Go 🐹

Linting
Formatting
Naming
Imports
Declaration
Slices
Functions
Errors
Testing

Linting

We mainly use the built in command go vet for automated code checks.

Formatting

Use tabs with 8 tab size for indentation.
Format the syntax using go fmt.
Use a single empty line to break between statements to organize logical chunks of code.
End each file with a newline.

Naming

Use UpperCamelCase for public and lowerCamelCase for private interfaces, structs, variables and functions.

// Bad
type hello_world interface{}

type fizz_buzz struct{}

var my_array []string
my_array := []string{}

func foo_bar() {
  // some code
}

// Good
// public
type HelloWorld interface{}

type FizzBuzz struct{}

// private
var myArray []string
myArray := []string{}

func fooBar() {
  // some code
}

Use err as a common variable name for error type.

// Bad
someErr := returnErrorFunc()

// Good
err := returnErrorFunc()

Use lowercase with NO underscore for package names. Prefer conciseness over long names.

// Bad
package string_conversion
package operatingSystem
package documentation
package system_log
package io_utility

// Good
package strconv
package os
package doc
package syslog
package ioutil

Use meaningful variable name for global/local/argument variables and use single letter for loop variables name.

// Bad
var r *redis.Pool
o := getOrders()
u := findUser(i)

for index, customer := range customers {
    ...
}
  
// Good
var RedisPool *redis.Pool
orders := getOrders()
user := findUser(userID)

for i, c := range customers {
    ...
}

Imports

Organize packages in group, separated by blank line between each group.

import (
  // Standard library packages

  // Internal project packages

  // Third-party packages
)

// Bad
import (
  "errors"
  "nimblehq/controllers"
  "net/http"
  "github.com/fizz/buzz"
  "nimblehq/models"
  "github.com/foo/bar"
)

// Good
import (
  "errors"
  "net/http"

  "nimblehq/controllers"
  "nimblehq/models"

  "github.com/fizz/buzz"
  "github.com/foo/bar"
)

Sort packages by alphabetical order for each group.

// Bad
import (
  "net/http"
  "errors"

  "nimblehq/models"
  "nimblehq/controllers"
)

// Good
import (
  "errors"
  "net/http"

  "nimblehq/controllers"
  "nimblehq/models"
)

Use lowercase with NO underscore to rename imported packages. This is often needed to avoid package import conflicts.

// Bad
import (
  "errors"
  goUrl "net/url"

  errors_config "mypackage/config/errors"
  "mypackage/config/url"
)

// Good
import (
  "errors"
  gourl "net/url"

  errorsconf "mypackage/config/errors"
  "mypackage/config/url"
)

Prefer naming module name in go.mod using repository-hosting-domain/user-name/repository-name pattern.
```
// Bad
module my-project
  
// Good
module github.com/nimblehq/my-project
```

Use module name pattern convention when importing an internal module.

// Bad
import (
  "my-project/controllers"
  "my-project/models"

  "github.com/fizz/buzz"
  "github.com/foo/bar"
)

// Good
import (
  "github.com/nimblehq/my-project/controllers"
  "github.com/nimblehq/my-project/models"

  "github.com/fizz/buzz"
  "github.com/foo/bar"
)

Declaration

Prefer grouping all Constants into the block.

// Bad
const failedStatus = "failed"
const pendingStatus = "pending"
const processedStatus = "processed"
  
// Good
const (
  failedStatus = "failed"
  pendingStatus = "pending"
  processedStatus = "processed"
)

Slices

Prefer var s []string over s := []string{} when declaring an empty slice.

Functions

Prefer declaring the type for each parameter over declare single type for all parameters.

// Bad
func fooBar(num1, num2 int, str1, str2 string) {
  // Some code
}

// Good
func fooBar(num1 int, num2 int, str1 string, str2 string) {
  // Some code
}

Prefer unnamed over named return parameters for return values.

// Bad
func fruit(name string) (color, taste string) {
  switch name {
  case "Banana", "Mango":
    color, taste = "Yellow", "Sweet"
  default:
    color, taste = "Unknown", "Unknown"
  }
  return
}

// Good
func fruit(name string) (string, string) {
  var color string
  var taste string

  switch name {
  case "Banana", "Mango":
    color, taste = "Yellow", "Sweet"
  default:
    color, taste = "Unknown", "Unknown"
  }
  return color, taste
}

Prefer early return to avoid deep nesting.

// Bad
func validUser(u *User) bool {
    if u != nil {
        if u.Id != nil {
            return true
        } else {
            return false
        }
    } else {
        return false
    }
}

// Good
func validUser(u *User) bool {
    if u == nil {
        return false
    }
      
    return u.Id != nil
}

Prefer one or two letter abbreviation as the receiver name in the receiver function. The receiver name should be consistent other receiver functions.

// Bad
func (registration *Registration) New() {
    ...
    ...
}
  
func (serverHandler ServerHandler) ServeHTTP(rw ResponseWriter, r *Request) {
    ...
    ...
}
  
// Good
func (r *Registration) New() {
    ...
    ...
}
  
func (sh ServerHandler) ServeHTTP(rw ResponseWriter, r *Request) {
    ...
    ...
}

Errors

DO NOT ignore errors using _ variables if the function returns an error. Check them to make sure the function is completed.

Prefer declare then check over inline error handling for error returning functions.

// Bad
if err := fooBar(); err != nil {
  // Error handling
}

// Good
err := fooBar()
if err != nil {
  // Error handling
}

Prefer reusing the variable err instead of assigning errors to a new variable for error handling since errors must be handled right away.

// Bad
func1Err := returnErrFunc1()
if func1Err != nil {
  // Error handling
}

func2Err := returnErrFunc2()
if func2Err != nil {
  // Error handing
}

// Good
err := returnErrFunc1()
if err != nil {
  // Error handing
}

err = returnErrFunc2()
if err != nil {
  // Error handing
}

DO NOT use panic for handling normal errors. Use error and multiple return values.

Testing

Any test file must have a _test.go suffix as the go test command automatically executes any file with names that match the file pattern *_test.go.
Prefer adding _test suffix to the package name for any test package instead of using the same name as the original package. This naming keeps in sync the file name with the package name.
```
// controllers/foo.go
package controllers

// Bad
// controllers/foo_test.go
package controllers

// Good
// controllers/foo_test.go
package controllers_test
```
Any test function must have a Test prefix as the go test command automatically executes any function that match following pattern.
```
func TestXxx(*testing.T) {
  // Testing code
}
```