Requirements engineering like testing require balance of value and risk. Agile requirements engineering and testing with test-driven requirements engineering (TDRE) balances project risks and cost. Clear advantage: Requirements are understandable, testable, and directly applicable as test case. Lead time and costs in testing are reduced by up to thirty percent.

This presentation at OOP 2023 will practically introduce to agile requirements engineering and test with TDRE. A case study demonstrates an industry use of TDRE.

Target Audience: Project Managers, Architects, Analysts, Requirements Engineers, Product Owners, Software Engineers
Prerequisites: None
Level: Advanced

Extended Abstract:
Requirements engineering like testing require balance. Balance is about balancing value and risk. Requirements must be good enough to mitigate risks but yet not overly specific to contain effort. Same for test, which though never complete needs to address those areas with highest risk.

Requirements engineering and testing belong together. Historically, testers have often only seen the requirements after the system has already been partially implemented. This had two serious disadvantages. On the one hand, insufficient requirements quality came far too late to the table. On the other hand, it was quite a lot of extra work without deriving suitable test cases in the context of requirements definition. A lot of additional work and long correction loops were the result.

Only an agile balance of risk-oriented coverage and testable requirements can improve test effectiveness. Such risk-oriented work also optimizes requirements engineering. Instead of paralysis by analysis in defining numerous requirements, test-driven requirements engineering (TDRE) focusses on specifying what is necessary and of high risk or high value.

TDRE is straight-forward: Test cases are developed in parallel to the requirements. Thus, the feasibility of the requirements is analyzed much faster than in the traditional sequential approach, in which tests are specified relatively late. The test cases are initially described in the same structure as the requirements and as a supplement to the respective requirements. This shifts Test-Driven Development (TDD), which has already proven itself as relevant agile methodology, to the specification level. Regression tests are attributed in order to prepare for later automation. The effort required for testing can be better estimated on this basis, and project and quality risks are thus reduced.
TDRE follows a triple peak model, which is connecting requirements (i.e., needs), design (i.e., solution) and test (i.e., the product).

It intertwines three perspectives:
•    Market perspective: “How can I meet customer satisfaction and needs?”
•    Design perspective: “How can I implement the solution to meet requirements?”
•    Testing perspective: “How can I find a defect and cause the product to fail?”

Here some guidance from our projects, which we will further illustrate in this presentation:
•    Every single functional requirement has at least one acceptance check, which is either fulfilled or not fulfilled and serves as the agile DoD (definition of done).
•    Each individual quality requirement is described with numerical values that can be measured.
•    Business rules are defined so that it can be determined whether they are true or false.
•    Business and data objects are defined with all their attributes, types and states so that they can be set and validated at test time.
•    System interfaces such as GUIs, reports and service interfaces are included in the requirements document so that values can be assigned to them.
•    All use cases have pre- and post-conditions that can be generated and validated.
•    All text is marked so that it can be automatically processed to generate test cases.

Agile requirements engineering and testing with test-driven requirements engineering (TDRE) balances project risks and cost. Clear advantage: Requirements are understandable, testable, and directly applicable as test case. Lead time and costs in testing are reduced by up to thirty percent. This presentation at OOP 2023 will practically introduce to agile requirements engineering and test with TDRE. A case study from medical cybersecurity demonstrates an industry use of TDRE.