@Override
    public void open(FileInputSplit split) throws IOException {
        super.open(split);
        initBuffers();

        this.offset = splitStart;
        if (this.splitStart != 0) {
            this.stream.seek(offset);
            readLine();
            // if the first partial record already pushes the stream over
            // the limit of our split, then no record starts within this split
            if (this.overLimit) {
                this.end = true;
            }
        } else {
            fillBuffer(0);
        }
        initializeSplit(split, null);
    }
@Test
    void testOpen() throws IOException {
        final String myString = "my mocked line 1\nmy mocked line 2\n";
        final FileInputSplit split = createTempFile(myString);

        int bufferSize = 5;
        format.setBufferSize(bufferSize);
        format.open(split);
        assertThat(format.splitStart).isZero();
        assertThat(format.splitLength).isEqualTo(myString.length() - bufferSize);
        assertThat(format.getBufferSize()).isEqualTo(bufferSize);
    }