Canary Tests

Canary Tests are minimal tests to quickly and automatically verify that everything you depend on is ready. You run Canary tests before other time-consuming tests, and before wasting time investigating in your code when the other tests are red. If the canary test fails, you know you have to fix something on the environments first.

This idea of Canary test is different from the Canary Deployment. In Canary Deployment you deploy to a small fraction of your users to check everything’s fine before rolling out to more users.
 
 20140120-2358251

Save time by checking what should be always OK

Canary tests check for the obvious and frequent sources of issues, such as:

  • connectivity to network: firewall rules ok, ports open, proxy working fine, NAT, ping below a good threshold
  • Databases and middleware are up
  • disk quota for logs not almost full
  • every needed login and password is valid
  • installed software available in the right version: dll installed, registry set-up, environment variables set, user directories all exist, the frameworks and OS versions are fit, timezone and locale are as expected
  • reference data integrity and consistency (dates, valuations…) are ok
  • Database schema and audit of applied scripts are as expected
  • Licences are not expired (there is usually a way to check that automatically)

Canary tests should run regularly, ideally before any expensive tests like end-to-end tests. Of course you want to run them whenever there is a trouble somewhere, before wasting time on manual investigations in your code when the expected environment is not fully available.

Even at the code level, a canary test is just a trivial test to verify that the testing framework works correctly, as mentioned by Marcus on his blog:

assertTrue(true)

Don’t forget to verify that your tests can fail too!

Simple and low-maintenance

The canary test tools should not assume much from the application. They must be independent from new developments to be as stable as possible. They should require little to no maintenance at all.

One way to do that in practice is to simply scan configuration files for every URL, password and just ping them one by one against a predefined time threshold. Any log path mentioned in the configuration files can be scanned and checked for the required write permissions and available disk space. Any login and password can be checked, even though this may be more complicated.

Canary tests are documentation too

Doing Canary tests may require explicit declarations of expectations, e.g. an annotation AssumedPermission(’777′) to declare the permissions required on the files referenced in the configuration files. Alternatively you may rely on a Convention Over Configuration principle. For example every

log.*.path

variable is assumed  to be a log path to check against some predefined expectations like being writable and being ok with disk quota.

When you add canary tests, this automation itself is a form of documentation that makes assumption more explicit.

You could export a report of every canary test that has been ran into a readable form that can become part of your Living Documentation.
 

Reference: Canary Tests from our JCG partner Cyrille Martraire at the Cyrille Martraire’s blog blog.
Related Whitepaper:

Software Architecture

This guide will introduce you to the world of Software Architecture!

This 162 page guide will cover topics within the field of software architecture including: software architecture as a solution balancing the concerns of different stakeholders, quality assurance, methods to describe and evaluate architectures, the influence of architecture on reuse, and the life cycle of a system and its architecture. This guide concludes with a comparison between the professions of software architect and software engineer.

Get it Now!  

Leave a Reply


two × = 12



Java Code Geeks and all content copyright © 2010-2014, Exelixis Media Ltd | Terms of Use
All trademarks and registered trademarks appearing on Java Code Geeks are the property of their respective owners.
Java is a trademark or registered trademark of Oracle Corporation in the United States and other countries.
Java Code Geeks is not connected to Oracle Corporation and is not sponsored by Oracle Corporation.

Sign up for our Newsletter

15,153 insiders are already enjoying weekly updates and complimentary whitepapers! Join them now to gain exclusive access to the latest news in the Java world, as well as insights about Android, Scala, Groovy and other related technologies.

As an extra bonus, by joining you will get our brand new e-books, published by Java Code Geeks and their JCG partners for your reading pleasure! Enter your info and stay on top of things,

  • Fresh trends
  • Cases and examples
  • Research and insights
  • Two complimentary e-books
Get tutored by the Geeks! JCG Academy is a fact... Join Now
Hello. Add your message here.