Ten deploys a day was the tech talk that started DevOps as an integrated practice for software development. However, if they simply pushed out code without checking it, then the story would have been different. Without testing the code, it would be more like 10 or more Disasters a day… A down production site would result in some serious consequences such as:
- Loss of customers
- Loss of confidence in the company
- Loss of employment for all who are involved
You get the pictures. Though the use of automation is a key principle of DevOps, automation is also an efficient way to multiply human error. Without efficient testing of code, CICD would be meaningless. If you write code quickly and deploy it, BUT it’s broken code, well you defeated the purpose of having software rapidly deployed and updated. Testing of code is one of the most fundamental part of DevOps there is.
But I’m a great coder and I don’t make mistakes…(or whatever is your excuse)
Well, that may be the case, however as your software product grows and more people are touching a code, the likelyhood some form of human error (that may not be yours) will be introduced into the code. It’s bad enough when you haven’t worked on the code let’s say in a couple of weeks, you don’t remember what you did. You don’t want to be called back into work on a Friday because your code changes you created bombs out on a production system… Test for it so you can sleep soundly knowing that you have a safety net in place.
Writing tests is a fundamental practice.
The fundamentals – Vince Lombarti, who is know as the winningest coaches in football once went to the lockerroom of his players after they had a major loss from a previous season and said .“..This is a football…” Part of writing good code is writing checks or tests for your code. Unfortunately, many programmers don’t write tests for their code, especially web developers who are use to just writing and fixing it as it breaks. It has been my experience that the reason many programmers don’t test code is quite simply, they don’t know how. We’ll get you pointed the right direction.
What are the various test you can do for code?
There are hundreds of different tests you can do on software, some are appropriate and some are not appropriate for testing your software. Here are a list of some of the more common tests. For the purpose of testing in a DevOps environment, there are basically two categories of test you can do for code. I’ll put particular emphasis on what are the must have tests. We’ll cover the must have tests. We’ll touch on the other tests.
These are the most basic test we need to have in place for Continuous Integration.
- Unit testing
- Integration testing
- Systems testing
- Acceptance testing
Non Functional Tests
These are also important tests but are not functional test (testing key functions in software) to have AFTER you have the core functional test in place. Here are a few non functional tests.
- Security testing – find security holes and exploits in your code.
- Performance testing – find out how quickly your code runs.
- Stress testing – find out how much load your application can take before it degrades or breaks.
Behavioral driven testing
This is influenced by BDD – Behavior driven development which is at the core TDD – Test driven development where development of software is defined by very specific test cases. In the case of BDD, the tests are defined in terms of a user story. This affects how you would write unit tests and acceptance tests. Testing frameworks like cucumber support this kind of writing of user stories.
Every bit of function you write should (must) be unit tested. It should be the most basic test that is used with any code that goes into production.
Basic principles of unit testing.
Test the smallest testable part of an application. That is a unittest.
Write your function to handle a particular error – i.e. division by zero.
test fixture – what’s needed to perform a test
Write a test case – 1/0
Write an assertion. Unit test assertion functions are very simple, they are functions that call your function and compares the returned result or state or value. For instance if you function returns a numeric value, you may use an assertion like
functionx > 0
This is dependent on your framework or library as far as if it supports different conditions for testing assertion.
You can read more about unit testing here.
This is also very important. What if the guys who are responsible for writing the database interface makes a change that the busness logic guy didn’t know about or the frontend guys didn’t know about the change in the functions for business logic. Your code justs breaks and that’s not good for your mental health. You can read more about integration testing here.
This is what your customer sees and interacts with. This is probably the most time consuming part of writing tests for. Never the less, if the customer is not able to press the “pay” button, you and your company are going to lose money…and that’s not good. Your going to catch this with a good automated testing approach. These days if your testing a web app or website, use selenium or a framework that drive selenium to test the web interface with clicks and data input values. You can record your test using the Selenium IDE in Firefox or Chrome. It will take some massaging of your recording to make a good automated acceptance test.
Depending on your testing strategy, your approach and framework you will use will vary. Regardless of your approach, I’ll always recommend unit testing your code.
Tying it in to DevOps
Continuous integration is a strategy and software testing being both a strategy for instance Behavior driven development with various frameworks as tactics such as cucumber as a framework that supports Behavior driven testing.
Without software testing and a sound testing methodology, you couldn’t have Continuous integration. That is the Holy Grail of DevOps.
I am open to any comments or suggestions to this article. Until then have a good day.