What Is Change Impact Analysis?
Change impact analysis is the practice of determining what else a proposed code change will affect before you make it — identifying the dependent code, tests, data and interfaces that could break.
What it involves
You identify the code being changed, then trace outward to everything that relies on it: calling functions, dependent modules, API consumers, database reads and writes, and the tests that cover any of them.
It is done most often before a refactor, before changing a shared interface or API, and before a data migration — the changes where the cost of a missed dependency is highest.
Manual versus graph-based
Done by hand, it depends on someone remembering every caller. Done from a dependency graph, it is exhaustive: the graph already records every import and call, so the affected set can be computed rather than recalled.
The output is used to scope code review, size the work, and decide how much testing a change needs.
Common questions
What is change impact analysis?
It is the practice of determining, before making a code change, what else that change will affect — dependent code, tests, data and interfaces that could break as a result.
How do you perform impact analysis on a code change?
Identify the code you will change, then use the dependency graph to find every module, caller, API consumer and test that depends on it, directly or transitively.
What is the difference between impact analysis and a dependency graph?
The dependency graph is the data — what depends on what. Impact analysis is what you do with it: reading the graph outward from a planned change to find everything at risk.
Related
- Change impact analysis tool — Map the exact blast radius of any code change before you ship. Plain-English change impact analysis, traced through your real dependency graph. Try it free.
- Blast radius (in code) — glossary
- Dependency graph — glossary
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