I have a interface, and used mockgen to create mocks:
type Client {
getBytes(ctx context.Context, token, url string) ([]byte, error)
SendRequest(ctx context.Context, token, id string) (Response, error)
}
type Response {
...
}
I used mockgen to create the mock file, which looks good. The generated mock file is as this:
// Code generated by MockGen. DO NOT EDIT.
// Source: utils/myservice/client.go
// Package mock_myservice is a generated GoMock package.
package mock_myservice
import (
context "context"
reflect "reflect"
gomock "github.com/golang/mock/gomock"
myservice "github.com/robinhoodmarkets/rh/inbox/utils/myservice"
)
// MockClient is a mock of Client interface.
type MockClient struct {
ctrl *gomock.Controller
recorder *MockClientMockRecorder
}
// MockClientMockRecorder is the mock recorder for MockClient.
type MockClientMockRecorder struct {
mock *MockClient
}
// NewMockClient creates a new mock instance.
func NewMockClient(ctrl *gomock.Controller) *MockClient {
mock := &MockClient{ctrl: ctrl}
mock.recorder = &MockClientMockRecorder{mock}
return mock
}
// EXPECT returns an object that allows the caller to indicate expected use.
func (m *MockClient) EXPECT() *MockClientMockRecorder {
return m.recorder
}
// SendRequest mocks base method.
func (m *MockClient) SendRequest(ctx context.Context, token, id string) (myservice.ToggleSettingsItemResponse, error) {
m.ctrl.T.Helper()
ret := m.ctrl.Call(m, "SendRequest", ctx, token, id)
ret0, _ := ret[0].(myservice.ToggleSettingsItemResponse)
ret1, _ := ret[1].(error)
return ret0, ret1
}
// SendRequest indicates an expected call of SendRequest.
func (mr *MockClientMockRecorder) SendRequest(ctx, token, id interface{}) *gomock.Call {
mr.mock.ctrl.T.Helper()
return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "SendRequest", reflect.TypeOf((*MockClient)(nil).SendRequest), ctx, token, id)
}
// getBytes mocks base method.
func (m *MockClient) **getBytes**(ctx context.Context, token, url string) ([]byte, error) {
m.ctrl.T.Helper()
ret := m.ctrl.Call(m, "getBytes", ctx, token, url)
ret0, _ := ret[0].([]byte)
ret1, _ := ret[1].(error)
return ret0, ret1
}
// getBytes indicates an expected call of getBytes.
func (mr *MockClientMockRecorder) getBytes(ctx, token, url interface{}) *gomock.Call {
mr.mock.ctrl.T.Helper()
return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "getBytes", reflect.TypeOf((*MockClient)(nil).getBytes), ctx, token, url)
}
However, when I tried to used in unittests, i goet this error:
*MockClient does not implement Client (missing getBytes method):
have: mock_myservice.getBytes(context.Context, string, string) ([]byte, error)
want: myservice.getBytes(context.Context, string, string) ([]byte, error)
This is wired since the function is indeed in the mocked file.
Actually I figured out myself:
getBytes is not a public function, as the function names doesn't start with capitalized letter, and hence the implementation is unable to be matched.
This is likely a mockgen issue, as it should give some warning for such usage.
Related
This is the code I am testing
func listObjects(cli *client.Client, options clientOptions) ([]BlobObjects, error) {
objects, err := cli.ListBlobObjects(...)
}
In my test setup I do this
type MockClient struct {
MockListBlobObjects func() ([]BlobObjects, error)
}
func (m *MockClient) ListBlobObjects(....) ([]BlobObjects, error) {
// return some mock response
}
And this is my test case
func TestBlobObjects(t *testing.T) {
tests := map[string]struct {
client *MockClient
...
}{
"Test case 1": {
client: &MockClient{
MockListBlobObjects: ....,
},
....
