Make debugging a breeze with Dependency Injection in GoLang

Dependency injection is the idea of removing dependencies from within a function and aids in building a more resilient codebase by doing so.

Removing dependencies from a function also makes it easier to debug because tests are more straightforward to conduct.

To better understand dependency injection, an example will be shown using test-driven development.

Example

Suppose we have a file called user.json containing a single user's information, and we want to get their age via a function.

Data Structure

// user.json { "age": 34 } 

Function

type User struct { Age int `json:"age"` } // GetUserData opens a file and returns a piece of data func GetUserData(fPath String) (String, error) { userFile, err := os.Open(fPath) if err != nil { fmt.Println(err) } byteValue, _ := ioutil.ReadAll(userFile) var u User json.Unmarshal(byteValue, &u) return u } 

Test Function

func TestGetUserData(t *testing.T) { t.Parallel() got, _ := GetUserData("../test/resources/user.json") s := fmt.Sprint(got) if s == "" { t.Errorf("Wanted %s got %s", got, s) } } 

Dependencies

The above function works, and the test also works. However, the following dependencies have been introduced:

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