joinHelper(1, 1, 1, 1, 1, 1, 1, 1);
    joinHelper(1, 0, 1, 0, 1, 0, 1, 0);
  }

  public void testOnlyOneOpen() throws Exception {
    ByteSource source = newByteSource(0, 50);
    int[] counter = new int[1];
    ByteSource checker =
        new ByteSource() {
          @Override
          public InputStream openStream() throws IOException {
            if (counter[0]++ != 0) {

    joinHelper(1, 1, 1, 1, 1, 1, 1, 1);
    joinHelper(1, 0, 1, 0, 1, 0, 1, 0);
  }

  public void testOnlyOneOpen() throws Exception {
    ByteSource source = newByteSource(0, 50);
    int[] counter = new int[1];
    ByteSource checker =
        new ByteSource() {
          @Override
          public InputStream openStream() throws IOException {
            if (counter[0]++ != 0) {

    ByteSource source = out.asByteSource();
    int chunk1 = min(dataSize, fileThreshold);
    int chunk2 = dataSize - chunk1;

    // Write just enough to not trip the threshold
    if (chunk1 > 0) {
      write(out, data, 0, chunk1, singleByte);
      assertTrue(ByteSource.wrap(data).slice(0, chunk1).contentEquals(source));
    }
    File file = out.getFile();

    ByteSource source = out.asByteSource();
    int chunk1 = min(dataSize, fileThreshold);
    int chunk2 = dataSize - chunk1;

    // Write just enough to not trip the threshold
    if (chunk1 > 0) {
      write(out, data, 0, chunk1, singleByte);
      assertTrue(ByteSource.wrap(data).slice(0, chunk1).contentEquals(source));
    }
    File file = out.getFile();

    suite.addTestSuite(FilesTest.class);
    return suite;
  }

  public void testRoundTripSources() throws Exception {
    File asciiFile = getTestFile("ascii.txt");
    ByteSource byteSource = Files.asByteSource(asciiFile);
    assertSame(byteSource, byteSource.asCharSource(UTF_8).asByteSource(UTF_8));
  }

  public void testToByteArray() throws IOException {
    File asciiFile = getTestFile("ascii.txt");

    assertFreshInstanceReturned(
        ByteArrayOutputStream.class, OutputStream.class,
        Writer.class, StringWriter.class,
        PrintStream.class, PrintWriter.class);
    assertEquals(ByteSource.empty(), ArbitraryInstances.get(ByteSource.class));
    assertEquals(CharSource.empty(), ArbitraryInstances.get(CharSource.class));
    assertThat(ArbitraryInstances.get(ByteSink.class)).isNotNull();

    suite.addTestSuite(FilesTest.class);
    return suite;
  }

  public void testRoundTripSources() throws Exception {
    File asciiFile = getTestFile("ascii.txt");
    ByteSource byteSource = Files.asByteSource(asciiFile);
    assertSame(byteSource, byteSource.asCharSource(UTF_8).asByteSource(UTF_8));
  }

  public void testToByteArray() throws IOException {
    File asciiFile = getTestFile("ascii.txt");

    assertFreshInstanceReturned(
        ByteArrayOutputStream.class, OutputStream.class,
        Writer.class, StringWriter.class,
        PrintStream.class, PrintWriter.class);
    assertEquals(ByteSource.empty(), ArbitraryInstances.get(ByteSource.class));
    assertEquals(CharSource.empty(), ArbitraryInstances.get(CharSource.class));
    assertThat(ArbitraryInstances.get(ByteSink.class)).isNotNull();

  /**
   * Returns a {@code ByteSource} that reads base-encoded bytes from the specified {@code
   * CharSource}.
   */
  @J2ktIncompatible
  @GwtIncompatible // ByteSource,CharSource
  public final ByteSource decodingSource(CharSource encodedSource) {
    checkNotNull(encodedSource);
    return new ByteSource() {
      @Override
      public InputStream openStream() throws IOException {