},
....
for testName, test := range tests {
blobs, err := (test.client, clientOptions{})
// make assertions here
}
The problem is test.client. Compiler is telling me
cannot use test.client (variable of type *MockClient) as *client.Client value in argument to listObjects
My hope was I have a mock client and if I call the function under test, then the mock client passed will call the mocked listObjects. This is how I would do in Python.
What should I do in Golang?
You need to create a common interface, which will be implemented by both types
type Client interface {
ListBlobObjects func() ([]BlobObjects, error)
}
type RealClient struct {
}
func (c *RealClient) ListBlobObjects(....) ([]BlobObjects, error) {
// return some response
}
type MockClient struct {
// note: don't put method signature in function body
}
func (m *MockClient) ListBlobObjects(....) ([]BlobObjects, error) {
// return some mock response
}
and then
var client client.Client
client = &RealClient{}
// or
client = &MockClient{}
I've mocked a repository interface and I want to return a specific value when a method is called. However, it always returns what's in the dummy implementation.
type MockUserRepo struct {
mock.Mock
}
// dummy method to fulfil the interface
func (m *MockUserRepo) FindByUsername(username string) (*User, error) {
return nil, nil
}
Now, I setup the mock as such
m := NewMockUserRepo()
m.On("FindByUsername", mock.Anything).Return(&User{
Username: "test"
}, nil)
// inject mock
svc := NewService(m)
user, err := svc.FindByUsername("anything") // always nil,nil
The return value (user, err) is always nil (or whatever is returned in MockUserRepo.FindByUsername
Is there something I'm doing wrong?
source : https://pkg.go.dev/github.com/stretchr/testify/mock#hdr-Example_Usage
For objects of your own type, use the generic Arguments.Get(index) method and make a type assertion: return args.Get(0).(*MyObject), args.Get(1).(*AnotherObjectOfMine)
So in your FindByUsername method change to this:
func (m *MockUserRepo) FindByUsername(username string) (*User, error) {
args := m.Called(username)
return args.Get(0).(*User), args.Error(1)
}
playground
I have a simple Gin server with one of the routes called /metadata.
What the handler does is it reads a file from the system, say /etc/myapp/metadata.json and returns the JSON in the response.
But when the file is not found, handler is configured to return following error.
500: metadata.json does not exists or not readable
On my system, which has the metadata.json file, the test passes. Here is the test function I am using:
package handlers_test
import (
"net/http"
"net/http/httptest"
"testing"
"myapp/routes"
"github.com/stretchr/testify/assert"
)
func TestMetadataRoute(t *testing.T) {
router := routes.SetupRouter()
w := httptest.NewRecorder()
req, _ := http.NewRequest("GET", "/metadata", nil)
router.ServeHTTP(w, req)
assert.NotNil(t, w.Body)
assert.Equal(t, 200, w.Code)
assert.Contains(t, w.Body.String(), "field1")
assert.Contains(t, w.Body.String(), "field2")
assert.Contains(t, w.Body.String(), "field3")
assert.Contains(t, w.Body.String(), "field4")
}
But on CI environment, the test would fail because it won't find metadata.json. And would return the configured error.
What can be done?
I have this handler:
func GetMetadata(c *gin.Context) {
// read the info
content, err := ioutil.ReadFile("/etc/myapp/metadata.json")
if err != nil {
c.JSON(http.StatusInternalServerError,
gin.H{"error": "metadata.json does not exists or not readable"})
return
}
// deserialize to json
var metadata models.Metadata
err = json.Unmarshal(content, &metadata)
if err != nil {
c.JSON(http.StatusInternalServerError,
gin.H{"error": "unable to parse metadata.json"})
return
}
c.JSON(http.StatusOK, metadata)
}
What Volker is suggesting is to use a package-level unexported variable. You give it a fixed default value, corresponding to the path you need in production, and then simply overwrite that variable in your unit test.
