On preventing your test suite from becoming too user interface-heavy

In August of last year, I published a blog post talking about why I don’t like to think of automation in terms of frameworks, but rather in terms of solutions. I’ve softened a little since then (this is probably a sign of me getting old..), but my belief that building a framework might lead to automation engineers subsequently trying to fit every test left, right and center into that framework still stands. One example of this phenomenon in particular I still see too often: engineers building a feature-rich end-to-end automation framework (for example using Selenium) and then automating all of their tests using that framework.

This is what I meant in the older post by ‘framework think’: because the framework has made it so easy for them to add new tests, they skip the step where they decide what would be the most efficient approach for a specific test and blindly add it to the test suite run by that very framework. This might not lead to harmful side effects in the short term, but as the test suite grows, chances are high that it becomes unwieldy, that the time it takes to complete a full test run becomes unnecessarily long and that maintenance efforts are not being outweighed by the added value of having the automated tests any more.

In this post, I’d like to take the practical approach once more and demonstrate how you can take a closer look at your application and decide if there might be a more efficient way to implement certain checks. We’re going to do this by opening up the user interface and see what happens ‘under the hood’. I’m writing this post as an addendum to my ‘Building great end-to-end tests with Selenium and Cucumber / SpecFlow‘ course, by the way. Yes, that’s right, one of the first things I talk about during my course on writing tests with Selenium is when not to do so. I firmly believe that’s the on of the very first steps towards creating a solid test suite: deciding what should not be in it.

The application under test
The application we’re going to write tests for is an online mortgage orientation tool, provided by a major Dutch online bank. I’ve removed all references to the client name, just to be sure, but it’s not like we’re dealing with sensitive data here. The orientation tool is a sequence of three forms, in which people that are interested in a mortgage fill in details about their financial situation, after which the orientation tool gives an indication of whether or not the applicant is eligible for a mortgage, as well as an estimate of the maximum amount of the mortgage, the interest rate and the monthly installments payable.

Our application under test - the mortgage orientation tool

What are we going to automate?
Now that we know what our application under test does, let’s see what we should automate. We’ll assume that there is a justified need for automated checks in the first place (otherwise this would have been a very short blog post!). We’ll also assume that, maybe for tests on some other part of the bank’s website, there is already a solid automation framework written around Selenium in place. So, this being a website and all, it makes sense to write some additional checks and incorporate them into the existing framework.

First of all, let’s try and make sure that the orientation tool can be used and completed, and that it displays a result. I’d say, that would be a good candidate for an automated test written using Selenium, since it confirms that the application is working from an end user perspective (there is value in the test) and I can’t think of a lower level test that would give me the same feedback. Since there are a couple of different paths through the orientation tool (you can apply for a mortgage alone or with someone else, some people have a house to sell while others have not, there are different types of contracts, etc.), I’d even go as far as to say you’ll need more than one Selenium-based test to be able to properly claim that all paths can be traversed by an end user.

Next, I can imagine that you’d want to make sure that the numbers that are displayed are correct, so your customers aren’t misinformed when they complete the orientation tool. This would lead to some massive issues of distrust later on in the mortgage application process, I’d assume.. Since we’ve been able to add the previous tests so easily to our existing framework, it makes sense to add some more tests that walk through the forms, add the data required to trigger a specific expected outcome and verify that the result screen we saw in the screenshot above displays the expected numbers. Right?

No. Not right.

It’s highly likely that the business logic used to perform the calculation and serve the numbers displayed on screen isn’t actually implemented in the user interface. Rather, it’s probably served up by a backend service containing the business logic and rules required to perform the calculations (and with mortgages, there are quite a few of those business rules, I’ve been told..). The user interface takes the values entered by the end user, sends them to a backend service that performs calculations and returns the values indicating mortgage eligibility, interest rate, height of monthly installment, etc., which are then interpreted and displayed again by that same user interface.

So, since the business logic that we’re verifying isn’t implemented in the user interface, why use the UI to verify it in the first place? That would highly likely only lead to unnecessarily slow tests and shallow feedback. Instead, let’s look if there’s a different hook we can use to write tests.

I tend to use on of two different tactics to find out if there are better ways to write automated tests in cases like these:

  1. Talk to a developer. They’re building the stuff, so they’ll probably know more about the architecture of your application and will likely be happy to help you out.
  2. Use a network analyzing tool such as Fiddler or WireShark. Tools like these two let you see what happens ‘under water’ when you’re using the user interface of a web application.

