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We've been attempting to learn how to use TDD when developing apps lately. Nonetheless, We still only write exams sometimes.
However, We will do our best to record and apply the lessons We have learned on this blog. We will define test-driven development in general and demonstrate its application to iOS using Swift and an essential login feature.
Most iOS developers currently severely disregard the crucial duty of writing tests, and this behavior should contribute to the development of a new culture in which writing tests is part of the code creation process. It's great to have support when you make mistakes, so please let us know if there is anything We need to look into.
Test Driven Development (TDD): What is it?
Simply put, Test Driven Development (TDD) is a software development methodology that emphasizes writing unit test cases before writing code.
It is an iterative process that blends refactoring, unit test generation, and programming.
- Extreme Programming and the Agile Manifesto are the roots of the TDD methodology.
- The test process drives software development, as the name implies.
- It's also a structural technique that gives developers and testers optimal code that turns out to be long-lasting.
Using TDD, developers build brief test cases for each feature based on their preliminary knowledge. This technique's main goal is to write new or modified code solely in the event that the tests are unsuccessful, avoiding test script duplication.
Examples Of Test-Driven Development (TDD)
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Calculator Function: The first steps in creating a calculator function are using a TDD methodology, creating a test case for the "add" function, and then implementing the necessary code to pass the test.
More test cases for other tasks like "subtract," "multiply," and "divide" would be prepared after the "add" function is operating well.
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User Authentication: The first steps in creating a user authentication system are using a test-driven development technique for iOS apps, creating a test case for the user login capability, and writing the login process's code to pass it.
After the login functionality functions properly, more test cases for registration, password resets, and account verification will be prepared.
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E-commerce Website: Using a test-driven development (TDD) strategy, an e-commerce website would create test cases for every feature, including product listings, shopping cart functionality, and the checkout procedure.
Tests would be designed to ensure the system functions properly at every step, from adding products to the basket to finishing the transaction.
Traditional Testing Vs. TDD
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Methodology: Test-driven development (TDD) is an agile development approach in which tests are written before code is written.
Conventional testing, on the other hand, happens after the code is written.
- Testing Scope: While traditional testing encompasses testing the system as a whole, including functional, acceptability, and integration testing, TDD concentrates on testing small code units simultaneously.
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Iterative: TDD works iteratively, developing, testing, and fine-tuning small code sections until they pass every test.
Typically, the code is evaluated once and refined in response to the findings in traditional testing.
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Debugging: To facilitate debugging and error correction, TDD strives to identify faults as early in the development process as possible.
Debugging issues found later in the development phase may necessitate extra work in traditional testing.
- Documentation: Traditional testing documentation may provide more in-depth details on the testing procedure, the test environment, and the tested system, whereas TDD documentation usually concentrates on the test cases and their outcomes.
TDD for iOS Apps provides a more dependable and effective method for developing software by guaranteeing that code is extensively tested before system integration.
However, traditional testing might be more suited for larger and more complex projects where a more thorough approach to testing is needed.
Three Stages Of Development Based On Testing
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Write Exact Tests: To confirm the operation of particular features, developers must write accurate unit tests.
To enable the test to run, they must ensure it compiles.
The test is almost always going to fail.
Given that developers build concise tests based on their presumptions about the behavior of the feature, this is a significant failing.
- Fixing The Code: When a test fails, developers must make the minimum adjustments to the code so that it re-executes properly.
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Refactor The Code: After the test has been completed successfully, look for redundancy or potential code improvements to improve overall performance.
Make sure that refactoring does not impact the program's external behavior.
Read More: 5x Efficiency: Embracing Agile Methodologies for iOS App Development
How To Perform TDD
Test Driven Development for iOS is an iterative process that prioritizes testing over coding.
As new features are added, the test cases will continue to expand in size.
Step 1: Composing An Exam
So, let's open XCode and create a new project. It has our name, Weatherly. If you forgot to include the test targets when creating the project, you can easily add them using File -> New -> Target -> Unit Testing Bundle.
We will be provided with a test file that subclasses XCTestCase and creates a new target named WeatherryTests. This is where the entire test starts. We are considering testing this blog's login option. What am We going to test first? In any case, email and password validation will be part of the login feature.
There will be a LoginViewModel underneath the validation.
Step 2: Execute The Exam
Okay, so... It cannot be run; merely et. There are two potential explanations for the build's failure. Check your imports first.
Ensure you use @testable import YourApp to import your project module into the test module. Remember to import your primary module. The second explanation is that your application does not contain the LoginViewModel.
That's the rationale in this instance. Let's proceed to the following action.
Step 3: Let’s Write Some Code
Now let's build the LoginViewModel. That said, the LoginViewModel is still a stupid class with no idea what to do.
As you code, you'll see that each error disappears individually. One more mistake. The login method is now the source of the issues. We are following our test, as you can see. How awesome is that? Since we still lack a login mechanism, let's create one now.
Login and validation using LoginViewModel. Swift You can view the validator here in our gist if you'd like.. The mistakes have vanished now. Alright, let's…
Step 4: Execute The Evaluation And Rework
Test With The Build Button
You have two options for running the test: use the Build button on the upper left corner or press CMD + U. Tap the button to bring up the Test menu.
You can see a joyful green over there now. Yes, that is the case, as We built the Form Validator beforehand. And I'm going through a test and code cycle in tandem with the building process.
To make the test run, keep pressing Ctrl + U. We STRONGLY SUGGEST CODING FIRST ON YOUR OWN
Why? Because you will inevitably make mistakes when coding, and your tests will catch those errors. It will display the red symbol.
This is where TDD's art truly shines. You proceed case by case; some may be successful, some may not be. It prevents you from making the same errors or breaking additional code.
We saw a clever coder on YouTube who stated: You advance even if a test is unsuccessful.
Writing a failing test is, therefore, a crucial task. Refactoring is the cleanup of code. Here's where you can attempt to assess your code using SOLID principles.
Perhaps you're having trouble with SRP in your code or wondering why our constructor has so many parameters. Does this app have enough modules? Does adding a new feature require us to change this code in any way?
Anticipate the future, but don't overthink it—apps are dynamic. Here, you can quickly implement design patterns by composing your dependencies, adding adapters, creating Factories, and adding Strategy Patterns.
Your code structures might be altered frequently. Also, you'll feel confident completing it. WHY? Since you have trustworthy tests in place to ensure that you don't break any functionalities.
Step 5: Repeat
Create a test that fails, add some code, rerun it, make changes, and repeat.
Conclusion
At first, test-driven development is challenging. We still find it challenging to complete this work. However, if you attempt to do it often and apply it to every project you work on, it will eventually become second nature.
Making tests makes you more valuable. Maintaining your program's "soft" and "safe" nature is essential for iOS developers. That is the difference between an expert and an average developer.
The Weathery repository will remain on GitHub. However, as We learn best TDD for iOS, SOLID, and design patterns, it may alter over time.
We would be very grateful if you would assist us in becoming an expert iOS developer. We advise you to listen to this playlist if you feel there is a lack of explanation or examples. We were really inspired by it.