handler code:
var metadataFilePath = "/etc/myapp/metadata.json"
func GetMetadata(c *gin.Context) {
// read the info
content, err := ioutil.ReadFile(metadataFilePath)
// ... rest of code
}
test code:
func TestMetadataRoute(t *testing.T) {
metadataFilePath = "testdata/metadata_test.json"
// ... rest of code
}
This is a super-simple solution. There are ways to improve on this, but all are variations of how to inject any variable in a Gin handler. For simple request-scoped configuration, what I usually do is to inject the variable into the Gin context. This requires slightly refactoring some of your code:
router setup code with middleware for production
func SetupRouter() {
r := gin.New()
r.GET("/metadata", MetadataPathMiddleware("/etc/myapp/metadata.json"), GetMetadata)
// ... rest of code
}
func MetadataPathMiddleware(path string) gin.HandlerFunc {
return func(c *gin.Context) {
c.Set("_mdpath", path)
}
}
handler code extracting the path from context:
func GetMetadata(c *gin.Context) {
metadataFilePath := c.GetString("_mdpath")
content, err := ioutil.ReadFile(metadataFilePath)
// ... rest of code
}
test code which you should refactor to test the handler only (more details: How to unit test a Go Gin handler function?):
func TestMetadataRoute(t *testing.T) {
// create Gin test context
w := httptest.NewRecorder()
c, _ := gin.CreateTestContext(w)
// inject test value into context
c.Set("_mdpath", "testdata/metadata_test.json")
// just test handler, the passed context holds the test value
GetMetadata(c)
// ... assert
}
Note: setting context values with string keys is somewhat discouraged, however the Gin context accepts only string keys.
I need to create a Pull Request comment using go-github, and my code works, but now I'd like to write tests for it (yes, I'm aware that tests should come first), so that I don't actually call the real GitHub service during test.
I've read 3 blogs on golang stubbing and mocking, but, being new to golang, I'm a bit lost, despite this discussion on go-github issues. For example, I wrote the following function:
// this is my function
func GetClient(token string, url string) (*github.Client, context.Context, error) {
ctx := context.Background()
ts := oauth2.StaticTokenSource(
&oauth2.Token{AccessToken: token},
)
tc := oauth2.NewClient(ctx, ts)
client, err := github.NewEnterpriseClient(url, url, tc)
if err != nil {
fmt.Printf("error creating github client: %q", err)
return nil, nil, err
}
return client, ctx, nil
}
How could I stub that?
Similarly, I have this:
func GetPRComments(ctx context.Context, client *github.Client) ([]*github.IssueComment, *github.Response, error) {
opts := &github.IssueListCommentsOptions{
ListOptions: github.ListOptions{
Page: 1,
PerPage: 30,
},
}
githubPrNumber, err := strconv.Atoi(os.Getenv("GITHUB_PR_NUMBER"))
if err != nil || githubPrNumber == 0 {
panic("error: GITHUB_PR_NUMBER is not numeric or empty")
}
// use Issues API for PR comments since GitHub docs say "This may seem counterintuitive... but a...Pull Request is just an Issue with code"
comments, response, err := client.Issues.ListComments(
ctx,
os.Getenv("GITHUB_OWNER"),
os.Getenv("GITHUB_REPO"),
githubPrNumber,
opts)
if err != nil {
return nil, nil, err
}
return comments, response, nil
}
How should I stub that?
My thought was to perhaps use dependency injection by creating my own structs first, but I'm not sure how, so currently I have this:
func TestGetClient(t *testing.T) {
client, ctx, err := GetClient(os.Getenv("GITHUB_TOKEN"), "https://example.com/api/v3/")
c, r, err := GetPRComments(ctx, client)
...
