Testing Patterns Skill
Comprehensive Go testing patterns following community best practices.
When to Use
Use this skill when writing or reviewing tests.
Table-Driven Tests
go
func TestAdd(t *testing.T) {
tests := []struct {
name string
a, b int
want int
}{
{"positive", 1, 2, 3},
{"negative", -1, -2, -3},
{"zero", 0, 0, 0},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got := Add(tt.a, tt.b)
if got != tt.want {
t.Errorf("Add(%d, %d) = %d; want %d", tt.a, tt.b, got, tt.want)
}
})
}
}
Using Testify
go
import (
"testing"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
func TestService_GetUser(t *testing.T) {
svc := NewService()
user, err := svc.GetUser(1)
require.NoError(t, err)
assert.Equal(t, "John", user.Name)
assert.Greater(t, user.ID, 0)
}
Mocking with Interfaces
go
type UserRepository interface {
GetUser(id int) (*User, error)
}
type mockUserRepo struct {
users map[int]*User
}
func (m *mockUserRepo) GetUser(id int) (*User, error) {
if user, ok := m.users[id]; ok {
return user, nil
}
return nil, ErrNotFound
}
func TestService(t *testing.T) {
repo := &mockUserRepo{
users: map[int]*User{
1: {ID: 1, Name: "John"},
},
}
svc := NewService(repo)
// test with mock
}
HTTP Testing
go
func TestHandler(t *testing.T) {
req := httptest.NewRequest("GET", "/users/1", nil)
w := httptest.NewRecorder()
handler := NewHandler(mockService)
handler.GetUser(w, req)
assert.Equal(t, http.StatusOK, w.Code)
assert.Contains(t, w.Body.String(), "John")
}
Best Practices
- •Use table-driven tests
- •Test one thing per test
- •Use testify for clarity
- •Mock external dependencies
- •Test edge cases
- •Run with race detector:
go test -race