Testing untestable code - STPCon11

Testing untestable code Stephan Hochdörfer, bitExpert AG

Testing untestable code About me  Stephan Hochdörfer, bitExpert AG  Department Manager Research Labs  S.Hochdoerfer@bitExpert.de  @shochdoerfer

Testing untestable code No excuse for writing bad code!

Testing untestable code Not to freak out!

Testing untestable code Creativity matters!

Testing untestable code "There is no secret to writing tests, there are only secrets to write testable code!" Miško Hevery

Testing untestable code What is „untestable code“?

Testing untestable code Wrong object construction “new” is evil! s

Testing untestable code Tight coupling

Testing untestable code Uncertainty

Testing untestable code "...our test strategy requires us to have more control [...] of the sut." Gerard Meszaros, xUnit Test Patterns: Refactoring Test Code

Testing untestable code In a perfect world... Unittest Unittest SUT SUT

Testing untestable code Legacy code is not perfect... Dependency Dependency Unittest Unittest SUT SUT Dependency Dependency

Testing untestable code ... Legacy code is not perfect... Dependency Dependency Unittest Unittest SUT SUT Dependency Dependency ...

Testing untestable code How to get „testable“ code?

Testing untestable code How to get „testable“ code? Refactoring

Testing untestable code "Before you start refactoring, check that you have a solid suite of tests." Martin Fowler, Refactoring

Testing untestable code Hope? - Nope...

Testing untestable code Which path to take?

Testing untestable code Which path to take? Do not change existing code!

Testing untestable code Examples Object construction External resources Language issues

Testing untestable code Object construction public class Car { private Engine engine; public Car(String engine) { this.engine = EngineFactory.getByType(engine); } }

Testing untestable code Object construction - Solution public class MyLoader extends ClassLoader { protected Class findClass(String name) throws ClassNotFoundException { try { String path = name.replace(., /); // @TODO: change path and read file, // @TODO: define package // @TODO: define class } catch(Exception e){ throw new ClassNotFoundException(name); } } }

Testing untestable code Object construction - Solution II <?php class MyStreamWrapper { private $_handler; function stream_open($path, $mode, $options, &$opened_path) { stream_wrapper_restore(file); // @TODO: modify $path before fopen $this->_handler = fopen($path, $mode); stream_wrapper_unregister(file); stream_wrapper_register(file, MyStreamWrapper); return true; } }

Testing untestable code External resources

Testing untestable code External resources Database Webservice Filesystem Mailserver

Testing untestable code External resources – Mock database

Testing untestable code External resources – Mock database Provide own db driver

Testing untestable code External resources – Mock database junit + dbunit

Testing untestable code External resources – Mock database Proxy for your SQL Server

Testing untestable code External resources – Mock webservice

Testing untestable code External resources – Mock webservice Provide own implementation

Testing untestable code External resources – Mock webservice Do not forget! Url redirection via /etc/hosts

Testing untestable code External resources – Mock filesystem

Testing untestable code External resources – Mock filesystem Commons-VFS vfsStream

Testing untestable code External resources – Mock filesystem <?php // set up test environmemt vfsStream::setup(exampleDir); // create directory in test enviroment mkdir(vfsStream::url(exampleDir)./sample/); // check if directory was created echo vfsStreamWrapper::getRoot()->hasChild(sample);

Testing untestable code External resources – Mock Mailserver

Testing untestable code External resources – Mock Mailserver Use fake mail server

Testing untestable code Dealing with language issues

Testing untestable code Dealing with language issues Testing your privates?

Testing untestable code Dealing with language issues final Method methods[] = o.getClass().getDeclaredMethods(); for (int i = 0; i < methods.length; ++i) { if (methodName.equals(methods[i].getName())) { try { methods[i].setAccessible(true); return methods[i].invoke(o, params); } catch (IllegalAccessException ex) { } catch (InvocationTargetException ite) { } } return null; }

Testing untestable code Dealing with language issues Overwrite internal functions?

Testing untestable code What else?

Testing untestable code What else? Generative Programming

Testing untestable code Generative Programming Configuration Configuration 1 ... n Implementation Implementation Generator Generator Product components components Product Generator Generator application application

Testing untestable code Generative Programming Configuration Configuration Application Application Implementation Implementation Generator Generator components components Testcases Testcases Generator Generator application application

Testing untestable code Generative Programming A frame is a data structure for representing knowledge.

Testing untestable code A Frame instance public class Car { private Engine engine; public Car(String engine) { this.engine = <!{Factory}!>.getByType(engine); } }

Testing untestable code The Frame controller public class MyFrameController extends SimpleFrameController { public void execute(Frame frame, FeatureConfig config) { if(config.hasFeature("unittest")) { frame.setSlot("Factory", "FactoryMock"); } else { frame.setSlot("Factory", "EngineFactory"); } } }

Testing untestable code Generated result - Testcase public class Car { private Engine engine; public Car(String engine) { this.engine = FactoryMock.getByType(engine); } }

Testing untestable code Generated result - Application public class Car { private Engine engine; public Car(String engine) { this.engine = EngineFactory.getByType(engine); } }

Testing untestable code What is possible?

Testing untestable code What is possible? Show / hide parts of the code

Testing untestable code What is possible? Change content of global vars!

Testing untestable code What is possible? Define pre- or postfixes!

Testing untestable code Is it worth it?

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Testing untestable code - STPCon11

by Stephan Hochdörfer on Mar 24, 2011

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Testing untestable code - STPCon11 Presentation Transcript