}
I would start with an interface:
type ClientProvider interface {
GetClient(token string, url string) (*github.Client, context.Context, error)
}
When testing a unit that needs to call GetClient make sure you depend on your ClientProvider interface:
func YourFunctionThatNeedsAClient(clientProvider ClientProvider) error {
// build you token and url
// get a github client
client, ctx, err := clientProvider.GetClient(token, url)
// do stuff with the client
return nil
}
Now in your test, you can construct a stub like this:
// A mock/stub client provider, set the client func in your test to mock the behavior
type MockClientProvider struct {
GetClientFunc func(string, string) (*github.Client, context.Context, error)
}
// This will establish for the compiler that MockClientProvider can be used as the interface you created
func (provider *MockClientProvider) GetClient(token string, url string) (*github.Client, context.Context, error) {
return provider.GetClientFunc(token, url)
}
// Your unit test
func TestYourFunctionThatNeedsAClient(t *testing.T) {
mockGetClientFunc := func(token string, url string) (*github.Client, context.Context, error) {
// do your setup here
return nil, nil, nil // return something better than this
}
mockClientProvider := &MockClientProvider{GetClientFunc: mockGetClientFunc}
// Run your test
err := YourFunctionThatNeedsAClient(mockClientProvider)
// Assert your result
}
These ideas aren't my own, I borrowed them from those who came before me; Mat Ryer suggested this (and other ideas) in a great video about "idiomatic golang".
If you want to stub the github client itself, a similar approach can be used, if github.Client is a struct, you can shadow it with an interface. If it is already an interface, the above approach works directly.
I'm writing a REST API using Gin framework. But I was faced a trouble testing my controllers and researching TDD and Mock. I tried to apply TDD and Mock to my code but I could not.
I created a very reduced test environment and tried to create a controller test. How do I create a Mock for Gin.Context?
Here's my example code:
package main
import (
"strconv"
"github.com/gin-gonic/gin"
)
// MODELS
type Users []User
type User struct {
Name string `json"name"`
}
func main() {
r := gin.Default()
r.GET("/users", GetUsers)
r.GET("/users/:id", GetUser)
r.Run(":8080")
}
// ROUTES
func GetUsers(c *gin.Context) {
repo := UserRepository{}
ctrl := UserController{}
ctrl.GetAll(c, repo)
}
func GetUser(c *gin.Context) {
repo := UserRepository{}
ctrl := UserController{}
ctrl.Get(c, repo)
}
// CONTROLLER
type UserController struct{}
func (ctrl UserController) GetAll(c *gin.Context, repository UserRepositoryIterface) {
c.JSON(200, repository.GetAll())
}
func (ctrl UserController) Get(c *gin.Context, repository UserRepositoryIterface) {
id := c.Param("id")
idConv, _ := strconv.Atoi(id)
c.JSON(200, repository.Get(idConv))
}
// REPOSITORY
type UserRepository struct{}
type UserRepositoryIterface interface {
GetAll() Users
Get(id int) User
}
func (r UserRepository) GetAll() Users {
users := Users{
{Name : "Wilson"},
{Name : "Panda"},
}
return users
}
func (r UserRepository) Get(id int) User {
users := Users{
{Name : "Wilson"},
{Name : "Panda"},
}
return users[id-1]
}
My test example:
package main
import(
"testing"
_ "github.com/gin-gonic/gin"
)
type UserRepositoryMock struct{}
func (r UserRepositoryMock) GetAll() Users {
users := Users{
{Name : "Wilson"},
{Name : "Panda"},
}
return users
}
func (r UserRepositoryMock) Get(id int) User {
users := Users{
{Name : "Wilson"},
{Name : "Panda"},
}
return users[id-1]
}
// TESTING REPOSITORY FUNCTIONS
func TestRepoGetAll(t *testing.T) {
userRepo := UserRepository{}
amountUsers := len(userRepo.GetAll())
if amountUsers != 2 {
t.Errorf("Esperado %d, recebido %d", 2, amountUsers)
}
}
func TestRepoGet(t *testing.T) {
expectedUser := struct{
Name string
}{
"Wilson",
}
userRepo := UserRepository{}
user := userRepo.Get(1)
if user.Name != expectedUser.Name {
t.Errorf("Esperado %s, recebido %s", expectedUser.Name, user.Name)
}
}
/* HOW TO TEST CONTROLLER?
