What about the last time your organization decided to implement a CRM suite? You likely tested it before you decided to purchase, right? And what if, in your evaluation, the car or software didn't work?
With custom software, there's no alternative. You're writing it and delivering it to your customer. Does your code work? Unit testing is one means to exercise your code to make sure the code operates in conformity with its specification. If you can never get to delivery because your unit tests are difficult to write, the problem, in that case, isn't with the tests.
This is where unit testing opponents think they have their best argument because they'll see this scenario as proof that unit testing is bad because it delays software delivery. I don't think I have to spell out just how logically flawed the unit testing naysayer arguments are. The earlier you can implement your software, the quicker you can achieve failure. And in achieving failure, you can remediate the issues and achieve superior software in the process.
The question is how do you know if your software fails? Unit testing is one good way. People want documentation on how software works. Nobody really likes writing documentation. Unit tests are a form of documentation because they express how software is supposed to work for a given context.
I'm not suggesting that unit-tests are what you send your end-user to. But for new developers on the team, there's no better way to grok the software, specifically, how the software is built as to form, patterns, and practices. Organizations often complain about the costs incident to bringing a new developer online. Unit tests are a great way to help reduce those costs. Software requirements change over time. We've all been in the position of needing to implement changes to existing features.
We've also been tasked with providing an estimate on how much effort is required to implement a change. In the absence of unit tests, we guess. Such guesses are based on intuition and experience, which isn't to say that they have no value if unit-tests aren't present. In such cases, only your most experienced developers could be relied upon. What if, on the other hand, you had good unit test coverage? You could spike up the change and run the tests. If there were massive test failures as a result of the change, you have some decisions to make.
The first is whether or not you implemented the change correctly. Second, assuming you implemented the change in the only way you could, you now have to confront the cost benefits of the requested feature modification. Part of that effort might require a refactoring effort to make your code more amenable to the requested change. Without unit-tests, the SWAG taken to determine the effort likely wouldn't account for this additional effort. The key take-away is that unit-tests provide an opportunity to get an objective measure of at least part of the cost of a new feature.
Let's assume that you have a feature that handles credit card authorizations. The feature calls out to an external service and in response, the requested charge is approved or denied. A third option is no response at all i.
The application must react differently based on the response or lack of response. Let's further assume that the code is closed, in that it takes no parameters. Somewhere in the system, there's the credit card information as well as the purchase amount to make the approval request. Such code is incapable of being unit tested because the code does multiple things.
In other words, it doesn't conform to the Single Responsibility Principle. By injecting dependencies, you can mock contexts and behaviors so that you may simulate reality and thereby test to see how the software reacts. If you can't write a unit test because there's no way to inject dependencies, you're signing up for a very expensive proposition. Your software will end up costing more to develop and support. And when the time comes for new features, good luck with that implementation.
The additional costs you'll incur plus the opportunity costs associated with not being able to implement new features is what's called technical debt. How do you know a line of code will ever be executed? If you have valid unit tests, you can quickly determine whether or not code is actually run. In my practice, I use JetBrains tools like R and dotCover to run my unit tests and provide metrics on code coverage.
At a glance, in the development context, I can quickly determine whether code is ever hit. If it's not, I have questions to ask. One question is whether I have sufficient test coverage.
If I've accounted for all the scenarios, the code can be eliminated. If not, I have at least one more test to write. If the additional tests require a lot work to set up, that's an indication of high cyclomatic complexity. By now, it should be apparent that all of these factors relate to one another.
Taken together, you can safely assume that unit testing leads to better software. That, however, is a K-foot statement. Without sufficient details to back that claim up, it's merely conjecture and allows the unit testing naysayers to prevail. Myths by their very nature are false assumptions. These assumptions lead to a vicious cycle as follows —. Programmers think that Integration Testing will catch all errors and do not execute the unit test.
Once units are integrated, very simple errors which could have very easily found and fixed in unit tested take a very long time to be traced and fixed. Skip to content.
What is Unit Testing? Why Unit Testing? How to do Unit Testing In order to do Unit Testing , developers write a section of code to test a specific function in software application. These assumptions lead to a vicious cycle as follows — Truth is Unit testing increase the speed of development.
Techniques, Example Test Cases. Report a Bug. Previous Prev. Next Continue. Home Testing Expand child menu Expand. SAP Expand child menu Expand. Web Expand child menu Expand. Must Learn Expand child menu Expand. It's a time trade off. Other times, someone will come in after the fact and write tests to help create safe guards while they refactor or further develop that area of the code base. Hammers are great tools and can help you with lots of different jobs -- opening car windows or turning off alarm clocks.
But, there are especially well suited to putting nails through hard surfaces. Unit tests are similar. They can do lots of different things, they should probably only do a few.
Test Driven Development, or TDD, is a code design technique where the programmer writes a test before any production code, and then writes the code that will make that test pass. The idea is that with a tiny bit of assurance from that initial test, the programmer can feel free to refactor and refactor some more to get the cleanest code they know how to write. The idea is simple, but like most simple things, the execution is hard. TDD requires a completely different mind set from what most people are used to and the tenacity to deal with a learning curve that may slow you down at first.
TDD isn't new, but at this point it is still mostly for the go getters. The rest of us are checking our work. Writing unit tests after you have written the production code may be a more traditional way of doing it, but it is no less useful. It's also something you're familiar with if you have been in a math class any time in the past ten years. After your work is checked and it is clear that the code is doing what you think it is doing, the value of the unit tests change a little bit.
Tests that can be easily run with every build of your product act as change detection notifying you when code changes in unexpected ways. Code documentation is a drag, and it shows, mostly by how little code documentation gets written. Unit testing can make the documentation burden a little easier by encouraging better coding practices and also leaving behind pieces of code that describe what your product is doing.
Rather than having to constantly feed the documentation beast with code change, you'll be updating a system of checks that is working for you. There are a few uses of unit testing that you will want to avoid when possible. Creating integration tests that cross system borders and touch databases or 3rd party systems can be done, but this quickly results in a test suite that takes longer and longer to run with each added test.
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