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Android testing

Why do we write tests?​

Testing is an essential part of software development. While there are different kinds of tests, each serving a unique purpose, they all exist for the same fundamental reason: humans make mistakes. Tests are designed to catch these mistakes as early as possible in the development process.

By identifying issues before they reach production, we save our users from frustration and ourselves from spending time debugging. Writing tests may feel like extra effort at first, but the value becomes clear when a test catches an issue before it impacts the end user.

Benefits of writing tests​

  • Early issue detection: Catch bugs before they reach production.
  • Improved code quality: Tests encourage better design and maintainability.
  • Time savings: Debugging production issues is far more time-consuming than resolving issues during development.
  • User satisfaction: Fewer bugs in production lead to a better user experience.

How to write effective tests​

To ensure clarity and maintainability, test functions should always (when possible) be written as descriptive sentences. Ideally, they should follow the GIVEN-WHEN-THEN structure. This approach makes tests easier to understand at a glance, even for complex scenarios.

Example of a well-named test:

@Test
fun `Given a user with Home Assistant when they open the app then they see the default dashboard`() {
    // Test implementation here
}

Why use GIVEN-WHEN-THEN?​

  • GIVEN: Describes the initial context or setup.
  • WHEN: Specifies the action or event being tested.
  • THEN: Defines the expected outcome or result.

This structure ensures that tests are both readable and self-explanatory, making it easier for developers to understand the purpose of the test without diving into the implementation.

Types of tests​

While this document focuses on Android testing, it’s important to understand the different types of tests and their purposes:

  1. Unit tests: Validate individual components or functions in isolation.
  2. Integration tests: Ensure that different parts of the application work together as expected.
  3. UI tests: Verify the user interface and user interactions.
  4. End-to-End tests: Test the entire application flow from start to finish.

Each type of test has its place in the development process, and a well-tested application often includes a combination of all these types.

Best practices for writing tests​

  • Keep tests small and focused: Each test should validate a single behavior or scenario.
  • Use descriptive names: Test names should clearly describe what is being tested and the expected outcome.
  • Avoid dependencies: Tests should be independent of each other to ensure reliability.
  • Mock external dependencies: Use mocks or fakes to isolate the code under test.

By following these guidelines, you can write tests that are both effective and maintainable.