What does an ETL tester do

Torsten Pohl

About me as an ETL tester

As a qualified computer scientist (FH), ISTQB certified tester and certified tester of data warehouse (DWH) and business intelligence systems (BI), I offer freelance services as an ETL tester.

As an ETL tester, I have specialized in the quality assurance of data models and mapping rules as well as in the testing of ETL processes in several projects in the banking sector.

I have strong communication skills and a lot of experience working with agile teams. I love getting to know new technologies and working with new teams all the time.

I also like to bring my extensive experience to your project - preferably in the Darmstadt, Frankfurt am Main, Aschaffenburg, Heidelberg, Mainz, Mannheim or Wiesbaden area. I will be happy to send you my qualification profile and references from my previous customers on request.

ETL testing tools

Test data generator for ETL tests

The market has many test data generators for names, addresses or credit card data. However, in order to generate test data for different equivalence classes and limit values ​​for each individual field with its corresponding data type for technical tests of ETL processes, I have developed a test data generator that analyzes a Data Definition Language (DDL) with CREATE-TABLE statements and creates a appropriate set of test data created as INSERT-INTO statements or tab-separated values.

The test data generator was developed as a web application and can generate test data for the data types of common database management systems (currently Oracle, DB2 and MySQL / MariaDB) without a local installation. Further database management systems and test data classes can basically be added.

The implemented test data classes for the data type VARCHAR are shown in the following list as an example:

  • Valid Value: Any string with a length between 1 and the maximum string length with characters that do not match spaces or the standard string (if available);
  • Minimum value: Explicit value “(empty string);
  • Maximum Value: Any string of maximum string length with characters other than spaces;
  • NULL: Explicit value NULL (if the particular column is nullable);
  • Special characters: Any character string with special characters (e.g. umlauts, diacritics);
  • Control characters: Any character string with control characters (e.g. tabulator, form feed, carriage return);
  • Spaces only: Any string that consists only of spaces;
  • Leading and trailing blanks: All substrings with characters that do not match the blanks and have leading and trailing blanks;
  • Escaping characters: Any string with escaping characters (e.g. quotation marks, single quotation marks, backslash);
  • Syntax-specific characters: Any character string with syntax-specific characters (e.g. for XML syntax: <,>, &, quotation marks, apostrophe);

Test automation framework for DWH tests

With the experience from my data warehouse projects, I have also developed a test automation framework for DWH testing with which ...

  • Test cases can be conveniently managed and versioned in the form of SQL statements and organized in test suites,
  • Test runs can be carried out for different test suites,
  • Test results and test protocols can be traced at any time for all test runs for all releases in all layers of all test environments and
  • Test results can be exported to other test management tools (currently TM4J and Xray for Jira).

The test automation framework can be used with common database management systems (currently Oracle, DB2 and MySQL / MariaDB), has an administration application for Windows, macOS and Linux with basic reporting and backup functions and can be used to export test results to other test management software and, in principle, can be adapted to other database management systems.

The test automation tool was developed explicitly for testing ETL processes, but can also be used for all other database tests in which a large number of test cases in the form of SQL statements with preconditions and postconditions have to be executed and evaluated.

The system can be used independently, but can also be integrated into continuous integration environments and expanded with custom reports with common business intelligence and reporting tools.

I am currently fully booked and will not be available for new projects until July 2021 at the earliest.
Do you have a specific question about my test data generator for ETL tests or my test automation framework for DWH tests? Then just ask me! Write me an email or leave a comment below this article.