How do you explore and understand complex software systems?

1 Start with high-level overview

Before diving into the details of a complex software system, it is helpful to get a high-level overview of its purpose, scope, and design. This can help you identify the main components, interfaces, and interactions of the system, as well as its key features, requirements, and risks. You can use various sources of information to get this overview, such as documentation, diagrams, user stories, stakeholder interviews, or even a demo of the system. Try to get a clear picture of the system's context, goals, and constraints, and how it fits into the bigger picture of the organization and the domain.

2 Use exploratory testing

Exploratory testing is a powerful technique for learning about a complex software system through experimentation and observation. It involves designing and executing tests based on your curiosity, intuition, and feedback, rather than following a predefined script or plan. Exploratory testing allows you to discover new aspects of the system, find hidden bugs, and generate new test ideas. You can use various tools and heuristics to support your exploratory testing, such as mind maps, checklists, models, oracles, or test charters. You can also collaborate with other testers or developers to share insights and learn from each other.

4 Trace the data flow

Another way to explore and understand a complex software system is to trace the data flow through the system. Data flow is the movement of data from one component or process to another, and it can reveal a lot about the logic, functionality, and performance of the system. You can use various techniques to trace the data flow, such as data flow diagrams, data mapping, data profiling, or data logging. You can also use test data to verify the data flow and check for data quality issues, such as inconsistency, incompleteness, or corruption.

5 Review the code

Reviewing the code of a complex software system can help you gain a deeper understanding of its structure, logic, and implementation. It can also help you identify potential defects, vulnerabilities, or code smells that might affect the quality or security of the system. You can use various tools and practices to review the code, such as code analysis tools, code review tools, code metrics, code standards, or code comments. You can also use code coverage tools to measure how much of the code is exercised by your tests, and where you might need to add more tests.

6 Ask questions

The last tip for exploring and understanding a complex software system is to ask questions. Questions are a powerful way to stimulate your curiosity, challenge your assumptions, and clarify your doubts. You can ask questions to yourself, to your peers, to your stakeholders, or to the system itself. You can use various types of questions, such as open-ended, closed-ended, probing, or hypothetical questions, depending on your purpose and context. You can also use question frameworks, such as the 5 Whys, the 5 Ws and 1 H, or the Socratic method, to guide your questioning process.