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In the last section we discussed what TDD (Test Driven Development) is, how it is a test centered development process in which we start writing tests first. To begin with, these tests fail, but as we add more application code, these tests pass. BDD (Behavior Driven Development)is a software development methodology that has evolved from TDD (Test Driven Development). The primary factor that distinguishes them is the fact that it is written in a shared language, which enhances communication within the tech and non-tech teams and their stakeholders.
In both TDD & BDD development approaches, tests are written before writing the code, but in BDD, tests are more user-focused and based on the system’s behavior.
One major advantage of the BDD test cases being written in a common language is the particulars of how the application behaves can be easily comprehended by all. For instance, the test cases can be written with the help of real-time examples of the actual requirements, to explain the behavior of the system. In Agile environments, BDD plays a pivotal role as it enforces the use of Agile methodologies during the development as well as testing. Moreover, it facilitates effective knowledge sharing between end-users, BAs, QAs, and SEs of the software product.
BDD entails the following steps:
- Recognize a business feature.
- Categorize scenarios under the selected feature.
- Define steps for each scenario.
- Run the feature and fail.
- Write code to make steps pass.
- Refactor code and create reusable automation library.
- Run the feature and pass.
- Generate test results.
Features of BDD
- Imbibing a thought-shift from “tests” to “behavior”
- Group effort between Business stakeholders, Business Analysts, QA Team and developers
- Universal language that is easy to describe
- Driven by Business Value
- Outspreads Test Driven Development (TDD) by using natural language that non-technical stakeholders can also understand.
The ‘Given-When-Then’ formula:
One way to go about writing the BDD test cases for a user story is by applying the proposed template –
The Given scenario + When an action takes place + Then this should be the outcome.
Take for instance:
Given the User hasn’t entered any data on a download form
When they click the submit button
Then a proper authentication messages should be shown
Why the User matters more than you think?
At this point, ideally mapping your testing to real-world user behavior should make obvious sense. However, if it doesn’t, there is another BIG reason to use BDD - It could save you a lot of development time.
However, at times the developers can be borderline obsessive over the clean and beautiful code. Sometimes, it's also easy to slip into the habit of writing needless unit tests on code to test the factors that aren’t existent in the real world.
For instance, suppose that you are designing an app that allows the user to measure the dimensions of a room using a phone's built-in GPS. With the help of BDD, you could design tests for different scenarios, including the successful calculation of dimensions (e.g., "When I move in A direction 10 feet, And in B direction 10 feet, Then the app must tell me the area of the room is 100 square feet"). Apart from this, the BDD tests could also include corner cases, like what ought to happen when a user starts a measurement and then drops the phone or clicks the start button by mistake in between the measuring.
On the other hand, Unit tests can be written into the code to test how the software calculates different values and permutations, including negative values. But in a real-life situation, the movement of the user (and phone) can never generate a negative number.
BDD underlines the real-world scenarios with real users and nothing superfluous, ultimately making better use of testing resources.
In conclusion, a common misconception about TDD and BDD is that they are nothing but testing techniques, when in fact, they’re not. As the name suggests, TDD and BDD are all about software development. It is the process of approaching your design in such a way that you are forced to think about the desired outcome and API before you code.
If you need help with BDD, our experts would be glad to give you a hand. Get in touch with us today.