Spring GDS 25th Anniversary
A logistics company that ships to 190 countries built something to ship to itself.
Test coverage
What is test coverage?
Test coverage measures how much of your code gets executed when the test suite runs, usually as a percentage. Line coverage tracks which lines ran. Branch coverage tracks whether both sides of each if/else were taken. Function coverage tracks which functions were called at all. A tool instruments the code, runs the tests, and reports the share of it that the tests actually touched.
The number is useful and easy to misread. High coverage tells you tests run through most of the code. It does not tell you the tests check the right things. A test can execute a function, assert nothing meaningful, and still count toward 100% coverage. That's the trap: coverage measures execution, not correctness. A payment module at 95% coverage can still ship a bug if none of those tests verify the actual amount charged. Coverage shows you what was never tested at all, which is genuinely valuable, but a green number is a floor, not a guarantee.
Chasing 100% rarely pays. The last stretch often means writing tests for trivial getters and error branches that will never realistically fire, which costs time and adds noise. Most teams set a sensible threshold, watch for sudden drops that signal untested new code, and spend their real effort making sure the important paths have tests that assert something worth asserting.
Test coverage at Dallonses
We use coverage as a signal, never as a scoreboard. A coverage report is good at one thing: showing the code your tests have never touched. We read it that way, look at what's missing on the paths that carry real risk, and write tests that verify behavior rather than just walking the lines.
We won't chase a number for its own sake, and we'll say so to a client who asks for 100%. A suite gamed to hit a target looks reassuring and protects nothing. Our automated testing focuses coverage where failure would actually hurt, the money flows and the core logic, and keeps it honest with assertions that would genuinely fail if the code broke. The point of the report is fewer bugs in production, not a prettier dashboard.
Got a high coverage number you're not sure you can trust? Let's pressure-test it.
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