Hi Gophers 
,
I’d like to share a project I’ve been working on: gs-mock — a modern, type-safe mocking library for Go that fully supports generics.
Why another mocking library?
Traditional Go mocking tools often:
- Rely on reflection heavily, leading to runtime type errors.
- Require verbose setup code.
- Don’t fully leverage Go 1.18+ generics.
gs-mock solves these problems by providing compile-time safety and a much simpler API.
Key Features
-
Type-Safe: Built with Go generics, ensuring no runtime surprises.
-
Multiple Mocking Modes:
Handle: directly handle function calls.When/Return: conditionally return results.
-
Flexible Matching: Supports up to 5 parameters and 5 return values.
-
Context Integration: Works seamlessly with
context.Context. -
Auto Reset: Easily reset all mocks with
Manager.Reset(). -
Clear Errors: Detailed panic messages when mocks are missing or duplicated.
Quick Example
type Repository[T any] interface {
FindByID(id string) (T, error)
}
// Generated mock: RepositoryMockImpl[T]
func TestRepositoryMock(t *testing.T) {
repo := NewRepositoryMockImpl[int](gsmock.NewManager())
// Expect panic when no mock is registered
assert.Panic(t, func() {
_, _ = repo.FindByID("1")
}, "no mock code matched")
// Register behavior
repo.MockFindByID().Handle(func(id string) (int, error) {
return 42, nil
})
v, err := repo.FindByID("1")
assert.Nil(t, err)
assert.Equal(t, v, 42)
}
Installation
gs-mock comes with a code generation tool:
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/go-spring/gs/HEAD/install.sh)"
Then in your code:
//go:generate gs mock -o service_mock.go
GitHub
https://github.com/go-spring/gs-mock
I’d love feedback, contributions, and real-world testing reports.
Feel free to open issues or PRs if you find something missing!
Thanks!