Something You Always Wanted to Know About Testing* *But Were Afraid to Ask

Jorge Juan Barroso Carmona

Android Expert

@flipper83 jorge@karumi.com

TESTS

What is Testing?

Checking is confirmation, verification, and validation. By machines.

Testing is exploration, discovery, investigation, and learning. By humans.

versus

Why Testing?

Martin Fowler

!

“ more Functionality more Quickly ”

“ Bad code affect to your Costumer ”

What are Unit Tests?

Black-Box before White-Box

creating tests in an environment where they have some Control over their own

Destiny.

Be careful, sometimes Context is Everything.

more Information in a test than in code. Paranoid?

Don’t create your own Problems.

Turn most unit tests into Assertions.

Don’t test Implementation Details.

“ Si tu Unit test tarda más de 1 segundo, cómprate un pony y no me vendas que eso es un Unit test ”

@Jordi9

Mock or Stub?

Stubs are canned answers to calls.

Mocks are objects pre-programmed with expectations.

Avoid creating methods only for stubs.

A Big dependency of Robolectric and PowerMock is a sign of bad code.

Mock dilema: your test only checks that your mocks works.

What are Integration Tests?

Don’t test all your Layers at the same time Or at least Be aware you are doing it

Duplicated tests.

Write O(n!) tests.

where “n” it’s the number of collaborators

Don’t test the System or External Libraries.

Sometimes is a Good practice to test all your layers.

Why you should use Continuous Integration

The best test is the one that is Never executed.

Increase your Time to develop.

Everyone has the latest executable and can see what’s happening.

“ automated crap is still crap. ”

James O Coplien

How to decide the Test Coverage?

Low level coverage says that the code is badly tested, but you cannot claim the opposite with just high level

coverage

100% coverage is to test all possible code paths. Is TDD here?

Tests are code, we need to maintain them.

Risk-based Testing: prioritize the test over the risk of failure, the importance and the impact of failure.

“ I get paid for code that works, not for tests, so my philosophy is to test as little as possible to

reach a given level of confidence ”

Kent Beck

“ In most businesses, the only tests that have business value are those that are derived from

business requirements. ”

James O Coplien

Recap

Silver bullets do not exist.

The really important thing is to write Faster and better code

And please, expose your Dependencies and write Readable code

your Code is more important that your tests.

“ If you find your testers splitting up functions to support the testing process, you’re destroying your system architecture and code comprehension along

with it. Test at a coarser level of granularity. ”

James O Coplien

+ James Bach and michael bolton. checking vs testing (2009 - 2013) + Workflows of Refactoring. martin fowler. (oop 2014) + Why Most Unit Testing is Waste. James O Coplien (2013) + 467 tests, 0 failures, 0 confidence. Katrina Owen (Railsberry 2013) + Mocks Aren't Stubs. martin fowler (2007) + Integrated Tests Are A Scam. J.B. Rainsberger (2013) + Exploratory and Risk Based Testing. Bach, J. Kaner, C. (2004) + Decomposing into modules. D.L. Parnas (1972) + The Art of Unit Testing. Roy Osherove + Test Driven Development: By Example. Kent Beck + UnitTest. Martin fowler 2014 !

References

Q&A?@flipper83 jorge@karumi.com