Go 🐹

Linting
Formatting
Naming
Imports
Declaration
Slices
Functions
Errors
Testing

The Go language comes with its own sets of recommendations. Nimble general code conventions apply when they do not go against these recommendations.

Linting

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

Formatting

Use a tab of 4 spaces for indentation.
Format the syntax using go fmt.
Use a single blank line to break between statements and 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{}

type HtmlEvent struct{}

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

func foo_bar() {
    // some code
}

func PublishApi() {
    // some code
}

// Good
// public
type HelloWorld interface{}

type FizzBuzz struct{}

type HTMLEvent struct{}

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

func fooBar() {
    // some code
}

func publishAPI() {
    // 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 names for global/local/argument variables and single-letter names for loop variables.

// 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 groups, separated by a 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 modules in go.mod using the repository-hosting-domain/user-name/repository-name pattern.
```
// Bad
module my-project

// Good
module github.com/nimblehq/my-project
```

Use this module name pattern convention when importing internal modules.

// 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 a single 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 declaring a 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 return parameters.

// 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 returns 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 letters abbreviation as the function receiver name. Such names should be consistent with the 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) {
    ...
    ...
}

Prefer placing all private functions after the public functions.

// Bad
func myPrivateFunction() {}

func MyPublicFunction() {}

// Good
func MyPublicFunction() {}

func myPrivateFunction() {}

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 — 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 the _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. The go test command automatically executes any function that matches this pattern.
```
func TestXxx(*testing.T) {
    // Testing code
}
```

Prefer describing method name with the # prefix and function name with the . prefix in unit tests. This convention is only applicable when using the Ginkgo testing framework.

// Go method
func (u *User) Save() error {...}

// Go function
func IsBlank(value string) bool {...}

// Bad
Describe("Save", func() { ... })
Describe(".Save", func() { ... })

Describe("IsBlank", func() { ... })
Describe("#IsBlank", func() { ... })

// Good
Describe("#Save", func() { ... })

Describe(".IsBlank", func() { ... })