Design Patterns · Middle · Question 69 of 75

How do you safely refactor legacy code without tests?

✓Correct answer: First write characterization tests that capture current behavior, then refactor in small steps
2Rewrite it from scratch
3Refactor and test manually afterwards

Explanation

Characterization tests lock in what the code does today (even bugs). Seams let you inject test doubles.

Further reading

Test yourself

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