Normally, I’ll use a combination of both: find out more about the architecture of an application by talking to developers, then using a network analyzer (I prefer Fiddler myself) to see what API calls are triggered when I perform a certain action.

Analyzing API calls using Fiddler
So, let’s put my assumption that there’s a better way to automate the tests that will verify the calculations performed by the mortgage orientation tool to the test. To do so, I’ll fire up Fiddler and have it monitor the traffic that’s being sent back and forth between my browser and the application server while I interact with the orientation tool. Here’s what that looks like:

Traffic exchanged between client and server in our mortgage orientation tool

As you can see, there’s a mortgage orientation API with a Calculate operation that returns exactly those numbers that appear on the screen. See the number I marked in yellow? It’s right there in the application screenshot I showed previously. This shows that pretty much all that the front end does is performing calls to a backend API and presenting the data returned by it in a manner attractive to the end user. This means that it would not make sense to use the UI to verify the calculations. Instead, I’d advise you to mimic the API call (or sequence of calls) instead, as this will give you both faster and more accurate feedback.

To take things even further, I’d recommend you to dive into the application even deeper and see if the calculations can be covered with a decent set of unit tests. The easiest way to do this is to start talking to a developer and see if this is a possibility, and if they haven’t already done so. No need to maintain two different sets of automated checks that cover the same logic, and no need to cover logic that can be tested through unit tests with API-level checks..

Often, though, I find that writing tests like this at the API level hits the sweet spot between coverage, effort it takes to write the tests and speed of execution (and as a result, length of the feedback loop). This might be because I’m not too well versed in writing unit tests myself, but it has worked pretty well for me so far.

Deciding what to automate where: a heuristic
The above has just been one example where it would be better (as well as easier) to move specific checks from the UI level to the API level. But can we make some more generic statements about when to use UI-level checks and when to dive deeper?

Yes, we can. And it turns out, someone already did! In a recent blog post called ‘UI Test Heuristic: Don’t Repeat Your Paths‘, Chris McMahon talked about this exact subject, and the heuristic he presents in his blog post applies here perfectly:

  • Check that the end user can complete the mortgage orientation tools and is shown an indication of mortgage eligibility and associated figures > different paths through the user interface > user interface-level tests
  • Check that the figures served up by the mortgage orientation tool are correct > repeating the same paths multiple times, but with different sets of input data and expected output values > time to dive deeper

So, if you want to prevent your automated test suite from becoming too bloated with UI tests, this is a rule of thumb you can (and frankly, should) apply. As always, I’d love to hear what you think.

Why there’s no such thing as codeless automation

In today’s blog post – which, again, is really nothing more than a thinly veiled rant – I’d like to cover something that’s been covered before, just not by me: codeless test automation and why I think there isn’t and should not be such a thing.

I’ve seen numerous ‘solution’ vendors advertise their products as ‘codeless’, implying that everybody in the team will be able to create, run and maintain automated tests, without having to, well, write code. I’ve got a number of problems with selling test automation in this way.

It’s not codeless. It’s hiding code.
The first gripe I have with ‘codeless’ automation is a semantic one. These solutions aren’t codeless at all. They simply hide the code that runs the test from plain sight. There are no monkeys in the solution that magically execute the instructions that make up a test. No, those instructions are translated into actual code by the solution, then executed. As a user of such a solution, you’re still coding (i.e., writing instructions in a manner that can be interpreted by a machine), just in a different syntax. That’s not codeless.

While it might be empowering, it’s also limiting.
Sure, using codeless tools might potentially lead to more people contributing to writing automated tests (although from my experience, that’s hardly how it’s going to be in the end). The downside is: it’s also limiting the power of the automated tests. As I said above, the ‘codeless’ solution is usually nothing more than an abstraction layer on top of the test automation code. And with abstraction comes loss of detail. In this case, this might be loss of access to features of the underlying code. For example, if you’re using a codeless abstraction on top of Selenium, you might lose access to specific waiting, synchronization or error handling mechanisms (which are among the exact things that makes Selenium so powerful).

It might also be loss of access to logging, debugging or other types of root cause analysis tools, which in turn leads to shallower feedback in case something goes wrong. While the solution might show you that something has gone wrong, it loses detail on where things went wrong and what caused the failure. Not something I like.

