### Question:
ByteArrayInputStreamWithPos extends InputStream { public void setBuffer(byte[] buffer, int offset, int length) { this.count = Math.min(buffer.length, offset + length); setPosition(offset); this.buffer = buffer; this.mark = offset; } ByteArrayInputStreamWithPos();  ByteArrayInputStreamWithPos(byte[] buffer);  ByteArrayInputStreamWithPos(byte[] buffer, int offset, int length); @Override int read(); @Override int read(byte[] b, int off, int len); @Override long skip(long toSkip); @Override boolean markSupported(); @Override void mark(int readAheadLimit); @Override void reset(); @Override int available(); @Override void close(); int getPosition(); void setPosition(int pos); void setBuffer(byte[] buffer, int offset, int length);  }### Answer:
@Test public void testSetBuffer() { ByteArrayInputStreamWithPos in = new ByteArrayInputStreamWithPos(); Assert.assertEquals(-1, in.read()); byte[] testData = new byte[]{0x42, 0x43, 0x44, 0x45}; int off = 1; int len = 2; in.setBuffer(testData, off, len); for (int i = 0; i < len; ++i) { Assert.assertEquals(testData[i + off], in.read()); } Assert.assertEquals(-1, in.read()); }