final FileInputSplit split = new FileInputSplit(0, new Path(this.file.toURI().toString()), 0,
this.file.length(), null);
when(this.environment.getInputSplitProvider()).thenReturn(this.inputSplitProvider);
when(this.inputSplitProvider.getNextInputSplit()).thenReturn(split, (FileInputSplit) null);
FileLineReader reader = new FileLineReader();
Whitebox.setInternalState(reader, "environment", this.environment);
Whitebox.setInternalState(reader, "output", this.recordWriter);
StringRecord record = mock(StringRecord.class);
whenNew(StringRecord.class).withNoArguments().thenReturn(record);
reader.invoke();
// verify the correct bytes have been written and read
verify(record, times(3)).set(in.getBytes());
}