Source: Adapted from Agile Data Warehousing for the Enterprise, 2016, Ralph Hughes

The value of for DWH/  

Shifting quality assurance left basically means DWH/BI teams are catching bugs earlier in the process. Spending weeks or months at the end of a release cycle finding and fixing issues is inefficient—and it’ll cost you. An IBM study found that “it is 100 times more expensive to fix a defect that is found after it has been released.” That math should get most teams behind automated testing.

“The primary way you can get users what they need and what the company expects is to be testing where we’ve written, built and deployed code,” Titus Fortner of Sauce Labs has said. “Making sure you have the right tests in the right place to get rapid feedback. That’s where I see things needing to be in the industry.”

When Shift Left practices are implemented in the DWH/BI SDLC, the software system testing activities take place much earlier in software development life cycle. The goal is to fix looming issues that might crop up in the future and therefore meet the marks of quality in delivery. So when organizations adopt the Shift Left strategy, they are able to test, analyze projects, pass judgment on the system and refine it into something much better bit-by-bit.

How to begin Shift Left testing on DWH/BI projects

Pick one small team, and have a tester work with other team members on a feature from the very beginning. This should include everyone from the product manager, to business analysts, to programmers. It is important to create test automation assets because they assure rigid governance across the entire end-to-end testing process.  The entire team attends meetings together, reviews code together, tests together, and decides when requirements are complete.

Among the most critical components of your Shift left efforts should be the automated testing tools your team adopts. Testing earlier and faster is nearly impossible without automation. Depending on how far along you are in your DevOps or agile journey, you may already have an entire network of continuous integration and delivery tools. You may want to extend it with, for example, test automation that supports testing:  column profiling, model-based testing,  support for regression and reconciliation testing, business rules/transformations testing and BI report verifications.

Ideas for automating Shift Left tests for DWH/BI

Shifting left enables test automation. By testing earlier, teams can automate test cases earlier and reuse the automated test cases. It is good practice to execute test cases before automating them in order to make sure the test case runs smoothly when automated.

Vital check testing is one valuable way to expose data acquisition (ETL) errors early in the process. You can automatically generate vital checks for both data quality and data processing. The following test types can be easily created with automated BI/Data Warehouse testing tools:

  • Pre-screening tests: Verify source data for missing values, duplicates, data formats etc.
  • Metadata tests: Check whether table and column information has changed during loads
  • Completeness tests: Enable count comparisons between sources and targets
  • Uniqueness tests: Check for the uniqueness constraint defined files or tables
  • Referential integrity tests: Check that complete records have been copied and that technical as well as logical integrity is maintained
  • Data reconciliation tests: Perform complete source-to-target comparison—including file-to-database and database-to file comparisons

Concluding Remarks

If the idea takes hold, Shift Left testing will ensure that business analysts and developers, in particular,  take on additional testing tasks. Most already conduct comprehensive unit testing, making sure that small increments of code work even as they write them. This Agile practice is important because it incorporates testing early in the development cycle. It also emphasizes that testing is an integral part of software development and everyone is responsible for quality and success.

Encouraging developers to write reusable test scripts is one of many positive outcomes of the Shift Left movement. As developers continuously add and change code, their unit test scripts drive valuable regression tests that expose fundamental implementation issues early. This, in turn, frees QA to focus on completing higher-level testing, where they can identify integration and system-level issues.

Shifting tests left often encourages and enables early automation. By testing earlier, teams can maximize their ROI on test automation while exposing errors when they are fastest, easiest, and cheapest to fix.

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