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TDD and Code Coverage

publish date: 2026/06/18 05:45:5.795482 UTC

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One of the benefits of TDD is that it leads to high code coverage. Why does TDD help achieve comprehensive code coverage?

Every code increment written in TDD has at least one associated test, so all code that is added is tested

Coverage is automatically guaranteed because TDD uses formal verification methods

TDD enforces 100% branch coverage through mandatory path analysis before coding begins

TDD requires that coverage tools be run after every commit to the repository

Correct Answer

Every code increment written in TDD has at least one associated test, so all code that is added is tested

Explanation

TDD leads to high code coverage because every piece of code is written to make a specific failing test pass. Every code increment has at least one associated test. In principle, all code that is added to a system is exercised by at least one test - which is a much stronger coverage guarantee than writing tests after the code.

Reference

Software Engineering, Ian Sommerville, 10th edition

Quizzes you can take where this question appears

Test-Driven Development - Process and Benefits