Hi Akhilesh,
For such type of example... it is expected that after designing ETL job, you provide possible combinations of input file with varying data and data type and check the proper working of the job... if it passes all the test cases, then it means that your ETL design is working fine... for any use case if your job fails, this indicates that you need improvement in the job...
This TDD is not like java programming code testing...
Vaibhav