Finally, it might also limit access to hooks in the application, or limit you to a specific type of automated tests. If such a solution makes it potentially easier to write automated tests on the user interface level, for example, there’s significant risk that all tests will be written at that level, even though that might not be the most efficient approach in the first place. If all you’ve got is a hammer…

It’s doing nothing for the hard problems in creating maintainable automation.
Let’s face it: while writing code might seem hard to people that haven’t done it before, it actually isn’t that difficult once you’ve had a couple of basic programming classes, or followed a course or two on Codecademy. What is hard is writing good, readable, maintainable code. Applying SOLID and DRY principles. Structuring your tests. Testing the right thing at the right level. Creating a solid test data and test environment strategy. Those things are hard. And codeless test automation does nothing for those problems. As I tried to make clear in the previous paragraphs, it’ll often make it even harder to solve those problems effectively.

I’m all for creating solutions that make it easier to write, run and maintain automation. I hate people selling solutions as something they’re not. Codeless test automation is not going to solve your test automation problems. People that know

  • how to decide what good automation is
  • how to write that automation, and
  • how to pick the tools that will help them achieve the goals of the team and organization


Why I think unit testing is the basis of any solid automation strategy

In a recent blog post I talked about why and how I still use the test automation pyramid as a model to talk about different levels of test automation and how to combine them into an automation strategy that fits your needs. In this blog post I’d like to talk about the basis of the pyramid a little more: unit tests and unit testing. There’s a reason -or better, there are a number of reasons- why unit testing forms the basis of any solid automation strategy, and why it’s depicted as the broadest layer in the pyramid.

Unit tests are fast
Even though end-to-end testing using tools like Selenium is the first thing a lot of people think about when they hear the term ‘test automation’, Selenium tests are actually the hardest and most time-intensive to write, run and maintain. Unit tests, on the other hand, can be written fast, both in absolute time it takes to write unit test code as well as relative to the progress of the software development process. A very good example of the latter is the practice of Test Driven Development (TDD), where tests are written before the actual production code is created.

Unit tests are also fast to run. Their run time is typically in the milliseconds range, where integration and end-to-end tests take seconds or even minutes, depending on your test and their scope. This means that a solid set of unit tests will give you feedback on specific aspects of your application quality much faster than those other types of tests. I stressed ‘specific aspects’, because while unit tests can cover ground in relatively little time, there’s only so much they can do. As goes for automation as a whole.

Unit tests require (and enforce) code testability
Any developer can tell you that the better structured code is, the easier it is to isolate specific classes and methods and write unit tests for them, mocking away all dependencies that method or class requires. This is referred to as highly testable code. I’ve worked in projects where people were stuck with badly testable code and have seen the consequences. I’ve facilitated two day test automation hackathon where the end goal was to write a single unit test and integrate it into the Continuous Integration pipeline. Writing the test took ten minutes. Untangling the existing code so that the unit test could be written? Two days MINUS ten minutes.

This is where practices like TDD can help. When you’ve got your tests in place before the production code that lets the tests pass is written, the risk of that production code becoming untestable spaghetti code is far lower. And having testable code is a massive help with the next reason why unit testing should be the basis of your automation efforts.

Unit tests prevent outside in test automation (hopefully)
If you’re code is testable, it means that it’s far easier to write unit tests for it. Which in turn means that the likelihood that unit tests are actually written increases as well. And where unit tests are written consistently and visibly, the risk that everything and its mother it tested through the user interface (a phenomenon I’ve seen referred to as ‘outside-in test automation’) is far less high. Just writing lots of unit tests is not enough, though, their scope, intent and coverage should be clear to the team as well (so, testers, get involved!).

Unit tests are a safety net for code refactoring
Let’s face it: your production code isn’t going to live unchanged forever (although I’ve heard about lines of COBOL that are busy defying this). Changes to the application, renewed libraries or insights, all of these will in time be reason to refactor your existing code to improve effectivity, readability, maintainability or just to keep things running. This is where a decent set of unit tests helps a lot, since they can be used as a safety net that can give you feedback about the consequences of your refactoring efforts on overall application functionality. And even more importantly, they do this quickly. Developers are humans, and will move on to different tasks if they need to wait hours for feedback. With unit tests, that feedback arrives in seconds, keeping them and you both focused and on the right track.

In the end, unit tests can, will and need not replace integration and end-to-end tests, of course. There’s a reason all of them are featured in the test automation pyramid. But when you’re trying to create or improve your test automation strategy, I’d advise you to start with the basis and get your unit testing in place.

By the way, for those of you reading this on the publication date, I’d like to mention that I’ll be co-hosting a webinar with the folks at Testim, where I’ll be talking about the importance of unit testing, as well as much more with regards to test automation strategy. I hope to see you there! If you’re reading this at a later date, I’ll add a link to the recording as soon as it’s available.