testing with mock objects

when i say testing… == developer / unit tests == integration tests (sometimes) != functional / acceptance tests

== developer / unit tests

== integration tests (sometimes)

!= functional / acceptance tests

when i say mock… test stub mock object dummy object fake object

test stub

mock object

dummy object

fake object

mock vs. stub interaction vs. state the difference between mocks and stubs usually the same library provides both interaction = mock state = stub

the difference between mocks and stubs

usually the same library provides both

interaction = mock

state = stub

why?

testing is easy in isolation

testing is harder with dependencies …

… so remove the dependencies (for developer testing)

for me… lots of time in the airport lots of time in the airplane lots of time on the train not enough family time not enough snowboarding

lots of time in the airport

lots of time in the airplane

lots of time on the train

not enough family time

not enough snowboarding

scenarios to think about fee per transaction distributed development parallel development plug-ins / providers automated test duration

fee per transaction

distributed development

parallel development

plug-ins / providers

automated test duration

scenarios to think about third-party tools or services non-deterministic outcomes external systems the mainframe crew defer infrastructure choices

third-party tools or services

non-deterministic outcomes

external systems

the mainframe crew

defer infrastructure choices

demo

thoughts

… on architecture and design similar to the benefits of tdd writing to interfaces = code empathy easier to test = good design highly cohesive / loosely coupled

similar to the benefits of tdd

writing to interfaces = code empathy

easier to test = good design

highly cohesive / loosely coupled

… on implementation good libraries exist roll your own only for extreme cases for .Net… NMock, NMock2, Rhino Mocks, DotNetMock

good libraries exist

roll your own only for extreme cases

for .Net…

NMock, NMock2, Rhino Mocks, DotNetMock

… on automated builds developer tests: use mocks (if necessary) acceptance tests: don’t use mocks

developer tests: use mocks (if necessary)

acceptance tests: don’t use mocks

… on a few useful patterns code to interfaces thin proxies self-shunt dependency injection providers

code to interfaces

thin proxies

self-shunt

dependency injection

providers

learn more

http:// www.martinfowler.com/articles/mocksArentStubs.html

http:// xunitpatterns.com /

http:// www.nmock.org

http:// www.mockobjects.com

http:// www.codeproject.com/dotnet/tdd_in_dotnet.asp