Refactoring Legacy Code guided by Simple Design
summary
Walks a messy Java production module down to a safe-to-change shape by deleting dead code, moving constants into consumers, extracting methods, renaming for intent, and adding characterization tests that lock current behavior. Uses Eclipse shortcuts, UC Detector to find unused publics, Mockito for mocks, and EclEmma/Emma for coverage. Starts from a file util claimed at ~500,000 lines, spends about 1.5–2 hours of work, gets full coverage on the focal method, and checks incremental commits proving the refactor compiles and tests pass.
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chapters (15)
- 0:00Intro
- 1:25Code base overview
- 2:41Legacy codebase overview
- 6:09Find more dead code
- 7:02Delete unused methods
- 11:30Remove unneeded classes
- 16:42Rename vigorously
- 17:45Extract method
- 19:41Characterization tests
- 28:39Unit tests
- 31:01Extract code
- 33:26Illegal argument exception
- 33:59Job parameters
- 36:16Mocks
- 41:15Ifelse
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