Chapter 5: Dependency injection

This chapter explores how to decouple code from its dependencies to improve testability and maintainability.

Topics covered

• Exploring challenges to testability
• Improving testability by isolating dependencies
• Using dependency injection techniques for testability

Sections

Section 1: Challenges to testability

• This section has no listings.

Section 2: Testable programs

• Listing 5.1: The env type

Section 3: Decoupling

• Listing 5.2: Refactoring the main function
• Listing 5.3: Setting FlagSet's output
• Listing 5.4: Preparing for the HIT client

Section 4: CLI tests

• Listing 5.5: Test environment
• Listing 5.6: Test runner helper
• Listing 5.7: Adding CLI tests

Section 5: Unit testing

• Listing 5.8: Adding a shared test case type
• Listing 5.9: Testing with valid flags