OSGi Versioning & Testing

Chris Aniszczyk EclipseSource http://aniszczyk.org Paul VanderLei Band XI International

T elematics - O n- A - ST ick Sample from upcoming book equinoxosgi.org Example project in EclipseRT wiki.eclipse.org/Toast OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

“ Software versioning is the process of assigning either unique version names or unique version numbers to unique states of computer software.” Versioning is relative though… OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

Versioning is a marketing thing… User’s don’t really care about versions… Users just want to know if the version of the software they are running is current… e.g., Ubuntu Feisty Fawn – 7.04 Gutsy Gibbon – 7.10 Hardy Heron – 8.04 OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

Version numbers are like dog tags * Primarily used in an event of emergency… OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0 * http://www.codinghorror.com/blog/archives/000793.html

Dependencies are defined on the module and package level Import-Package Require-Bundle Ranges allow for flexibility Import-Package: org.easymock;version=[2.4.0,3.0.0) OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

major.minor.micro.qualifier major – An incompatible update; breaking API minor – A backward compatible update; API stable micro – A bug fix; no API changes qualifier – build date; lexigraphic Versions should encode compatibility* at the bundle and package level OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0 *http://wiki.eclipse.org/Version_Numbering

Managing versions is important and painful At Eclipse, we learned this lesson and have many experiences in dealing with maintaining and evolving API Other projects eventually learn the importance of versioning… OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0 “ I still believe a an official compatibility statement are in order. It includes a definition of the API and a separate definition of the SPI, and possible a third definition of the Configuration. I bet everyone would back such statement, would clarify the "unbreakable“ parts, and what is "features of your own risk" and so on.”

OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0 http://commons.apache.org/collections/compatibility.html “ Commons collections 3.0 is binary compatible with version 2.1 and 2.0 except for certain methods on one class. As the release was a major version, this is permitted, however it was unintentional and an error … the chosen solution is to provide a work around by releasing v2.1.1 and v3.1.”

Users need to understand the contract when using your software… Good fences make for good neighbors! Binary compatibility is important OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

Binary compatibility is important Maintaining binary compatibility is complex Eclipse puts API on an altar… Since Eclipse 3.4, Eclipse uses tools to manage and evolve API… OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0 *http://java.sun.com/docs/books/jls/second_edition/html/binaryComp.doc.html

Assists developers in API maintenance by reporting API defects such as binary incompatibilities, incorrect bundle version numbers and API usage. Let’s revisit the GPS example… OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

Getting proper version ranges correct is difficult if there’s no consistent semantics e.g., log4j case… [1.2.0,1.3.0) or [1.2.0,2.0.0) ? Not all bundles are versioned properly in repositories Tooling doesn’t cover packages yet… OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

OSGi versions encode compatibility! Don’t treat bundle versions like a marketing number Scope your version ranges properly OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

Write your application as POJOs (plain-old-java-objects) No Service Trackers! Whiteboard Pattern is tricky Pay attention to dependencies Unit testing depends on getting this right OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

Use Junit Use mock objects (EasyMock, jMock...) Minimize delays No human interaction Do TDD OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0 “… I think that developers who can’t cope with any level of TDD shouldn’t be coding at all…”

Terminology Unit under test (UUT) Test harness Test each POJO on its own (no OSGi) Mock each dependency OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0 get location Log Emergency Servlet GPS Channel Airbag Mock GPS Mock Channel Emergency Monitor Mock Airbag

Test as much of system as possible OSGi is present Test full system flow Test bundles coming and going OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

log get location OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0 deploy Log Mock Log Emergency Servlet Channel GPS Emergency Monitor Airbag Mock Airbag Test Case

PDE Junit test infrastructure uses Equinox extensions Declarative Services uses OSGi services OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

Junit instantiates the test case as usual setup() testEmergency() Problem: no way to obtain: bundle context mock airbag mock log OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

Instantiates the test case as a component DS dependency injection setAirbag(<our mock airbag>) setLog(<our mock log>) startup() Problem: This instance is never used by Junit! OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

Get the slides: tinyurl.com/osgiVT Get the code: wiki.eclipse.org/Toast Get the book: equinoxosgi.org OSGi Versioning and Testing | © Copyright 2009 EclipseSource & Band XI International; made available under EPL v1.0

OSGi Versioning & Testing

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