gs-mock

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The project has been officially released, welcome to use!

gs-mock is a modern, type-safe Go mock library with full support for generics. It solves the shortcomings of traditional Go mocking tools in type safety and complexity, and naturally supports concurrent testing through context.Context. Whether it’s interfaces, regular functions, or struct methods, everything can be mocked easily—making it ideal for unit tests in microservice projects.

Features

• Type-Safe & Generic Support
  Supports generic functions and interfaces, with IDE auto-completion for improved development experience
• Multiple Mocking Modes
  • Handle mode: handle all mock logic in a single callback
  • When/Return mode: execute different return logic based on conditions
• Multiple Parameters & Return Values
  Supports up to 5 parameters and 4 return values, enough for most function signatures
• Interface & Struct Method Mocking
  • Interfaces: mock code is generated automatically
  • Regular functions & struct methods: mocked via context.Context, avoiding the need for interface abstraction
• Concurrency Test Support
  Mock behavior is bound to the context chain, ensuring safe concurrent mocking
• Simplified API
  API is similar to gomock but cleaner and easier to use

Installation

Install directly:

go install github.com/go-spring/gs-mock@latest

Install via the gs toolkit:

/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/go-spring/gs/HEAD/install.sh)"

Quick Start

Interface Mocking

1. Define an interface

type Service interface {
    Do(n int) int
}

2. Generate mock code

//go:generate gs mock -o src_mock.go

Add the above directive at the top of the interface file to generate mock code for all interfaces in the package.
If you only need to generate mocks for specific interfaces, use -i. Prefixing an interface name with ! means exclusion.

//go:generate gs mock -o src_mock.go -i '!RepositoryV2,Repository'

3. Use the generated mock

r := gsmock.NewManager()
s := NewServiceMockImpl(r)

// Handle mode
s.MockDo().Handle(func (impl *ServiceMockImpl, n int) int {
    if n%2 == 0 {
        return n * 2
    }
    return n + 1
})

fmt.Println(s.Do(1)) // 2
fmt.Println(s.Do(2)) // 4

r.Reset()

// When/Return mode
s.MockDo().When(func (impl *ServiceMockImpl, n int) bool {
    return n%2 == 0
}).ReturnValue(2)

s.MockDo().When(func (impl *ServiceMockImpl, n int) bool {
    return n%2 == 1
}).ReturnValue(1)

fmt.Println(s.Do(1)) // 1
fmt.Println(s.Do(2)) // 2

Function Mocking

1. Define a regular function

//go:noinline // prevent inline optimization
func Do(ctx context.Context, n int) int { return n }

2. Mock the function

r := gsmock.NewManager()
ctx := r.WithManager(context.TODO())

gsmock.Mock21(Do, r).Handle(func (ctx context.Context, n int) int {
    return n * 2
})

fmt.Println(Do(ctx, 1)) // 2

Method Mocking

1. Define a struct

type Service struct{ m int }
func (s *Service) Do(ctx context.Context, n int) int { return n }

2. Mock the struct method

r := gsmock.NewManager()
ctx := r.WithManager(context.TODO())

gsmock.Mock31((*Service).Do, r).Handle(func (s *Service, ctx context.Context, n int) int {
    return n + s.m
})

fmt.Println((&Service{m: 1}).Do(ctx, 1)) // 2
fmt.Println((&Service{m: 2}).Do(ctx, 1)) // 3

⚠️ When running go test, add -gcflags="all=-N -l" to prevent method inlining.

License

This project is licensed under the Apache License Version 2.0.