func TestControllerGetAll(t *testing.T) {
gin.SetMode(gin.TestMode)
c := &gin.Context{}
c.Status(200)
repo := UserRepositoryMock{}
ctrl := UserController{}
ctrl.GetAll(c, repo)
}
*/
Gin provides the option to create a Test Context which you can use for whatever you need:
https://godoc.org/github.com/gin-gonic/gin#CreateTestContext
Like that:
c, _ := gin.CreateTestContext(httptest.NewRecorder())
Here is an example of how I mock a context, add a param, use it in a function, then print the string of the response if there was a non-200 response.
gin.SetMode(gin.TestMode)
w := httptest.NewRecorder()
c, _ := gin.CreateTestContext(w)
c.Params = []gin.Param{gin.Param{Key: "k", Value: "v"}}
foo(c)
if w.Code != 200 {
b, _ := ioutil.ReadAll(w.Body)
t.Error(w.Code, string(b))
}
In order to get a *gin.Context instance that you can test, you need a mock HTTP request and response. An easy way to create those is to use the net/http and net/http/httptest packages. Based on the code you linked, your test would look like this:
package main
import (
"net/http"
"net/http/httptest"
"testing"
"github.com/gin-gonic/gin"
)
func TestControllerGetAll(t *testing.T) {
// Switch to test mode so you don't get such noisy output
gin.SetMode(gin.TestMode)
// Setup your router, just like you did in your main function, and
// register your routes
r := gin.Default()
r.GET("/users", GetUsers)
// Create the mock request you'd like to test. Make sure the second argument
// here is the same as one of the routes you defined in the router setup
// block!
req, err := http.NewRequest(http.MethodGet, "/users", nil)
if err != nil {
t.Fatalf("Couldn't create request: %v\n", err)
}
// Create a response recorder so you can inspect the response
w := httptest.NewRecorder()
// Perform the request
r.ServeHTTP(w, req)
// Check to see if the response was what you expected
if w.Code != http.StatusOK {
t.Fatalf("Expected to get status %d but instead got %d\n", http.StatusOK, w.Code)
}
}
Although you could create a mock *gin.Context, it's probably easier to use the method above, since it'll execute and handle your request the same as it would an actual request.
If to reduce the question to "How to create mock for a function argument?" the answer is: use interfaces not concrete types.
type Context struct is a concrete type literal and Gin doesn't provide appropriate interface. But you can declare it by yourself. Since you are using only JSON method from Context you can declare extra-simple interface:
type JSONer interface {
JSON(code int, obj interface{})
}
And use JSONer type instead Context type in all your functions which expect Context as argument:
/* Note, you can't declare argument as a pointer to interface type,
but when you call it you can pass pointer to type which
implements the interface.*/
func GetUsers(c JSONer) {
repo := UserRepository{}
ctrl := UserController{}
ctrl.GetAll(c, repo)
}
func GetUser(c JSONer) {
repo := UserRepository{}
ctrl := UserController{}
ctrl.Get(c, repo)
}
func (ctrl UserController) GetAll(c JSONer, repository UserRepositoryIterface) {
c.JSON(200, repository.GetAll())
}
func (ctrl UserController) Get(c JSONer, repository UserRepositoryIterface) {
id := c.Param("id")
idConv, _ := strconv.Atoi(id)
c.JSON(200, repository.Get(idConv))
}
And now it is easy to test
type ContextMock struct {
JSONCalled bool
}
func (c *ContextMock) JSON(code int, obj interface{}){
c.JSONCalled = true
}
func TestControllerGetAll(t *testing.T) {
gin.SetMode(gin.TestMode)
c := &ContextMock{false}
c.Status(200)
repo := UserRepositoryMock{}
ctrl := UserController{}
ctrl.GetAll(c, repo)
if c.JSONCalled == false {
t.Fail()
}
}
Example simple as possible.
There is another question with a close sense