Chapter 10: Testing Strategies
Testing Strategies
Section titled “Testing Strategies”Go has excellent built-in testing support. Let’s explore patterns that make your tests maintainable and effective.
Testing is built into Go from the ground up. No external frameworks required - the testing package in the standard library provides everything you need. This simplicity encourages testing and makes it a natural part of Go development.
Go’s testing philosophy emphasizes clarity over cleverness. Tests are just Go code. No magic assertions, no complex DSLs, just functions that call code and report failures. This directness makes tests easy to read, write, and debug.
This chapter covers table-driven tests (the Go idiom for multiple test cases), subtests for organization, mocking strategies, HTTP testing, and test coverage. You’ll learn patterns that scale from simple functions to complex systems.
Basic Test Structure
Section titled “Basic Test Structure”How Go Tests Work
Section titled “How Go Tests Work”Tests live in _test.go files alongside the code they test. Test functions start with Test and accept *testing.T. Call methods on t to report failures. Run tests with go test. That’s it - no configuration, no test runners, no plugins.
Table-Driven Tests
Section titled “Table-Driven Tests”The Go Testing Idiom
Section titled “The Go Testing Idiom”Table-driven tests are Go’s standard pattern for testing multiple cases. Instead of writing separate test functions for each case, you define a slice of test cases and loop over them. This reduces duplication, makes adding new cases trivial, and keeps tests maintainable.
Why table-driven tests:
- Less duplication: Write test logic once, apply to many cases
- Easy to extend: Adding new test cases is just adding to the slice
- Clear intent: Test data is separate from test logic
- Better failures: See exactly which case failed and why
The pattern: define a struct with inputs, expected outputs, and a name field. Loop over test cases, run each one, report failures with context.
Example:
Subtests
Section titled “Subtests”Use t.Run() for better organization and selective test running:
Testing with Interfaces (Mocking)
Section titled “Testing with Interfaces (Mocking)”Testing HTTP Handlers
Section titled “Testing HTTP Handlers”Test Helpers
Section titled “Test Helpers”Key Takeaways
Section titled “Key Takeaways”- Table-driven tests - the Go way for multiple test cases
- Subtests with t.Run() - organize and run selectively
- Interface-based mocking - inject dependencies for testing
- httptest package - test HTTP handlers without a server
- Test helpers - reduce duplication, mark with
t.Helper() - Naming convention -
TestXxx(t *testing.T)for tests
Exercise
Section titled “Exercise”Test a REST API Handler
Write table-driven tests for a user creation handler that validates input and returns appropriate status codes.
Next up: Chapter 11: Benchmarking & Profiling