_16LE);
         try (BOMInputStream in = new BOMInputStream(createUtf16LeDataStream(data, true), ByteOrderMark.UTF_16LE)) {
             parseXml(in);
         }
         parseXml(createUtf16LeDataStream(data, true));
     }
 
     @Test
     void testReadXmlWithBOMUtf32Be() throws Exception {
         assumeTrue(jvmAndSaxBothSupportCharset("UTF_32BE"), "JVM and SAX need to support UTF_32BE for this");
         final byte[] data = "<?xml version=\"1.0\" encoding=\"UTF-32BE\"?><X/>".getBytes("UTF_32BE");
         try (BOMInputStream in = new BOMInputStream(createUtf32BeDataStream(data, true), ByteOrderMark.UTF_32BE)) {
             parseXml(in);
         }
         // XML parser does not know what to do with UTF-32, so we warp the input stream with a XmlStreamReader
         try (XmlStreamReader in = new XmlStreamReader(createUtf32BeDataStream(data, true))) {
             parseXml(in);
         }
     }
 
     @Test
     void testReadXmlWithBOMUtf32Le() throws Exception {
         assumeTrue(jvmAndSaxBothSupportCharset("UTF_32LE"), "JVM and SAX need to support UTF_32LE for this");
         final byte[] data = "<?xml version=\"1.0\" encoding=\"UTF-32LE\"?><X/>".getBytes("UTF_32LE");
         try (BOMInputStream in = new BOMInputStream(createUtf32LeDataStream(data, true), ByteOrderMark.UTF_32LE)) {
             parseXml(in);
         }
         // XML parser does not know what to do with UTF-32, so we warp the input stream with a XmlStreamReader
         try (XmlStreamReader in = new XmlStreamReader(createUtf32LeDataStream(data, true))) {
             parseXml(in);
         }
     }
 
     @Test
     void testReadXmlWithBOMUtf8() throws Exception {
         final byte[] data = "<?xml version=\"1.0\" encoding=\"UTF-8\"?><X/>".getBytes(StandardCharsets.UTF_8);
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             parseXml(in);
         }
         parseXml(createUtf8Input(data, true));
     }
 
     @Test
     void testReadXmlWithoutBOMUtf32Be() throws Exception {
         assumeTrue(jvmAndSaxBothSupportCharset("UTF_32BE"), "JVM and SAX need to support UTF_32BE for this");
         final byte[] data = "<?xml version=\"1.0\" encoding=\"UTF_32BE\"?><X/>".getBytes("UTF_32BE");
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             parseXml(in);
         }
         parseXml(createUtf32BeDataStream(data, false));
     }
 
     @Test
     void testReadXmlWithoutBOMUtf32Le() throws Exception {
         assumeTrue(jvmAndSaxBothSupportCharset("UTF_32LE"), "JVM and SAX need to support UTF_32LE for this");
         final byte[] data = "<?xml version=\"1.0\" encoding=\"UTF-32LE\"?><X/>".getBytes("UTF_32LE");
         try (BOMInputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             parseXml(in);
         }
         parseXml(createUtf32BeDataStream(data, false));
     }
 
     @Test
     void testSkipReturnValueWithBom() throws IOException {
         final byte[] data = { (byte) 0x31, (byte) 0x32, (byte) 0x33 };
         try (BOMInputStream is1 = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             assertEquals(2, is1.skip(2));
             assertEquals((byte) 0x33, is1.read());
         }
     }
 
     @Test
     void testSkipReturnValueWithoutBom() throws IOException {
         final byte[] data = { (byte) 0x31, (byte) 0x32, (byte) 0x33 };
         try (BOMInputStream is2 = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             assertEquals(2, is2.skip(2)); // IO-428
             assertEquals((byte) 0x33, is2.read());
         }
     }
 
     @Test
     void testSkipWithBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C', 'D' };
         try (InputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             in.skip(2L);
             assertEquals('C', in.read());
         }
     }
 
     @Test
     void testSkipWithoutBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C', 'D' };
         try (InputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             in.skip(2L);
             assertEquals('C', in.read());
         }
     }
 
     @Test
     void testSmallBufferWithBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C' };
         try (InputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, true)).get()) {
             final byte[] buf = new byte[1024];
             assertData(new byte[] { 'A', 'B' }, buf, in.read(buf, 0, 2));
             assertData(new byte[] { 'C' }, buf, in.read(buf, 0, 2));
         }
     }
 
     @Test
     void testSmallBufferWithoutBOM() throws Exception {
         final byte[] data = { 'A', 'B', 'C' };
         try (InputStream in = BOMInputStream.builder().setInputStream(createUtf8Input(data, false)).get()) {
             final byte[] buf = new byte[1024];
             assertData(new byte[] { 'A', 'B' }, buf, in.read(buf, 0, 2));
             assertData(new byte[] { 'C' }, buf, in.read(buf, 0, 2));
         }
     }
 
     @Test
     // make sure that our support code works as expected
     void testSupportCode() throws Exception {
         try (InputStream in = createUtf8Input(new byte[] { 'A', 'B' }, true)) {
             final byte[] buf = new byte[1024];
             final int len = in.read(buf);
             assertEquals(5, len);
             assertEquals(0xEF, buf[0] & 0xFF);
             assertEquals(0xBB, buf[1] & 0xFF);
             assertEquals(0xBF, buf[2] & 0xFF);
             assertEquals('A', buf[3] & 0xFF);
             assertEquals('B', buf[4] & 0xFF);
 
             assertData(new byte[] { (byte) 0xEF, (byte) 0xBB, (byte) 0xBF, 'A', 'B' }, buf, len);
         }
     }
 }