Testing Big Data application is more a verification of its data processing rather than testing the individual features of the software product. When it comes to Big data testing, performance and functional testing are the key.
In Big data testing QA engineers verify the successful processing of terabytes of data using commodity cluster and other supportive components. It demands a high level of testing skills as the processing is very fast. Processing may be of three types
Along with this, data quality is also an important factor in big data testing. Before testing the application, it is necessary to check the quality of data and should be considered as a part of database testing. It involves checking various characteristics like conformity, accuracy, duplication, consistency, validity, data completeness, etc.
The following figure gives a high level overview of phases in Testing Big Data Applications
Big Data Testing can be broadly divided into three steps
The first step of big data testing, also referred as pre-Hadoop stage involves process validation.
- Data from various source like RDBMS, weblogs, social media, etc. should be validated to make sure that correct data is pulled into system
- Comparing source data with the data pushed into the Hadoop system to make sure they match
- Verify the right data is extracted and loaded into the correct HDFS location
The second step is a validation of “MapReduce”. In this stage, the tester verifies the business logic validation on every node and then validating them after running against multiple nodes, ensuring that the
- Map Reduce process works correctly
- Data aggregation or segregation rules are implemented on the data
- Key value pairs are generated
- Validating the data after Map Reduce process
The final or third stage of Big Data testing is the output validation process. The output data files are generated and ready to be moved to an EDW (Enterprise Data Warehouse) or any other system based on the requirement.
Activities in third stage includes
- To check the transformation rules are correctly applied
- To check the data integrity and successful data load into the target system
- To check that there is no data corruption by comparing the target data with the HDFS file system data