@Override
      public void append(LogSegment segment, ByteBuffer buffer) throws StoreException {
        int writeSize = buffer.remaining();
        int written = segment.appendFrom(buffer);
        assertEquals("Size written did not match size of buffer provided", writeSize, written);
      }
Tests {@link LogSegment#appendFrom(ByteBuffer)} and {@link LogSegment#appendFrom(ReadableByteChannel, long)} for
various cases.
@throws IOException
ambry-store/src/test/java/com/github/ambry/store/LogSegmentTest.java