Blog6-Blismos’ four-dimensional approach for comprehensive Big Data-ETL testing


Blismos’ four-dimensional approach for comprehensive Big Data-ETL testing can save costs by up to 75%

In today’s data-driven business environment, Big Data ETL testing is crucial for ensuring the accuracy of data, which is fundamental for making informed decisions.

At Blismos, we adhere to the highest standards of accuracy, consistency, and integrity in our ETL testing process. We have devised a Big Data – ETL Testing approach considering important dimensions – Planning and Process, Stages of Testing, Test data strategy and Automation. Our comprehensive approach gives our clients the confidence to rely on their data for informed decision-making and business success. Let’s take a closer look at each dimension

Planning & Process:

Successful ETL testing starts with a well-structured plan. This plan defines the scope, objectives, and success criteria for testing. A rigorous examination of every aspect of the ETL pipeline, from data extraction to transformation and loading, helps identify and mitigate potential issues, ensuring data accuracy and consistency.

Stages of Testing:

Application data testing is dedicated to the thorough examination of data transformations, ensuring that data is processed accurately according to predefined business rules. It focuses on validating data consistency, correctness, and accuracy within the context of the application’s functionality.

Ingestion testing focuses on verifying and validating the accuracy of data collection from heterogeneous source systems, ensuring that data is extracted correctly and reliably.

Data migration testing evaluates the process of transferring data between source and destination systems. It ensures data integrity during the migration process and validates data mapping and transformation accuracy during data transfer.

Data warehouse testing involves the validation of data loading into the data warehouse or data repository. This tests the accuracy of data transformations performed within the data warehouse and assesses data querying and reporting functionality.

Report testing: In ETL report testing, we carefully examine reports to confirm they accurately represent transformed data, maintain a user-friendly appearance, perform efficiently, seamlessly integrate with ETL processes, accommodate customization, uphold data security, and ensure their reliability remains robust during changes in the ETL environment, ensuring that these reports remain trustworthy resources for informed decision-making.

Test Data Strategy:

In the initial phases of ETL testing, it is vital to determine how to select the appropriate data for testing, encompassing the approach, criteria, and methods. Additionally, it is essential to consider the project’s requirements, the volume and characteristics of the data and to ensure the impartiality of our data sampling process.

Key components of a Test Data Strategy encompass Data Profiling, Data Volume, Data Variability, Sampling, Data Reconciliation, Data Privacy and Security, and Data Environment. We will delve into each of these aspects in a separate blog.


ETL testing automation entails the use of automated tools and scripts to conduct ETL tests with precision and efficiency. Automation accelerates the testing process, reduces the risk of manual errors, and provides detailed reports on test execution. We assess the feasibility of automation at various stages and develop a tailored automation strategy for each client project.

Automation across ETL Testing Stages

Planning Stage:

In the planning stage, automation aids in the scheduling and management of test execution. Automation tools can generate test schedules, allocate resources, and provide notifications for test planning activities.

Design Stage:

Automation during the design stage involves the generation of test scenarios, test case templates, and test data based on ETL process specifications. It streamlines the initial setup of test cases, ensures consistency in test case creation, and provides the necessary test data for comprehensive testing.

Execution Stage:

Automation in the execution stage takes center stage by automating the actual execution of test cases. It involves the use of automated testing tools to execute test scenarios, validate data transformations, and compare results against expected outcomes. Continuous testing through automation ensures data quality is maintained as ETL processes evolve, allowing for early detection of issues.