Skip to main content

Testing Private

Image
By
A friend and former colleague of mine, Chris 'Frankie' Salt, recently popped up on Facebook messenger and asked me a question:

“I wonder if you'd mind answering a Java question for me? It's more of a best practices thing. So, encapsulation vs availability of methods for testing. Splitting your code into functions makes it a lot more readable and it makes sense to make these private as they will only ever be used once. However unit testing demands access to these private methods, I know there are ways around this but I was interested in your opinion.”

Me? Have an opinion about unit testing? Many stranger things have happened!

Encapsulation is all about hiding code away so that you can change it with minimal or no impact on other parts of the code base which use it indirectly. You shouldn't (ever) compromise encapsulation for the sake of testing. Every private method you write must be callable from at least one public method or via a chain of other private methods which is ultimately called from a public method. Otherwise, reflection shenanigans aside, it would never get called at all.

Does that mean reflection is the solution to testing private methods? No. It's a great tool for poking values into objects which are initialised using reflection at runtime, so that you don't have to add a public non-default constructor or public setters, but beyond that it should be avoided for testing.

Two solutions sprang to mind, triangulation and sprout classes. Read more.

Comments

Post a Comment

Popular posts from this blog

Catalina-Ant for Tomcat 7

By
I recently upgraded from Tomcat 6 to Tomcat 7 and all of my Ant deployment scripts stopped working. I eventually worked out why and made the necessary changes, but there doesn’t seem to be a complete description of how to use Catalina-Ant for Tomcat 7 on the web so I thought I'd write one. To start with, make sure Tomcat manager is configured for use by Catalina-Ant. Make sure that manager-script is included in the roles for one of the users in TOMCAT_HOME/conf/tomcat-users.xml . For example: <tomcat-users> <user name="admin" password="s3cr£t" roles="manager-gui, manager-script "/> </tomcat-users> Catalina-Ant for Tomcat 6 was encapsulated within a single JAR file. Catalina-Ant for Tomcat 7 requires four JAR files. One from TOMCAT_HOME/bin : tomcat-juli.jar and three from TOMCAT_HOME/lib: catalina-ant.jar tomcat-coyote.jar tomcat-util.jar There are at least three ways of making the JARs available to Ant: Copy the JARs into th...
22 comments
Read more

Write Your Own Load Balancer: A worked Example

By
I was out walking with a techie friend of mine I’d not seen for a while and he asked me if I’d written anything recently. I hadn’t, other than an article on data sharing a few months before and I realised I was missing it. Well, not the writing itself, but the end result. In the last few weeks, another friend of mine, John Cricket , has been setting weekly code challenges via linkedin and his new website, https://codingchallenges.fyi/ . They were all quite interesting, but one in particular on writing load balancers appealed, so I thought I’d kill two birds with one stone and write up a worked example. You’ll find my worked example below. The challenge itself is italics and voice is that of John Crickets. The Coding Challenge https://codingchallenges.fyi/challenges/challenge-load-balancer/ Write Your Own Load Balancer This challenge is to build your own application layer load balancer. A load balancer sits in front of a group of servers and routes client requests across all of the serv...
Post a Comment
Read more

Do software engineering professionals still read? - survey results

By
  In order to gauge the potential audience for my book, So you think you can lead a team? , I conducted a small survey of my colleagues, co-workers and anyone from Linked. I read regularly, for work and pleasure, and assumed everyone else did too but did the responses I received confirm this? I polled 173 people, all within the software engineering field (including Product, etc), with a range of ages and years of experience in their role. What surprised me the most was that the majority of people, young or old, just starting or seasoned, still prefer reading physical books to blogs or e-readers. It also seemed that the older and more experienced were the most keen in learning more, and reading to expand or update their knowledge.  When it comes to reading habits between different roles the survey showed that software engineers and team leads read more regularly for their career than other roles, with 55 years old and over and 16+ years experience being the biggest readers over...
3 comments
Read more