Refactoring Unit Tests

Anyone who wants to change existing code must also understand the associated tests. This brief presentation shows how comprehensible JUnit tests can look like: Existing unit tests are refactored using descriptive names, BDD structures and speaking assertions. JUnit 4, AssertJ and Awaitility are used.

Transcript

1. .consulting .solutions .partnership
   Refactoring Unit Tests
   Alexander Schwartz, Principal IT Consultant
   JUG Darmstadt / 7. December 2017
   

   View Slide

2. Demo
   © msg | Dezember 2017 | Refactoring Unit Tests | Alexander Schwartz 2
   

   View Slide

3. Summary
   © msg | Dezember 2017 | Refactoring Unit Tests | Alexander Schwartz 3
   Ideas:
   • Consider tests to check for features, not (only) classes
   • Introduce test methods with “should” to describe expected behavior
   • Add a “when” to describe conditions for a test
   • Use underscores to make the methods readable. Use capital letters and even Umlauts!
   • Break down the test in given/when/then
   • Try out AssertJ matchers for readability and fluent API
   • Use Awaitility for fast execution and avoid fixed sleep in execution
   Benefits:
   • When a test fails you can read up about the requirements in the code
   • Tests can be linked to business requirements and/or acceptance criteria
   • Test scope (what to test) and test steps (how to test) can be discussed with business owners
   

   View Slide

4. Links
   © msg | Dezember 2017 | Refactoring Unit Tests | Alexander Schwartz 4
   JUnit
   http://junit.org
   AssertJ
   http://joel-costigliola.github.io/assertj/
   Awaitility
   https://github.com/awaitility/awaitility
   Samples of today’s demo
   https://github.com/ahus1/bdd-examples
   @ahus1de
   Other libraries (not shown today)
   JGiven
   http://jgiven.org/
   JUnit Dataprovider
   https://github.com/TNG/junit-dataprovider
   Mockito
   http://site.mockito.org/
   

   View Slide

5. .consulting .solutions .partnership
   Alexander Schwartz
   Principal IT Consultant
   +49 171 5625767
   alexander.schwartz@msg-systems.com
   @ahus1de
   msg systems ag (Headquarters)
   Robert-Buerkle-Str. 1, 85737 Ismaning
   Germany
   www.msg-systems.com
   

   View Slide