Working Effectively with Legacy Code (draft)

Working Effectively with Legacy Code written by Michael Feathers Something I understand about the book

Contents ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The Book ,[object Object],[object Object],http://www.amazon.com/Working-Effectively-Legacy-Michael-Feathers/dp/0131177052 Paperback: 456 pages Publisher: Prentice Hall PTR; 1 edition (October 2, 2004)

What is legacy code? (for me/us?) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

What is legacy code? (M.Feathers) ,[object Object],[object Object],[object Object]

The conservative approach ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],If it ain't broke don't fix it

Preserving Behaviour with Characterization Tests ,[object Object],[object Object],[object Object],Please note that: “actual” is not always the same as “correct”.

Characterization Tests Example (1/5) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Characterization Tests Example (2/5) ,[object Object],[object Object],[object Object],[object Object],Testcase: testSlaDjcl(prova.ProvaTest): FAILED array lengths differed, expected.length=0 actual.length=3 junit.framework.AssertionFailedError: array lengths differed, expected.length=0 actual.length=3 at prova.ProvaTest.testSlaDjcl(ProvaTest.java:19)

Characterization Tests Example (3/5) ,[object Object],[object Object],[object Object],[object Object],Testcase: testSlaDjcl(prova.ProvaTest): Caused an ERROR arrays first differed at element [0]; expected:<0> but was:<1858> arrays first differed at element [0]; expected:<0> but was:<1858> at prova.ProvaTest.testSlaDjcl(ProvaTest.java:19)

Characterization Tests Example (4/5) ,[object Object],[object Object],[object Object],[object Object],BUILD SUCCESSFUL (total time: 0 seconds)

Characterization Tests Example (5/5) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

The TDD algorithm ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Conclusions: Complaints / Solutions matrix So then you ... But legacy code… add them (as characterization tests) lacks of test redesign it (with refactoring) is ugly

Conclusions: I can’t put code under tests because So you I can’t because code ,[object Object],[object Object],depends of everything ,[object Object],[object Object],lacks of modularity

Thanks ,[object Object],[object Object],[object Object],[object Object],[object Object]

Working Effectively with Legacy Code (draft)

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