How to do TDD in swiftUI apps

To implement Test-Driven Development (TDD) in SwiftUI apps, you can leverage the new Swift testing features introduced at WWDC 2024. Here are the steps and key concepts to get you started:

1. Set Up Your Test Target:

   • Add a test bundle target to your project. In Xcode, choose File > New > Target, then search for Unit Testing Bundle in the test section. Swift testing is the default choice for this template in Xcode 16.
   • Meet Swift Testing

2. Write Your First Test:

   • Import the testing module and write a global function with the @Test attribute. This attribute indicates that a function is a test.
   • Example:

     import Testing
     
     @Test
     func testExample() {
         // Your test code here
     }
     

   • Meet Swift Testing

3. Use Expectations and Traits:

   • Swift testing uses #expect and #require macros for assertions. These macros allow you to write simple or complex Swift expressions to verify test results.
   • Example:

     @Test
     func testPlantingRoses() {
         let rose = Plant(type: .rose)
         #expect(rose.plantingStyle == .grafting)
     }
     

   • Meet Swift Testing

4. Organize and Filter Tests:

   • Use tags to group tests across different suites. Tags help in organizing and running specific groups of tests.
   • Example:

     extension Tag {
         static let planting = Tag("planting")
     }
     
     @Test(tags: [.planting])
     func testPlantingRoses() {
         // Test code
     }
     

   • What’s new in Xcode 16

5. Parallelization and Concurrency:

   • Swift testing supports parallel execution of tests using Swift concurrency. Each test runs in its own process, which helps in isolating state and improving test performance.
   • Meet Swift Testing

6. Common Workflows:

   • Customize tests or repeat them with different arguments. Use traits to specify conditions under which tests should run.
   • Example:

     @Test
     func testWithDifferentArguments() {
         for input in [1, 2, 3] {
             #expect(input > 0)
         }
     }
     

   • Meet Swift Testing

By following these steps and utilizing the new features in Swift testing, you can effectively implement TDD in your SwiftUI apps. For more detailed information, you can refer to the sessions mentioned above.