Unit Testing in Go — Patterns from real projects¶

Full documentation site: https://padiazg.github.io/unit-test-book

A hands-on guide to Go unit testing through real-world patterns extracted from 7 production Go projects.

Each chapter is a standalone Go module with production code, tests, and an explanation of the testing approach.

Table of Contents¶

#	Chapter	Pattern	Source
01	Classic Table-Driven Tests	`wantErr bool`	pantry/domain, hexago/version
02	Value Assertions	`want T` + deep equal	go-testgen/utils, hexago/version
03	Fields Struct for Inputs	Grouped input structs	hexago/version
04	Subtest Naming Strategies	Constants as test names	hexago/version

#	Chapter	Pattern	Source
05	Typed Check Functions	`type checkXxxFn func(...)`	pantry, jokes
06	Check Collection Builder	`var checkXxx = func(fns...)`	notifier, pantry
07	Check Factory Closures	`checkStatus(want)` closures	go-crap, pantry
08	Error Message Verification	`assert.Contains(err.Error())`	notifier, pantry
09	Output String Inspection	`assert.Contains/NotContains`	go-testgen

#	Chapter	Pattern	Source
10	The `before` Hook Pattern	`before func(*SUT)`	notifier, pantry, jokes
11	HTTP Client Interface Mock	`HTTPClient` + `mockHTTPClient`	notifier, ollama-tools
12	RoundTripper Mock	`DryRunTransport`	ollama-tools
13	testify/mock for Interfaces	`mock.Mock` + `.On().Return()`	pantry, notifier/amqp
14	Function Variable Injection	`jsonMarshal`, `httpNewRequest`	notifier
15	Package-Level Var Swap	`randRead` override + defer restore	notifier/utils

#	Chapter	Pattern	Source
16	httptest.Server Integration	Real HTTP test server	notes
17	httptest.ResponseRecorder	Handler unit tests	pantry/http
18	Error Readers	`errorReader` for IO errors	notes
19	Temporary Files & Parsing	`t.TempDir()` + file ops	go-testgen, go-crap

#	Chapter	Pattern	Source
20	Channel Delivery Tests	Buffered channel + select	notifier
21	Panic Recovery in Tests	`defer recover()` + `wantPanic`	notifier
22	Goroutine Run Loops	`go n.Run()` + WaitGroup	notifier

#	Chapter	Pattern	Source
23	Goroutine Leak Detection	`goleak.VerifyTestMain`	go-crap
24	AST Parsing for Cyclomatic Complexity	`go/parser` + `go/ast`	go-crap/complexity
25	Benchmark Tests	`b.Benchmark` + `b.Loop()`	go-testgen, go-crap
26	Parallel Tests	`t.Parallel()`	pantry/database

#	Chapter	Pattern	Source
27	Service Layer with Mocked Ports	`setupService` + `Teardown`	pantry/services
28	JSON Format Verification	Marshal/unmarshal roundtrip	go-crap/report
29	Setup/Teardown Fixtures	Fixture struct + teardown	pantry/services

# Run tests for a specific chapter
cd chapter-01-classic-table-driven
go test -v ./...

# Run all tests
go test ./chapter-*/...

Path	Description
`chapter-XX-*/`	29 standalone Go modules with code + tests + README
`doc/`	MkDocs site (generates the documentation site)
`doc/docs/`	Generated markdown pages (37 files)
`doc/generate.py`	Script that builds mkdocs pages from chapter READMEs
`doc/mkdocs.yml`	MkDocs site configuration

cd doc
pip install mkdocs-material pymdown-extensions
mkdocs serve

The patterns in this book are extracted from these production Go projects:

Project	Description
hexago	Go project scaffolding with hexagonal architecture
jokes	Joke API client
go-testgen	Go test generator
go-crap	CRAP score analysis tool
ollama-tools	Ollama model tools
pantry	Inventory management with hexagonal architecture
notifier	Multi-channel notification system