Mockc
Mockc is a completely type-safe compile-time mock generator for Go. You can use it just by writing the mock generators with mockc.Implement() or using it with command like flags.
Check out my blog post for more details.
Features
- Tools
- Generating mock with mock generators
- Generating mock with command line flags (experimental feature)
- Generated Mock
- Capturing params and results of the method
- Capturing method calls
- Injecting method body
- Customizing mock's field names with the prefix and the suffix
- default:
prefix:"_",suffix:""
- default:
- Generating mock constructor
Installation
go get github.com/KimMachineGun/mockc/cmd/mockc
Look and Feel
You can see more examples here.
Target Interface
package basic
type Cache interface {
Get(key string) (val interface{}, err error)
Set(key string, val interface{}) (err error)
Del(key string) (err error)
}
If you want to generate mock that implements the above interface, follow the steps below.
With Mock Generator
1. Write Mock Generator
If you want to generate mock with mock generator, write a mock generator first. The mock will be generated in its generator path, and it'll be named its generator's name. You can write multiple generators in one file, and multiple mocks will be generated. The mock generator should be consisted of function calls of the mockc package.
//+build mockc
package basic
import (
"github.com/KimMachineGun/mockc"
)
func MockcCache() {
mockc.Implement(Cache(nil))
}
If you want to customize the field names of the mock, use mockc.SetFieldNamePrefix() or mockc.SetFieldNameSuffix(). (Notice: These functions only work with constant string value.)
2. Generate Mock
This command will generate mock with your mock generator. The <package-pattern> argument will be used for loading mock generator with golang.org/x/tools/go/packages#Load. If it's not provided, . will be used.
mockc [<packages-pattern>]
Ex: mock ./example
With Command Line Flags
1. Generate Mock
This command will generate mock with its command line flags. If you generate mock with this command, you don't need to write the mock generator. The <target-interface-pattern> should follow {package_path}.{interface_name} format.
mockc -destination=<output-file> -name=<mock-name> [-withConstructor] [-fieldNamePrefix=<prefix>] [-fieldNameSuffix=<suffix>] <target-interface-pattern> [<target-interface-pattern>]
Ex: mockc -destination=./example/mockc_gen.go -name=MockcCache github.com/KimMachineGun/mockc/example.Cache
If you want to customize the field names of the mock, pass string value to the -fieldNamePrefix or -fieldNameSuffix.
Generated Mock
The //go:generate directive may vary depending on your mock generation command.
// Code generated by Mockc. DO NOT EDIT.
// repo: https://github.com/KimMachineGun/mockc
//go:generate mockc
// +build !mockc
package basic
import "sync"
var _ interface {
Cache
} = &MockcCache{}
type MockcCache struct {
// method: Del
_Del struct {
mu sync.Mutex
// basics
Called bool
CallCount int
// call history
History []struct {
Params struct {
P0 string
}
Results struct {
R0 error
}
}
// params
Params struct {
P0 string
}
// results
Results struct {
R0 error
}
// if it is not nil, it'll be called in the middle of the method.
Body func(string) error
}
// method: Get
_Get struct {
mu sync.Mutex
// basics
Called bool
CallCount int
// call history
History []struct {
Params struct {
P0 string
}
Results struct {
R0 interface{}
R1 error
}
}
// params
Params struct {
P0 string
}
// results
Results struct {
R0 interface{}
R1 error
}
// if it is not nil, it'll be called in the middle of the method.
Body func(string) (interface{}, error)
}
// method: Set
_Set struct {
mu sync.Mutex
// basics
Called bool
CallCount int
// call history
History []struct {
Params struct {
P0 string
P1 interface{}
}
Results struct {
R0 error
}
}
// params
Params struct {
P0 string
P1 interface{}
}
// results
Results struct {
R0 error
}
// if it is not nil, it'll be called in the middle of the method.
Body func(string, interface{}) error
}
}
func (recv *MockcCache) Del(p0 string) error {
recv._Del.mu.Lock()
defer recv._Del.mu.Unlock()
// basics
recv._Del.Called = true
recv._Del.CallCount++
// params
recv._Del.Params.P0 = p0
// body
if recv._Del.Body != nil {
recv._Del.Results.R0 = recv._Del.Body(p0)
}
// call history
recv._Del.History = append(recv._Del.History, struct {
Params struct {
P0 string
}
Results struct {
R0 error
}
}{
Params: recv._Del.Params,
Results: recv._Del.Results,
})
// results
return recv._Del.Results.R0
}
func (recv *MockcCache) Get(p0 string) (interface{}, error) {
recv._Get.mu.Lock()
defer recv._Get.mu.Unlock()
// basics
recv._Get.Called = true
recv._Get.CallCount++
// params
recv._Get.Params.P0 = p0
// body
if recv._Get.Body != nil {
recv._Get.Results.R0, recv._Get.Results.R1 = recv._Get.Body(p0)
}
// call history
recv._Get.History = append(recv._Get.History, struct {
Params struct {
P0 string
}
Results struct {
R0 interface{}
R1 error
}
}{
Params: recv._Get.Params,
Results: recv._Get.Results,
})
// results
return recv._Get.Results.R0, recv._Get.Results.R1
}
func (recv *MockcCache) Set(p0 string, p1 interface{}) error {
recv._Set.mu.Lock()
defer recv._Set.mu.Unlock()
// basics
recv._Set.Called = true
recv._Set.CallCount++
// params
recv._Set.Params.P0 = p0
recv._Set.Params.P1 = p1
// body
if recv._Set.Body != nil {
recv._Set.Results.R0 = recv._Set.Body(p0, p1)
}
// call history
recv._Set.History = append(recv._Set.History, struct {
Params struct {
P0 string
P1 interface{}
}
Results struct {
R0 error
}
}{
Params: recv._Set.Params,
Results: recv._Set.Results,
})
// results
return recv._Set.Results.R0
}
Feel Free to Use the Generated Mock
package basic
import (
"errors"
"testing"
)
func HasKey(c Cache, key string) (bool, error) {
val, err := c.Get(key)
if err != nil {
return false, err
}
return val != nil, nil
}
func TestHasKey(t *testing.T) {
m := &MockcCache{}
// set return value
m._Get.Results.R0 = struct{}{}
// execute
key := "test_key"
result, err := HasKey(m, key)
// assert
if !result {
t.Error("result should be true")
}
if err != nil {
t.Error("err should be nil")
}
if m._Get.CallCount != 1 {
t.Errorf("Cache.Get should be called once: actual(%d)", m._Get.CallCount)
}
if m._Get.Params.P0 != key {
t.Errorf("Cache.Get should be called with %q: actual(%q)", key, m._Get.Params.P0)
}
}
func TestHasKey_WithBodyInjection(t *testing.T) {
m := &MockcCache{}
// inject body
key := "test_key"
m._Get.Body = func(actualKey string) (interface{}, error) {
if actualKey != key {
t.Errorf("Cache.Get should be called with %q: actual(%q)", key, actualKey)
}
return nil, errors.New("error")
}
// execute
result, err := HasKey(m, key)
// assert
if result {
t.Error("result should be false")
}
if err == nil {
t.Error("err should not be nil")
}
if m._Get.CallCount != 1 {
t.Errorf("Cache.Get should be called once: actual(%d)", m._Get.CallCount)
}
}
