retro testing (devcontlv jan 2014)

1Allon Mureinik - Retro Testing

Retro Testing

Allon MureinikTeam Lead, Cloud Storage, Red Hatamureini@redhat.com / @mureinik

January 2014

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TDD Is Easy...

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... or is it?

● The first two part should be● Write a test● Make sure it fails

● The question is why it fails.

● In a legacy system, it will often fail for “bad” reasons:● Unable to access the database● Some static resource not set up● Need to spin up an application server● Etc., etc., etc...

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Will the mistakes of the past haunt me forever?

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It’s not an all-or-nothing situation

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One baby step at a time

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Refactor, refactor, refactor

● Your first task would probably be to do some refactoring

● Resist the urge to improve the code● Frankly, this step may make the code look worse

● Your only goal here is to create an opportunity to write tests

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Refacroting with no tests is like...

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Example : Bad Code

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Some minimal refactoring

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Now we can start writing tests...

● Now we have the tools to separate external resources from logic

● There are a couple of ways to do so:● Override the relevant methods in your test● Use Mockito/EasyMock to spy the tested object● Use @Rules to set up common mocking once

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I @Spy With My Little Eye

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Some more refactoring

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Let’s modernize our code

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But how can I write asserts?

● Overriding, mocking and all that jazz are fine and well

● But any test boils down to writing an assert...

● ... and I have no idea what this function is supposed to do

● Remember this is a legacy system

● You may not need to test it for correctness ...

● Just for backwards compatibility

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The real challenge is changing mindset

● We can discusses refactoring till we’re blue in the face

● But the real challenge isn’t changing the way we code

● It’s changing the way we approach the problem

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It’s all too easy to slip back to bad habits

● This bug is blocking the release...

● It’s a ton of work to refactor this logic out...

● The rest of the code is bad anyway...

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Have the courage to stand up to excuses

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Questions?